Long-term effects of low glycemic index/load vs. high glycemic index/load diets on parameters of obesity and obesity-associated risks: a systematic review and meta-analysis

Glycemic Index and Appetite Response of Iron-Biofortified Cowpeas (Vigna unguiculata (l.) Walp.) in Healthy Adults and Its Effects on Inflammation and Oxidative Stress in Raw 264.7 Cells

OBJECTIVE

This study aimed to determine the glycemic index of conventional and biofortified cowpeas, their effects on healthy individuals' appetite, and their anti-inflammatory and antioxidant effects in RAW 264.7 cells.

METHODS

Iron biofortified (BRS Aracê, BRS Tumucumaque, and BRS Xiquexique) and conventional (BRS Pajeú) cowpeas were cooked and their chemical composition was analyzed. Eutrophic adults (n = 11) consumed each cowpea and control glucose and post-prandial glucose and appetite responses were obtained over 120 min. In vitro, the study used RAW 264.7 cells stimulated with lipopolysaccharide-LPS (1 µML) and treated with digested cowpea beans (1 mg/mL). Total antioxidant capacity (TAC), nitric oxide, superoxide dismutase (SOD), TNF-α, and IL-10 were analyzed in the cell and culture medium, and NF-κB by immunohistochemistry. The data were analyzed by ANOVA and post-hoc of Tukey (p < 0.05).

RESULTS

All cowpeas had a lower incremental area under the glycemic curve (iAUC) than glucose. In appetite responses, Pajeú had the lowest "hunger sensation" and higher "satiety sensation" (p < 0.05). In vitro analysis showed that Pajeú and Tumucumaque improved TAC and biofortified cowpeas reduced the activation and translocation of NF-κB to nuclei. However, the cowpeas had no effects on SOD activity, nitric oxide, TNF-α, and IL-10 released and production into cells (p > 0.05).

CONCLUSIONS

Cowpea, biofortified or not, presents benefits in reducing the glycemic index, but has a moderate impact on induced inflammation, being a sustainable option for human intake and health.

CLINICAL TRIAL REGISTRATION

Brazilian Clinical Trials Registry (ReBEC), number RBR-7ntftdv.

Dietary Relationships between Obesity and Inflammatory Bowel Diseases: A Narrative Review of Diets Which May Promote Both Diseases

PURPOSE OF REVIEW

The pandemic of obesity preceded global spread of Inflammatory Bowel diseases by almost 2 decades. A pathogenic relationship has been described between obesity and inflammatory bowel diseases, but Crohn`s disease may be selectively impacted. The role of diet in pathogenesis has also gained significant support in the last few decades. This review explores dietary relationships to account for epidemiological observations. Quantifiable indices for diets have been described including a glycemic index, inflammatory indices and levels of food processing. Meta-analyses have been published which examine each for effects on obesity and co-morbidities as well as Crohn's disease and ulcerative colitis. This review suggests that ultra-processed foods provide the best link between obesity and Crohn's disease explaining epidemiological observations. However, the other 2 types of dietary indices likely contribute to ulcerative colitis as well as to co-morbidities related to both obesity and inflammatory bowel diseases. The term ultra-processed foods cover a large number of additives and extensive work is needed to define individual or combined harmful effects. Furthermore, the interactions among the 3 main indices need clarification in order to precisely apply therapeutic diets to both diseases (obesity and inflammatory bowel disease).

The effect of low-carbohydrate diets, based on changes in intake of dietary saturated fats on circulating TNF-α and interleukin- 6 levels in adults: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Low-carbohydrate diets (LCDs) have been associated with inflammation while there is still conflicting evidence regarding the effects of this type of diet on inflammatory markers and the clinical benefit of them remains uncertain. So, we aimed to ascertain the effects of LCDs on serum concentrations of tumor necrosis factor alpha (TNF-α) and interleukin- 6 (IL- 6) by performing a systematic review and meta-analysis of randomized clinical trials (RCTs).

METHODS

The online databases PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, Web of Science, and Scopus were comprehensively searched up to February 2024, to find pertinent RCTs. Pooled weighted mean difference (WMD) with 95% confidence intervals (CIs) were calculated using the random-effects model.

RESULTS

This meta-analysis of 33 studies assessed a total of 2106 adults irrespective of their health status. Compared with control group, participants on LCDs experienced a decline in IL- 6 levels (WMD: - 0.31 pg/mL; 95% CI: - 0.49 to - 0.12; P = 0.001). However, no significant effect was revealed for TNF-α (WMD: - 0.02 pg/mL; 95% CI: - 0.08 to - 0.03; P = 0.449). Stratification analyses indicated that beneficial effects of LCDs on inflammatory cytokines (WMD: - 0.28 pg/mL; 95% CI: - 0.47 to - 0.10; P = 0.003, WMD: - 0.26 pg/mL; 95% CI: - 0.48 to - 0.03; P = 0.027, for TNF-α and IL- 6, respectively) were stronger when carbohydrate intake was < 10%. The results of Meta-regression analyses suggested that baseline level of both markers remained as a strong predictor of the effect size (P = 0.038 and P = 0.001 for TNF-α and IL- 6, respectively).

CONCLUSION

Adherence to LCDs appeared to be effective at improving inflammatory cytokines particularly, when carbohydrate intake was restricted to less than 10% of total energy. Nevertheless, further rigorously designed clinical trials considering factors such as race and genetic, the sources and quality of dietary carbohydrates, protein, and fat are required to gain a deeper understanding of the impact of LCDs on inflammatory markers.

TRIAL REGISTRATION

PROSPERO, registration no: CRD42023387452.

Impact of Dietary Fiber on Inflammation in Humans

Cohort studies consistently show that a high intake of cereal fiber and whole-grain products is associated with a decreased risk of type 2 diabetes (T2DM), cancer, and cardiovascular diseases. Similar findings are also reported for infectious and chronic inflammatory disorders. All these disorders are at least partially caused by inflammaging, a chronic state of inflammation associated with aging and Metabolic Syndrome. Surprisingly, insoluble (cereal) fiber intake consistently shows stronger protective associations with most long-term health outcomes than soluble fiber. Most humans consume soluble fiber mainly from sweet fruits, which usually come with high levels of sugar, counteracting the potentially beneficial effects of fiber. In both observational and interventional studies, high-fiber diets show a beneficial impact on inflammation, which can be attributed to a variety of nutrients apart from dietary fiber. These confounders need to be considered when evaluating the effects of fiber as part of complex dietary patterns. When assessing specific types of fiber, inulin and resistant starch clearly elicit anti-inflammatory short-term effects, while results for pectins, beta-glucans, or psyllium turn out to be less convincing. For insoluble fiber, promising but sparse data have been published so far. Hypotheses on putative mechanisms of anti-inflammatory fiber effects include a direct impact on immune cells (e.g., for pectin), fermentation to pleiotropic short-chain fatty acids (for fermentable fiber only), modulation of the gut microbiome towards higher levels of diversity, changes in bile acid metabolism, a differential release of gut hormones (such as the glucose-dependent insulinotropic peptide (GIP)), and an improvement of insulin resistance via the mTOR/S6K1 signaling cascade. Moreover, the contribution of phytate-mediated antioxidative and immune-modulatory means of action needs to be considered. In this review, we summarize the present knowledge on the impact of fiber-rich diets and dietary fiber on the human inflammatory system. However, given the huge heterogeneity of study designs, cohorts, interventions, and outcomes, definite conclusions on which fiber to recommend to whom cannot yet be drawn.

Fruit Carbohydrates and Their Impact on the Glycemic Index: A Study of Key Determinants

Background: Fruits are a convenient and natural source of carbohydrates that can rapidly affect blood sugar levels and the glycemic index (GI). The GI plays a crucial role in the management of chronic diseases, including diabetes, obesity, hyperglycemia, and diet-related illnesses. Despite there being several health benefits linked with consuming fruits, it remains unclear which specific components of fruits are the key determinants that significantly influence the GI. Methods: This study retrospectively examined the relationship between different types of carbohydrates and the GI of various fruits to determine their correlation. The fruits' sugar and fiber contents were identified from available public databases, the U.S. Department of Agriculture (USDA), FooDB, PubMed, and published sources. Results: Previously, the GI was determined by the available carbohydrates, which include different types of sugar. In this study, individual hexose sugars, along with the total carbohydrates and dietary fiber, were examined. The results indicated a strong correlation between fructose and the GI, whereas glucose and total glucose did not exhibit such a correlation. The total carbohydrate-to-fiber ratio displayed a stronger correlation (R = 0.57 and p > 0.0001) with the GI compared to glucose alone (R = 0.37; p = 0.01) or the total glucose (R = 0.45; p = 0.0009) with the consideration of fiber, while the scattering of data points around the regression line suggested that factors beyond the total carbohydrate and fiber also contribute to determining the GI. Conclusions: This study demonstrated that individual hexose sugars, especially fructose, significantly influence the GI. These findings suggest that the carbohydrate-to-fiber ratio may offer a more accurate and reliable metric for determining the GI than traditional methods. Further research is warranted to investigate the specific contribution of dietary fiber components, fruit texture, micronutrients, vitamins, genetic predispositions, gut microbiota, and the body's physiological status to gain a deeper understanding of GI regulation.

The impact of a low-carbohydrate (vs. low-fat) diet on fat mass loss in African American women is modulated by insulin sensitivity

OBJECTIVE

The objective of this study was to examine the independent and interactive effects of insulin sensitivity (SI), the acute insulin response to glucose, and diet on changes in fat mass (FM), resting and total energy expenditure (REE and TEE, respectively), and mechanical efficiency, during weight loss, in African American women with obesity.

METHODS

A total of 69 women were randomized to low-fat (55% carbohydrate [CHO], 20% fat) or low-CHO (20% CHO, 55% fat) hypocaloric diets for 10 weeks, followed by a 4-week weight-stabilization period (controlled feeding). SI and acute insulin response to glucose were measured at baseline with an intravenous glucose tolerance test; body composition was measured with bioimpedance analysis at baseline and week 10; and REE, TEE, and mechanical efficiency were measured with indirect calorimetry, doubly labeled water, and a submaximal bike test, respectively, at baseline and week 14.

RESULTS

Within the group with low SI, those on the low-CHO diet lost more weight (mean [SE], -6.6 [1.0] vs. -4.1 [1.4] kg; p = 0.076) and FM (-4.9 [0.9] vs. -2.1 [1.0] kg; p = 0.04) and experienced a lower reduction in REE (-48 [30] vs. -145 [30] kcal/day; p = 0.035) and TEE (mean [SE] 67 [56] vs. -230 [125] kcal/day; p = 0.009) compared with those on the low-fat diet.

CONCLUSIONS

A low-CHO diet leads to a greater FM loss in African American women with obesity and low SI, likely by minimizing the reduction in EE that follows weight loss.

Nutritional and Phytochemical Profiling of Vicia faba L. var. Minor Seeds: a Multifaceted Exploration of Natural Antioxidants and Functional Food Potential

This study explores the nutritional and phytochemical profiling of twenty-three genotypes of Vicia faba L. var. minor seeds cultivated in the experimental field of the Arid Lands Institute of Medenine. Our comprehensive analysis encompasses fatty acid composition, sugar content, phytochemical composition, and antioxidant potential, providing a nuanced understanding of the seeds' nutritive quality. The investigation revealed substantial variations among genotypes, showcasing the potential for targeted nutritional enhancement. Quantification of total polyphenols, flavonoids, condensed tannins, and radical scavenging activities revealed average values of 16.46 mg GAE/g DW, 6.27 mg CTE/g DW, 0.47 mg CE/g DW, and 0.146 mM TEAC, respectively. Notably, the seeds exhibited a low tannin content, a desirable trait for animal feed applications. Liquid chromatography-mass spectrometry (LC-MS) was employed for the identification of phenolic compounds, unearthing the prevalence of quinic acid and flavanols, including catechin (+) and epicatechin. Sugar analysis identified the presence of glucose and sucrose, emphasizing the seeds' unique carbohydrate composition. Gas chromatography elucidated the fatty acid profile, spotlighting prominent components such as palmitic acid (13.87%), stearic acid (3.37%), oleic acid (27.66%), linoleic acid (45.83%), and linolenic acid (3.53%). The findings underscore the seeds' nutritive significance, positioning them as rich sources of natural antioxidants, fatty acids, and phenolic compounds. Moreover, the extracts' favorable tannin content positions them as potential candidates for functional food applications, showcasing their promise as sources of bioactive molecules with diverse applications.

Effects of a culturally tailored low-glycaemic index dietary educational intervention on reducing cardiometabolic risk among Chinese adults with obesity: a randomized controlled trial

AIMS

An assessor-blinded randomized controlled trial was conducted to assess the effect of a culturally tailored low-glycaemic index (GI) dietary educational intervention on body mass index and cardiometabolic risks for Chinese people with obesity in Hong Kong.

METHODS AND RESULTS

A total of 166 Chinese adults in Hong Kong with obesity were randomized to the intervention group (n = 83) or the control group (n = 83). The intervention group received the culturally sensitive low-GI dietary educational intervention based on the health belief model, consisting of an educational booklet, one individual interactive educational session, and three follow-up telephone calls. The control group received general advice on a healthy diet, including a pamphlet, one individual education session, and three follow-up telephone calls. Outcome measures included body mass index, cardiometabolic risk factors, dietary intake variables, and sense of satiety. Data collection was conducted at baseline and post-intervention at 12 weeks. A generalized estimating equation model was used to compare the difference in changes in outcome variables between groups. Compared with the control group, the intervention group exhibited a significant reduction in dietary glycaemic load (β = -6.963, P = 0.026) at post-intervention. No significant effects were found on other outcomes.

CONCLUSION

A 12-week culturally tailored and health belief model-based low-GI dietary educational intervention significantly reduced the dietary glycaemic load and showed the feasibility of the low-GI dietary intervention in Chinese adults in Hong Kong with obesity. A longer intervention period and follow-up might be required to achieve improvements in reducing cardiometabolic risk factors in people with obesity.

REGISTRATION

ClinicalTrials.gov: NCT04152213.

Weight loss associated with low-energy diets with different glycaemic loads does not improve arterial stiffness: a randomised clinical trial

We evaluated the effects of two low-energy diets with different glycaemic loads on arterial stiffness in adults with excess weight. This was a 45-day parallel-group, randomised clinical trial including seventy-five participants (20-59 years; BMI 32 kg/m2). They were assigned to two similar low-energy diets (reduction of ∼750 kcal.d-1) with macronutrient composition (55 % carbohydrates, 20 % proteins and 25 % lipids) but different glycaemic loads: high-glycaemic load (HGL 171 g.d-1; n 36) or low-glycaemic load (LGL 67 g.d-1; n 39). We evaluated: arterial stiffness (pulse wave velocity, PWV); augmentation index (AIx@75); reflection coefficient; fasting blood glucose; fasting lipid profile; blood pressure and body composition. We found no improvements in PWV (P = 0·690) and AIx@75 (P = 0·083) in both diet groups, but there was a decrease in the reflection coefficient in the LGL group (P = 0·003) compared with baseline. The LGL diet group showed reductions in body weight (Δ -4·9 kg; P = 0·001), BMI (Δ -1·6 kg/m2; P = 0·001), waist circumference (Δ -3·1 cm; P = 0·001), body fat (Δ -1·8 %; P = 0·034), as well as TAG (Δ -14·7 mg/dl; P = 0·016) and VLDL (Δ -2·8 mg/dl; P = 0·020). The HGL diet group showed a reduction in total cholesterol (Δ -14·6 mg/dl; P = 0·001), LDL (Δ -9·3 mg/dl; P = 0·029) but a reduction in HDL (Δ -3·7 mg/dl; P = 0·002). In conclusion, a 45-day intervention with low-energy HGL or LGL diets in adults with excess weight was not effective to improve arterial stiffness. However, the LGL diet intervention was associated with a reduction of reflection coefficient and improvements in body composition, TAG and VLDL levels.

Low-Carbohydrate Diet Macronutrient Quality and Weight Change

Importance

The associations of low-carbohydrate diets (LCDs) with long-term weight management remains unclear, and the source and quality of macronutrients within LCDs are less explored.

Objectives

To prospectively examine associations between changes in LCD indices and weight change among US adults.

Design, Setting, and Participants

This prospective cohort study included initially healthy participants at baseline from the Nurses' Health Study (NHS; 1986-2010), Nurses' Health Study II (NHSII; 1991-2015), and Health Professionals Follow-up Study (HPFS; 1986-2018). Data analysis was performed between November 2022 and April 2023.

Exposures

Five LCD indices were examined: (1) a total LCD (TLCD) emphasizing overall lower carbohydrate intake; (2) an animal-based LCD (ALCD) that emphasized animal-sourced protein and fat; (3) a vegetable-based LCD (VLCD) that emphasized plant-sourced protein and fat; (4) a healthy LCD (HLCD) emphasizing less refined carbohydrates, more plant protein, and healthy fat; and (5) an unhealthy LCD (ULCD) emphasizing less healthful carbohydrates, more animal protein, and unhealthy fat.

Main Outcomes and Measures

The outcome of interest was 4-year changes in self-reported body weight.

Results

A total of 123 332 participants (mean [SD] age, 45.0 [9.7] years; 103 320 [83.8%] female) were included in this study. The median carbohydrate intake (as a percentage of energy) of the highest quintiles of TLCD score at baseline ranged from 38.3% in HPFS to 40.9% in NHSII. Mean weight gain over 4-year intervals among participants varied from 0.8 kg in the HPFS to 1.8 kg in the NHSII. After adjusting for demographics and baseline and concomitant changes of selected lifestyle factors, each 1-SD increase in TLCD score was associated with 0.06 (95% CI, 0.04-0.08) kg more weight gain over the 4-year periods. Similarly, participants gained 0.13 (95% CI, 0.11 to 0.14) kg per each 1-SD increase in ALCD score and 0.39 (95% CI, 0.37 to 0.40) kg per each 1-SD change in ULCD score. In contrast, each 1-SD increase in VLCD score was associated with 0.03 (95% CI, 0.01 to 0.04) kg less weight gain, and each 1-SD increase in HLCD score was associated with 0.36 (95% CI, 0.35 to 0.38) kg less weight gain. The associations were more pronounced among obese individuals (per 1-SD increase in HLCD score: BMI ≥30, 0.88 [95% CI, 0.80, 0.97] kg less weight gain; BMI <25, 0.23 [95% CI, 0.20, 0.26] kg less weight gain; P for interaction < .001).

Conclusions and Relevance

These findings suggest that the quality of LCDs may play a critical role in modulating long-term weight change. Only LCDs that emphasized high-quality protein, fat, and carbohydrates from whole grains and other plant-based foods were associated with less weight gain.

Evaluation of the effect of obesity, dietary glycemic index and metabolic profiles on the cardiovascular risk in children with classical phenylketonuria

OBJECTIVES

To compare the glycemic index(GI),obesity,echocardiographic,and arterial stiffness measurements with the healthy control group to evaluate the cardiovascular risk of pediatric classical phenylketonuria(PKU).

METHODS

The study was a prospective observational,involving 104 pediatric volunteers between 2019 and 2020.Two groups were formed:the PKU patient group and the healthy control group.These two groups were further divided into three subgroups:obese,overweight,and normal weight.The patients' anthropometric measurements,body fat analysis,biochemical analysis, GI and glycemic load(GL),arterial stiffness measurements,and echocardiographic findings were recorded.

RESULTS

The PKU patient group's glucose,total cholesterol,LDL,and HDL values were significantly lower than the healthy control group(p = 0.010 for glucose and p = 0.001 for total cholesterol,LDL and HDL).Triglyceride levels were higher in the PKU patient group than in the healthy controls(109.6 vs. 76.7 mg/dl,p = 0.001). GI and GL were significantly lower in the PKU patient group than in the healthy control group(GI 453 vs. 392.9,p = 0.017 and GL 101.1 vs. 85.5,p = 0.036).Left ventricular mass(LVM)-z-score and LVM index were significantly higher in the PKU group than in the healthy control group(LVM z-score 0.9 vs. 0.5,p = 0.014 and LVM index 38.9 vs. 32.7 g/m2.7,p = 0.001). A moderately statistically significant positive correlation was found between the mean phenylalanine(phe) value and pulse wave velocity(PWV) among the PKU patient groups(R: 0.477,p < 0.001).A moderately statistically significant positive correlation was also found between waist circumference and PWV in the PKU patient group(R:0.541, p < 0.001).

CONCLUSIONS

Our study found that close follow-up of phe levels and PWV is more critical than obesity, GI, and GL in the cardiovascular evaluation of classical PKU patients.A large number of multicenter pediatric studies are needed in this area.

Low Greenhouse Gas Emission Self-Selective Diets and Risk of Metabolic Syndrome in Adults 40 and Older: A Prospective Cohort Study in South Korea

BACKGROUND

The food system accounts for ∼ 40 % of human-generated greenhouse gas (GHG) emissions. Meanwhile, daily diet selection also impacts human nutrition status and health.

OBJECTIVES

This study aimed to use the alternate Mediterranean Diet (aMED) score to evaluate the quality of a low-GHG emission diet and the association with risk of developing metabolic syndrome (MetS).

METHODS

A total of 41,659 healthy participants without MetS 40 y of age or older were selected from the Health Examinees Study, an ongoing cohort study in South Korea from 2004. A dietary GHG emissions database was compiled following a national project and literature review. MetS was defined according to the Adult Treatment Panel III criteria of the National Cholesterol Education Program. The participants were grouped into quintiles based on 2,000  kcal -standardized daily diet-GHG emissions (Q1: the lowest energy-adjusted diet-GHG emissions). A multivariable logistic regression model was used to analyze the risk for MetS at follow-up. The aMED score was used to assess the diet quality of the different diet-related GHG emission groups.

RESULTS

Females with lower energy-adjusted diet-related GHG emissions had significantly lower risks of developing MetS (p = 0.0043 ) than those with the highest energy-adjusted diet-related GHG emissions. In addition, the Q1 group, in comparison with the other groups, had a higher aMED score (3.02 for males and 3.00 for females), which indicated that the participants in this group had a diet that more closely matched the Mediterranean diet.

DISCUSSION

These findings provide a reference for dietary guidance and other policies aimed toward improving dietary intake and reducing diet-related GHG emissions in South Korea and worldwide. https://doi.org/10.1289/EHP12727.

Analysis of the association between dietary patterns and nonalcoholic fatty liver disease in a county in Guangxi

BACKGROUND

This study aims to investigate the relationship between different dietary patterns and non-alcoholic fatty liver disease (NAFLD).

METHODS

Residents over 30 years old in the ecological longevity cohort in Gongcheng Yao Autonomous County, Guangxi Province were the research objects selected from 2018 to 2019. Physical examination, baseline population survey, and food frequency questionnaire (FFQ) survey were conducted. Dietary patterns were analyzed by factor analysis. Influencing factors of NAFLD were analyzed by multiple logistic regression.

RESULTS

NAFLD was diagnosed in 241 of 2664 participants based on ultrasonography, and the detection rate was 9.0%. Factor analysis yielded a total of three dietary patterns, namely, traditional Chinese, Western, and cereal-potato dietary patterns. Results of multivariate logistic regression analysis showed that after adjusting for confounding factors, participants in the highest quartile of the Western dietary pattern exhibited a higher prevalence of NAFLD (OR = 2.799; 95% CI: 1.620-4.837; p < 0.05) than participants in the lowest quartile. Participants in the highest quartile of the cereal-potato pattern exhibited a decreased risk of NAFLD compared with those in the lowest quartile (OR = 0.581; 95% CI: 0.371-0.910, p < 0.05). The traditional Chinese patterns did not show any association with the risk of NAFLD.

CONCLUSIONS

The Western dietary pattern increases the risk of NAFLD, whereas the cereal-potato dietary pattern reduces the risk of NAFLD. It is important for the prevention and control of NAFLD to adhere to the cereal-potato dietary.

Effect of Dietary Approaches on Glycemic Control in Patients with Type 2 Diabetes: A Systematic Review with Network Meta-Analysis of Randomized Trials

BACKGROUND

Dietary patterns play a critical role in diabetes management, while the best dietary pattern for Type 2 diabetes (T2DM) patients is still unclear. The aim of this network meta-analysis was to compare the impacts of various dietary approaches on the glycemic control of T2DM patients.

METHODS

Relevant studies were retrieved from PubMed, Embase, Web of Knowledge, Cochrane Central Register of Controlled Trials (CENTRAL), and other additional records (1949 to 31 July 2022). Eligible RCTs were those comparing different dietary approaches against each other or a control diet in individuals with T2DM for at least 6 months. We assessed the risk of bias of included studies with the Cochrane risk of bias tool and confidence of estimates with the Grading of Recommendations Assessment, Development, and Evaluation approach for network meta-analyses. In order to determine the pooled effect of each dietary approach relative to each other, we performed a network meta-analysis (NMA) for interventions for both HbA1c and fasting glucose, which enabled us to estimate the relative intervention effects by combing both direct and indirect trial evidence.

RESULTS

Forty-two RCTs comprising 4809 patients with T2DM were included in the NMA, comparing 10 dietary approaches (low-carbohydrate, moderate-carbohydrate, ketogenic, low-fat, high-protein, Mediterranean, Vegetarian/Vegan, low glycemic index, recommended, and control diets). In total, 83.3% of the studies were at a lower risk of bias or had some concerns. Findings of the NMA revealed that the ketogenic, low-carbohydrate, and low-fat diets were significantly effective in reducing HbA1c (viz., -0.73 (-1.19, -0.28), -0.69 (-1.32, -0.06), and -1.82 (-2.93, -0.71)), while moderate-carbohydrate, low glycemic index, Mediterranean, high-protein, and low-fat diets were significantly effective in reducing fasting glucose (viz., -1.30 (-1.92, -0.67), -1.26 (-2.26, -0.27), -0.95 (-1.51, -0.38), -0.89 (-1.60, -0.18) and -0.75 (-1.24, -0.27)) compared to a control diet. The clustered ranking plot for combined outcomes indicated the ketogenic, Mediterranean, moderate-carbohydrate, and low glycemic index diets had promising effects for controlling HbA1c and fasting glucose. The univariate meta-regressions showed that the mean reductions of HbA1c and fasting glucose were only significantly related to the mean weight change of the subjects.

CONCLUSIONS

For glycemic control in T2DM patients, the ketogenic diet, Mediterranean diet, moderate-carbohydrate diet, and low glycemic index diet were effective options. Although this study found the ketogenic diet superior, further high-quality and long-term studies are needed to strengthen its credibility.

Interactions Between Genetic Risk Score and Healthy Plant Diet Index on Cardiometabolic Risk Factors Among Obese and Overweight Women

People with higher genetic predisposition to obesity are more susceptible to cardiovascular diseases (CVDs) and healthy plant-based foods may be associated with reduced risks of obesity and other metabolic markers. We investigated whether healthy plant-foods-rich dietary patterns might have inverse associations with cardiometabolic risk factors in participants at genetically elevated risk of obesity. For this cross-sectional study, 377 obese and overweight women were chosen from health centers in Tehran, Iran. We calculated a healthy plant-based diet index (h-PDI) in which healthy plant foods received positive scores, and unhealthy plant and animal foods received reversed scores. A genetic risk score (GRS) was developed based on 3 polymorphisms. The interaction between GRS and h-PDI on cardiometabolic traits was analyzed using a generalized linear model (GLM). We found significant interactions between GRS and h-PDI on body mass index (BMI) (p = 0.02), body fat mass (p = 0.04), and waist circumference (p = 0.056). There were significant gene-diet interactions for healthful plant-derived diets and BMI-GRS on high-sensitivity C-reactive protein (p = 0.03), aspartate aminotransferase (p = 0.04), alanine transaminase (p = 0.05), insulin (p = 0.04), and plasminogen activator inhibitor 1 (p = 0.002). Adherence to h-PDI was more strongly related to decreased levels of the aforementioned markers among participants in the second or top tertile of GRS than those with low GRS. These results highlight that following a plant-based dietary pattern considering genetics appears to be a protective factor against the risks of cardiometabolic abnormalities.

Low glycaemic index or low glycaemic load diets for people with overweight or obesity

BACKGROUND

The prevalence of obesity is increasing worldwide, yet nutritional management remains contentious. It has been suggested that low glycaemic index (GI) or low glycaemic load (GL) diets may stimulate greater weight loss than higher GI/GL diets or other weight reduction diets. The previous version of this review, published in 2007, found mainly short-term intervention studies. Since then, randomised controlled trials (RCTs) with longer-term follow-up have become available, warranting an update of this review.

OBJECTIVES

To assess the effects of low glycaemic index or low glycaemic load diets on weight loss in people with overweight or obesity.

SEARCH METHODS

We searched CENTRAL, MEDLINE, one other database, and two clinical trials registers from their inception to 25 May 2022. We did not apply any language restrictions.

SELECTION CRITERIA

We included RCTs with a minimum duration of eight weeks comparing low GI/GL diets to higher GI/GL diets or any other diets in people with overweight or obesity.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. We conducted two main comparisons: low GI/GL diets versus higher GI/GL diets and low GI/GL diets versus any other diet. Our main outcomes included change in body weight and body mass index, adverse events, health-related quality of life, and mortality. We used GRADE to assess the certainty of the evidence for each outcome.

MAIN RESULTS

In this updated review, we included 10 studies (1210 participants); nine were newly-identified studies. We included only one study from the previous version of this review, following a revision of inclusion criteria. We listed five studies as 'awaiting classification' and one study as 'ongoing'. Of the 10 included studies, seven compared low GI/GL diets (233 participants) with higher GI/GL diets (222 participants) and three studies compared low GI/GL diets (379 participants) with any other diet (376 participants). One study included children (50 participants); one study included adults aged over 65 years (24 participants); the remaining studies included adults (1136 participants). The duration of the interventions varied from eight weeks to 18 months. All trials had an unclear or high risk of bias across several domains.  Low GI/GL diets versus higher GI/GL diets Low GI/GL diets probably result in little to no difference in change in body weight compared to higher GI/GL diets (mean difference (MD) -0.82 kg, 95% confidence interval (CI) -1.92 to 0.28; I2 = 52%; 7 studies, 403 participants; moderate-certainty evidence). Evidence from four studies reporting change in body mass index (BMI) indicated low GI/GL diets may result in little to no difference in change in BMI compared to higher GI/GL diets (MD -0.45 kg/m2, 95% CI -1.02 to 0.12; I2 = 22%; 186 participants; low-certainty evidence)at the end of the study periods. One study assessing participants' mood indicated that low GI/GL diets may improve mood compared to higher GI/GL diets, but the evidence is very uncertain (MD -3.5, 95% CI -9.33 to 2.33; 42 participants; very low-certainty evidence). Two studies assessing adverse events did not report any adverse events; we judged this outcome to have very low-certainty evidence. No studies reported on all-cause mortality.    For the secondary outcomes, low GI/GL diets may result in little to no difference in fat mass compared to higher GI/GL diets (MD -0.86 kg, 95% CI -1.52 to -0.20; I2 = 6%; 6 studies, 295 participants; low certainty-evidence). Similarly, low GI/GL diets may result in little to no difference in fasting blood glucose level compared to higher GI/GL diets (MD 0.12 mmol/L, 95% CI 0.03 to 0.21; I2 = 0%; 6 studies, 344 participants; low-certainty evidence).  Low GI/GL diets versus any other diet Low GI/GL diets probably result in little to no difference in change in body weight compared to other diets (MD -1.24 kg, 95% CI -2.82 to 0.34; I2 = 70%; 3 studies, 723 participants; moderate-certainty evidence). The evidence suggests that low GI/GL diets probably result in little to no difference in change in BMI compared to other diets (MD -0.30 kg in favour of low GI/GL diets, 95% CI -0.59 to -0.01; I2 = 0%; 2 studies, 650 participants; moderate-certainty evidence). Two adverse events were reported in one study: one was not related to the intervention, and the other, an eating disorder, may have been related to the intervention. Another study reported 11 adverse events, including hypoglycaemia following an oral glucose tolerance test. The same study reported seven serious adverse events, including kidney stones and diverticulitis. We judged this outcome to have low-certainty evidence. No studies reported on health-related quality of life or all-cause mortality. For the secondary outcomes, none of the studies reported on fat mass. Low GI/GL diets probably do not reduce fasting blood glucose level compared to other diets (MD 0.03 mmol/L, 95% CI -0.05 to 0.12; I2 = 0%; 3 studies, 732 participants; moderate-certainty evidence).  AUTHORS' CONCLUSIONS: The current evidence indicates there may be little to no difference for all main outcomes between low GI/GL diets versus higher GI/GL diets or any other diet. There is insufficient information to draw firm conclusions about the effect of low GI/GL diets on people with overweight or obesity. Most studies had a small sample size, with only a few participants in each comparison group. We rated the certainty of the evidence as moderate to very low. More well-designed and adequately-powered studies are needed. They should follow a standardised intervention protocol, adopt objective outcome measurement since blinding may be difficult to achieve, and make efforts to minimise loss to follow-up. Furthermore, studies in people from a wide range of ethnicities and with a wide range of dietary habits, as well as studies in low- and middle-income countries, are needed.

Position statement on nutrition therapy for overweight and obesity: nutrition department of the Brazilian association for the study of obesity and metabolic syndrome (ABESO-2022)

Obesity is a chronic disease resulting from multifactorial causes mainly related to lifestyle (sedentary lifestyle, inadequate eating habits) and to other conditions such as genetic, hereditary, psychological, cultural, and ethnic factors. The weight loss process is slow and complex, and involves lifestyle changes with an emphasis on nutritional therapy, physical activity practice, psychological interventions, and pharmacological or surgical treatment. Because the management of obesity is a long-term process, it is essential that the nutritional treatment contributes to the maintenance of the individual's global health. The main diet-related causes associated with excess weight are the high consumption of ultraprocessed foods, which are high in fats, sugars, and have high energy density; increased portion sizes; and low intake of fruits, vegetables, and grains. In addition, some situations negatively interfere with the weight loss process, such as fad diets that involve the belief in superfoods, the use of teas and phytotherapics, or even the avoidance of certain food groups, as has currently been the case for foods that are sources of carbohydrates. Individuals with obesity are often exposed to fad diets and, on a recurring basis, adhere to proposals with promises of quick solutions, which are not supported by the scientific literature. The adoption of a dietary pattern combining foods such as grains, lean meats, low-fat dairy, fruits, and vegetables, associated with an energy deficit, is the nutritional treatment recommended by the main international guidelines. Moreover, an emphasis on behavioral aspects including motivational interviewing and the encouragement for the individual to develop skills will contribute to achieve and maintain a healthy weight. Therefore, this Position Statement was prepared based on the analysis of the main randomized controlled studies and meta-analyses that tested different nutrition interventions for weight loss. Topics in the frontier of knowledge such as gut microbiota, inflammation, and nutritional genomics, as well as the processes involved in weight regain, were included in this document. This Position Statement was prepared by the Nutrition Department of the Brazilian Association for the Study of Obesity and Metabolic Syndrome (ABESO), with the collaboration of dietitians from research and clinical fields with an emphasis on strategies for weight loss.

The Physiological Regulation of Body Fat Mass

Disturbances inbody weight and adiposity in both humans and animals are met by compensatory adjustments in energy intake and energy expenditure, suggesting that body weight or fat is regulated. From a clinical viewpoint, this is likely to contribute to the difficulty that many people with obesity have in maintaining weight loss. Finding ways to modify these physiologic responses is likely to improve the long-term success of obesity treatments.

Longitudinal Associations of Dietary Sugars and Glycaemic Index with Indices of Glucose Metabolism and Body Fatness during 3-Year Weight Loss Maintenance: A PREVIEW Sub-Study

BACKGROUND

Dietary sugars are often linked to the development of overweight and type 2 diabetes (T2D) but inconsistencies remain.

OBJECTIVE

We investigated associations of added, free, and total sugars, and glycaemic index (GI) with indices of glucose metabolism (IGM) and indices of body fatness (IBF) during a 3-year weight loss maintenance intervention.

DESIGN

The PREVIEW (PREVention of diabetes through lifestyle Intervention and population studies in Europe and around the World) study was a randomised controlled trial designed to test the effects of four diet and physical activity interventions, after an 8-week weight-loss period, on the incidence of T2D. This secondary observational analysis included pooled data assessed at baseline (8), 26, 52, 104 and 156 weeks from 514 participants with overweight/obesity (age 25-70 year; BMI ≥ 25 kg⋅m^-2) and with/without prediabetes in centres that provided data on added sugars (Sydney and Helsinki) or free sugars (Nottingham). Linear mixed models with repeated measures were applied for IBF (total body fat, BMI, waist circumference) and for IGM (fasting insulin, HbA1c, fasting glucose, C-peptide). Model A was adjusted for age and intervention centre and Model B additionally adjusted for energy, protein, fibre, and saturated fat.

RESULTS

Total sugars were inversely associated with fasting insulin and C-peptide in all centres, and free sugars were inversely associated with fasting glucose and HbA1c (Model B: all p < 0.05). Positive associations were observed between GI and IGM (Model B: fasting insulin, HbA1c, and C-peptide: (all p < 0.01), but not for added sugars. Added sugar was positively associated with body fat percentage and BMI, and GI was associated with waist circumference (Model B: all p < 0.01), while free sugars showed no associations (Model B: p > 0.05).

CONCLUSIONS

Our findings suggest that added sugars and GI were independently associated with 3-y weight regain, but only GI was associated with 3-y changes in glucose metabolism in individuals at high risk of T2D.

Investigating family history of diabetes as a predictor of fasting insulin and fasting glucose activity in a sample of healthy weight adults

AIMS

Type 2 diabetes is a major public health problem for the global community. Having a family history of diabetes significantly increases risk for diabetes development and understanding how family history contributes to diabetes risk could lead to more effective prevention efforts for at-risk individuals. In a previous study, we showed family history of diabetes is a significant predictor of fasting insulin in healthy weight children. The present study aimed to use the National Health and Nutrition Examination Survey (NHANES 2017) to apply similar multiple regression models to a population of healthy weight adults to determine if family history is a significant predictor of fasting glucose and fasting insulin.

METHODS

Fasting glucose (mg/dL) and fasting insulin (pmol/L) were used as dependent variables in each model, respectively, with family history of diabetes as the independent variable. Covariates for each model included age, gender, race/ethnicity, waist circumference, and macronutrient intake.

RESULTS

The model significantly predicted the variance of fasting glucose [(F(11,364) = 34.80, p < 0.001, R² = 0.2342] and fasting insulin [F(11,343) = 17.58, p < 0.001, R² = 0.1162]. After adjusting for covariates, family history was a significant predicator of fasting glucose (p = 0.0193) as well as age, gender, non-Hispanic black ethnicity, waist circumference, and fat intake. Significant predictors of fasting insulin included gender and waist circumference, but not family history (p = 0.8264). In addition, fasting glucose was higher in individuals with a family history of diabetes (p = 0.033).

CONCLUSIONS

These results add to the understanding of how family history influences the biomarkers that contribute to diabetes development. Knowledge of how family history of diabetes relates to fasting insulin and fasting glucose activity in healthy weight individuals can be used to design personalized screening and early prevention strategies.

One-year nutrition counselling in the context of a Mediterranean diet reduced the dietary inflammatory index in women with breast cancer: a role for the dietary glycemic index

Background: the Mediterranean diet, the low dietary glycemic index (GI) and the dietary inflammation index (DII®) have been associated with lower risk of breast cancer (BC) incidence and mortality. Objective: to investigate whether one-year nutrition counselling in the context of a Mediterranean diet, with or without low-GI carbohydrates counselling, may influence the DII in women with BC. Methods: data were obtained from participants of DEDiCa trial randomized to a Mediterranean diet (MD, n = 112) or a Mediterranean diet with low-GI carbohydrates (MDLGI, n = 111). The diet-derived DII and GI were calculated from 7-day food records while Mediterranean diet adherence from PREDIMED questionnaire. Differences between study arms were evaluated through Fisher's exact test or Mann-Whitney test and associations with multivariable regression analyses. Results: Mediterranean diet adherence significantly increased by 15% in MD and 20% in MDLGI with no difference between arms (p < 0.326). Dietary GI significantly decreased from 55.5 to 52.4 in MD and 55.1 to 47.6 in MDLGI with significant difference between arms (p < 0.001). DII significantly decreased by 28% in MD and 49% in MDLGI with no difference between arms (p < 0.360). Adjusting for energy intake (E-DII) did not change the results. Higher Mediterranean diet adherence and lower dietary GI independently contributed to DII lowering (β-coefficient -0.203, p < 0.001; 0.046, p = 0.003, respectively). Conclusions: DII and E-DII scores decreased significantly after one-year with 4 nutrition counselling sessions on the Mediterranean diet and low GI. Increased adherence to the Mediterranean diet and low GI independently contributed to the DII changes. These results are relevant given that lowering the inflammatory potential of the diet may have implications in cancer prognosis and overall survival.

Effects of anti-inflammatory dietary patterns on non-alcoholic fatty liver disease: a systematic literature review

PURPOSE

Non-alcoholic fatty liver disease (NAFLD) is the leading chronic hepatic condition. Low-grade chronic inflammation contributes to disease progression. Diet has protective effects on hepatic health and inflammatory pathways. The purpose of this review is to systematically review and describe the effects of anti-inflammatory dietary patterns on NAFLD.

METHODS

The Cochrane CENTRAL Library, Cumulative Index of Nursing and Allied Health Literature, Embase, MEDLINE and Web of Science databases were searched. A total of 252 records were identified, 7 of which were included in this review. The revised Cochrane risk-of-bias tool was used to conduct a quality assessment for randomised trials. Certainty of evidence was assessed using the grading of recommendations, assessment, development, and evaluation tool.

RESULTS

Of the 7 included studies, 6 were classified as low risk of bias and studies ranged from high to very low certainty of evidence. In the randomised-controlled studies systematically reviewed, either adherence to the Mediterranean, DASH, or FLiO diet was studied, against usual care or energy matched controls, with a total of 255 participants. Anti-inflammatory dietary pattern adherence significantly reduced the severity of most hepatic and inflammatory markers, and secondary outcomes. A minority of outcomes were improved significantly more than controls.

CONCLUSION

Anti-inflammatory dietary patterns showed benefits to NAFLD risk factors, severity markers and inflammatory markers compared to the control diet. It is unclear whether reductions in the evaluated parameters are related solely to the anti-inflammatory diet or weight loss resulting from caloric restriction, as improvements in control groups were also evidenced. Current limited body of evidence indicates need for further research including isocaloric dietary patterns, longer interventions, measures of inflammatory markers, and studies including normal-weight subjects to confirm findings at higher certainty.

PROSPERO REGISTRATION

CRD42021269382.

Does the concept of "ultra-processed foods" help inform dietary guidelines, beyond conventional classification systems? NO

The Nova classification of ultra-processed foods (UPFs) rests on poorly defined food processes and the presence of food additives from a chemically heterogeneous group, easily leading to misclassification. UPFs are claimed to promote overconsumption of energy and obesity due to high palatability, but little evidence supports effects beyond those that can be accounted for by nutrient composition, energy density, and food matrices. Observational studies link dietary intake of UPFs with obesity, but none have demonstrated independent associations after controlling for likely confounders. A highly cited randomized controlled feeding study that compared a UPF diet with an unprocessed diet showed a rapidly weaning effect on energy intake that can be entirely explained by more conventional and quantifiable dietary factors, including energy density, intrinsic fiber, glycemic load, and added sugar. Clearly, many aspects of food processing can affect health outcomes, but conflating them into the notion of ultra-processing is unnecessary, because the main determinants of chronic disease risk are already captured by existing nutrient profiling systems. In conclusion, the Nova classification adds little to existing nutrient profiling systems; characterizes several healthy, nutrient-dense foods as unhealthy; and is counterproductive to solve the major global food production challenges.

Low glycaemic index and glycaemic load diets in adults with excess weight: Systematic review and meta-analysis of randomised clinical trials

BACKGROUND

To compare the effects of low and high glycaemic index/glycaemic load (GI/GL) diets on body weight in adults with excess weight.

METHODS

We searched for randomised controlled trials comparing low GI/GL vs. high GI/GL diets from Medline (via PubMed), Embase, Scopus and Web of Science. The variables of interest were anthropometric measurements, fasting glucose and fasting insulin levels and lipid profile, and 10 studies were included in the meta-analysis.

RESULTS

The sample size ranged from 19 to 203 participants. Low GI/GL is not superior to high GI/GL diets on body weight reduction in adults with excess weight (body mass index [BMI] ≥ 25 kg m^-2 ). However, low GI/GL diets show greater body weight reductions in adults with BMI ≥ 30 kg m^-2 (-0.93 kg; 95% confidence interval [CI] = -1.73 to -0.12; p = 0.045). Compared with high GI/GL diets, low GI/GL diets may also help reduce fasting glucose (-1.97 mg dl^-1 ; 95% CI = -3.76 to 0.19; p = 0.030) and fasting insulin (-0.55 µU ml^-1 ; 95% CI = -0.95 to -0.15; p = 0.007). No differences in fat mass, fat-free mass, waist circumference and lipid profile were observed between low GI/GL and high GI/GL diets. The risk of bias for body weight was classified as 'low risk' (25% of the studies) and 'some concerns' for all domains of RoB 2 tool in most studies.

CONCLUSIONS

When compared with high GI/GL diets, low GI/GL diets appear to more effectively reduce fasting glucose and insulin and promote greater body weight reduction in adults with obesity (BMI ≥ 30 kg m^-2 ).

The Role of Dietary Glycemic Index and Glycemic Load in Mediating Genetic Susceptibility via MC4R s17782313 Genotypes to Affect Cardiometabolic Risk Factors among Apparently Healthy Obese Individuals

Background

The association of genetic and dietary factors with occurrence and progression of chronic diseases such as metabolic syndrome (MetS) has long been addressed but there is a lack of evidence for complex interrelationships, including direct and indirect effects of these variables. Hence, this study is aimed at evaluating the mediating role of glycemic indices in the association of melanocortin-4 receptor (MC4R) rs17782313 polymorphism, sociodemographic, and psychological factors with the risk of MetS in obese adults using structural equation modeling.

Methods

We performed a cross-sectional analysis of data from 287 apparently healthy adults. Dietary glycemic index (GI) and glycemic load (GL) were calculated from a validated 147-item food frequency questionnaire (FFQ). MC4R s17782313 genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Structural equation modeling was used to explore direct and indirect effects of genetic and nongenetic factors on MetS.

Results

MC4R gene variant was directly associated with the risk of MetS (B = 0.010; P = 0.023). On the other hand, this variant was found to be indirectly and positively associated with LDL-C (B = 6.589; P = 0.042) through mediatory effects of GI and GL. Moreover, GI and GL also mediated indirect positive effects of sex and age on LDL-C (B = 3.970; P ≤ 0.01; B = 0.878; P ≤ 0.01, respectively) and HDL (B = 2.203; P ≤ 0.01; B = 0.129; P ≤ 0.01, respectively). MC4R rs17782313 polymorphism had positive effects on GI (B = 1.577; P ≤ 0.01) and GL (B = 1.235; P ≤ 0.01).

Conclusion

Our data may state a hypothesis of the mediating effect of quantity and quality of carbohydrates consumed in relationship between genetic susceptibility to obesity and cardiometabolic risk factors. Further analyses should be carried out in high-quality cohort studies in order to confirm the findings.

Comparison of nutritional composition between plant-based drinks and cow's milk

The high decline in liquid milk consumption in Western countries has been compensated by the increased consumption of processed dairy products and the rapidly increasing number of new plant-based beverages constantly introduced in the market, advertised as milk substitutes and placed on shelves near milk products. To provide better understanding about the nutritional value of these drinks compared with cow's milk, 27 plant-based drinks of 8 different species and two milk samples were purchased from two big retailers in Switzerland, and their composition regarding protein, carbohydrate, fat, vitamin, and mineral contents and residue load [glyphosate, aminomethylphosphonic acid (AMPA), and arsenic] was analyzed quantitatively and qualitatively. Energy and nutrient intakes were calculated and compared with the dietary reference values for Germany, Austria and Switzerland (D-A-CH). In addition, the digestible indispensable amino acid score (DIAAS) was calculated to estimate the quality of the proteins. Milk contained more energy; fat; carbohydrate; vitamins C, B2, B12, and A; biotin; pantothenic acid; calcium; phosphorus; and iodine than most plant-based drinks. Soy drinks provided slightly more protein and markedly more vitamins B1 and B6, folic acid, and vitamins E and D2 (with supplemented vitamin D2) and K1, magnesium, manganese, iron, and copper than milk and the other plant-based drinks. However, with the exception of cow's milk and soy drinks, which had > 3% protein, most milk alternatives contained ≤ 1% protein; therefore, they cannot be considered good protein sources. In regard to protein quality, milk was outstanding compared with all plant-based drinks and exhibited higher calculated DIAASs. Our results show that the analyzed plant-based drinks are not real alternatives to milk in terms of nutrient composition, even if the actual fortification is taken into account. Improved fortification is still an issue and can be optimized using the most bioavailable and soluble derivatives. Complete replacement of milk with plant-based drinks without adjusting the overall diet can lead to deficiencies of certain important nutrients in the long term.

The association between dietary glycemic index and cardio-metabolic risk factors in obese individuals

Background:

The dietary glycemic index (GI) has been introduced as a novel index to elucidate the potential of foods to increase postprandial glucose. According to the limited available data about the association of GI with cardio-metabolic risk factors such as lipid profile, blood glucose markers, and blood pressure in developing countries, the current study was conducted to investigate this association in apparently obese individuals.

Method and material:

Three hundred forty-seven obese adults were recruited in the present cross-sectional study. A validated 147-food item semi-quantitative food frequency questionnaire (FFQ) was used to evaluate the usual dietary intake of study participants. Dietary GI was calculated using the international GI database. Fatty acid desaturase (FADs)2 gene variants were determined according to polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). ANOVA was used to compare study variables across different tertile of GI.

Results:

We found significant differences in terms of anthropometric parameters [weight (P = 0.038), waist circumference (WC) (P = 0.023), weight to hip ratio (WHR) (P = 0.007), and fat-free mass (FFM) (P < 0.001)] between different tertiles of GI. Similarly, energy and macronutrient intakes had a significant difference across dietary GI, and subjects with a higher dietary intake of energy and macronutrients (carbohydrate, protein, and total fat) were assigned to the third tertile of dietary GI (P < 0.001). While there was no significant difference in terms of cardio-metabolic risk factors in different dietary GI tertiles. Moreover, the total GI score was non-significantly higher in the TT genotype of FADS2 gene polymorphism compared with other genotypes. While no significant difference was observed between FADS2 genotype frequencies in different GI tertiles.

Conclusion:

Calculated dietary GI was associated with several cardio-metabolic risk factors in obese individuals. However, further prospective studies and clinical trials are needed to confirm our findings.

Nutrition and the state of the intestinal microflora in the formation of the metabolic syndrome

The literature review presents the results of modern studies of the relationship between diet and intestinal microbiota in the regulation of metabolic disorders. Metabolic syndrome, which is a symptom complex that combines abdominal obesity, insulin resistance, hyperglycemia, dyslipidemia and arterial hypertension, remains an important problem, being a risk factor for cardiovascular, neurodegenerative, oncological diseases and the development of type 2 diabetes mellitus. Although the pathogenesis of the metabolic syndrome has not yet been fully elucidated, it is known that visceral obesity and its associated complications, such as dyslipidemia and increased levels of pro-inflammatory cytokines, play a central role. The article presents data on the impact of the consumption of certain food products, the inclusion of plant biologically active substances (flavonoids, polyphenols, etc.) in the diet, as well as the use of elimination diets with the exclusion of carbohydrates or fats from the diet, on reducing the risk of cardiovascular accidents, levels of fasting glucose, total cholesterol, LDL, triglycerides, C-reactive protein, leptin, insulin, reduction in body weight and waist circumference, reduction in the level of circulating endotoxins and changes in the activity of immunocompetent cells. Data are presented on the possible influence of the intestinal microbiota in maintaining inflammation and the formation of degenerative changes in the body. The role of changes in the ratio of the levels of pathogenic microflora, bifidobacteria and lactobacilli in the formation of a pathological condition is shown.

Fortification of Chinese Steamed Bread with Glycyrrhizauralensis Polysaccharides and Evaluation of Its Quality and Performance Attributes

Natural polysaccharides are new popular healthy food material, and the materials are widely used in various functional foods. The influences of polysaccharides from Glycyrrhiza uralensis on the quality and sensory properties of Chinese steamed bread (CSB), as well as the performance (starch digestion in vitro and starch staling) of CSB, were investigated in this study. The addition of Glycyrrhiza polysaccharide (GP) increased the specific volume of CSB in a dose-dependent manner, and the specific volume of CSB-2 was 2.55 mL/g. GP also contributed to the increase in hardness (from 1240.17 to 2539.34 g) and chewiness (893.85 to 1959.27 g) of fresh CSB. In addition, GP could maintain the integrity of the protein network within the CSB. The scores for sensory evaluation indicators of CSB-1 were relatively balanced. More importantly, the addition of GP altered starch digestive properties, and the content of the resistant starch (RS) was increased from 8.62 (CSB-0) to 43.46% (CSB-2). GP led to a significant reduction of the expected glycemic index (eGI) of CSB, and the eGI of CSB was decreased from 97.50 (CSB-0) to 73.8 (CSB-2), which was classified as a medium-GI (MGI) food. In addition, X-ray diffraction (XRD) and differential scanning calorimeter (DSC) revealed the addition of GP delayed the staling of CSB during storage. In general, adding the proper amount of GP could improve the quality of CSB and show the potential as a functional component of CSB to reduce the postprandial blood glucose level resulted by the CSB.

Dietary Approaches and Health Outcomes: An Evidence Analysis Center Scoping Review

Appropriate diet can prevent, manage, or reverse noncommunicable health conditions such as obesity, cardiovascular disease, and diabetes. Consequently, the public's interest in diet and nutrition has fueled the multi-billion-dollar weight loss industry and elevated its standing on social media and the internet. Although many dietary approaches are popular, their universal effectiveness and risks across overall populations are not clear. The objective of this scoping review was to identify and characterize systematic reviews (SRs) examining diet or fasting (intermittent energy restriction [IER]) interventions among adults who are healthy or may have chronic disease. An in-depth literature search of six databases was conducted for SRs published between January 2010 and February 2020. A total of 22,385 SRs were retrieved, and 1,017 full-text articles were screened for eligibility. Of these, 92 SRs met inclusion criteria. Covered diets were organized into 12 categories: high/restricted carbohydrate (n = 30), Mediterranean, Nordic, and Tibetan (n = 19), restricted or modified fat (n = 17), various vegetarian diets (n = 16), glycemic index (n = 13), high protein (n = 12), IER (n = 11), meal replacements (n = 11), paleolithic (n = 8), Dietary Approaches to Stop Hypretension (DASH; n = 6), Atkins, South Beach, and Zone (n = 5), and eight other brand diets (n = 4). Intermediate outcomes, such as body weight or composition and cardiometabolic, were commonly reported. Abundant evidence was found exploring dietary approaches in the general population. However, heterogeneity of diet definitions, focus on single macronutrients, and infrequent macronutrient subanalyses were observed. Based on this scoping review, the Evidence Analysis Center prioritized the need to collate evidence related to macronutrient modification, specifically restricted carbohydrate diets.

The energy balance model of obesity: beyond calories in, calories out

A recent Perspective article described the "carbohydrate-insulin model (CIM)" of obesity, asserting that it "better reflects knowledge on the biology of weight control" as compared with what was described as the "dominant energy balance model (EBM)," which fails to consider "biological mechanisms that promote weight gain." Unfortunately, the Perspective conflated and confused the principle of energy balance, a law of physics that is agnostic as to obesity mechanisms, with the EBM as a theoretical model of obesity that is firmly based on biology. In doing so, the authors presented a false choice between the CIM and a caricature of the EBM that does not reflect modern obesity science. Here, we present a more accurate description of the EBM where the brain is the primary organ responsible for body weight regulation operating mainly below our conscious awareness via complex endocrine, metabolic, and nervous system signals to control food intake in response to the body's dynamic energy needs as well as environmental influences. We also describe the recent history of the CIM and show how the latest "most comprehensive formulation" abandons a formerly central feature that required fat accumulation in adipose tissue to be the primary driver of positive energy balance. As such, the new CIM can be considered a special case of the more comprehensive EBM but with a narrower focus on diets high in glycemic load as the primary factor responsible for common obesity. We review data from a wide variety of studies that address the validity of each model and demonstrate that the EBM is a more robust theory of obesity than the CIM.

Diets high in glycemic index and glycemic load are associated with an increased risk of metabolic syndrome among Korean women

BACKGROUND AND AIMS

Accurate estimation of the glycemic index (GI) and glycemic load (GL) of diets is essential when assessing health implications of dietary GI and GL. The present study aimed to estimate dietary GI and GL utilizing the updated GI tables with a large number of new, reliable GI values and assess their associations with metabolic syndrome among Korean adults.

METHODS AND RESULTS

We analyzed data from 3317 men and 6191 women for this cross-sectional study. Dietary intake was assessed with a validated food frequency questionnaire. Metabolic syndrome and its components were defined based on the harmonized criteria with Korean-specific cutoffs for waist circumference. Multivariate logistic regression was used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs). Compared with women in the lowest quintiles of energy-adjusted dietary GI and GL, women in the highest quintiles had significantly greater risks of metabolic syndrome (GI, OR = 1.56, 95% CI = 1.18-2.06; GL, OR = 1.80, 95% CI = 1.27-2.57), elevated blood pressure, reduced high-density lipoprotein cholesterol (HDL-C, both GI and GL), elevated triglycerides (GI only), elevated waist circumference, and elevated fasting glucose (GL only). Among men, no significant association was noted except for a higher risk of reduced HDL-C (OR = 1.59, 95% CI = 1.01-2.29) in the highest quintile of energy-adjusted dietary GI than in the lowest quintile.

CONCLUSION

Our findings suggest that dietary GI and GL are positively associated with metabolic syndrome risk among women, but not men, in Korea.

Habitual- and Meal-Specific Carbohydrate Quality Index and Their Relation to Metabolic Syndrome in a Sample of Iranian Adults

AIM

Most studies on diet quality have focused on the habitual and overall intake of foods without considering intakes at specific eating occasions. This study aimed to assess the association between habitual- and meal-specific carbohydrate quality index (CQI) and metabolic syndrome (MetS) in Iranian adults.

METHODS

In this cross-sectional study, data from 850 participants were analyzed. Dietary information was obtained from a 3-day nonconsecutive 24 h recall. CQI was calculated from three criteria: dietary fiber, glycemic index, and solid carbohydrate/total carbohydrate ratio. The association between CQI and MetS was assessed by logistic regression.

RESULTS

The prevalences of MetS in the lowest and highest tertile of CQI were 30.1 and 33.7, respectively (P = 0.6). In habitual diet and all the three meals, we failed to find any significant association between tertiles of CQI and MetS either before or after adjustment for covariates. However, in the habitual meals [odds ratio (OR): 0.69, 95% CI: 0.47-0.96] and lunch meals (OR: 0.66; 95% CI: 0.47-0.94), the highest CQI in comparison to the lowest one, significantly decreased the low high-density lipoprotein (HDL). In addition, the trend of low-HDL with CQI in habitual meal and lunch meal was statistically significant.

CONCLUSION

The results of this study showed that CQI was not associated with MetS and its components. Further investigations into the mechanisms underlying the role of carbohydrate quality in developing metabolic disorders are warranted.

Dietary Complex and Slow Digestive Carbohydrates Promote Bone Mass and Improve Bone Microarchitecture during Catch-Up Growth in Rats

Catch-up growth is a process that promotes weight and height gains to recover normal growth patterns after a transient period of growth inhibition. Accelerated infant growth is associated with reduced bone mass and quality characterized by poor bone mineral density (BMD), content (BMC), and impaired microarchitecture. The present study evaluated the effects of a diet containing slow (SDC) or rapid (RDC) digestible carbohydrates on bone quality parameters during the catch-up growth period in a model of diet-induced stunted rats. The food restriction period negatively impacted BMD, BMC, and microarchitecture of appendicular and axial bones. The SDC diet was shown to improve BMD and BMC of appendicular and axial bones after a four-week refeeding period in comparison with the RDC diet. In the same line, the micro-CT analysis revealed that the trabecular microarchitecture of tibiae and vertebrae was positively impacted by the dietary intervention with SDC compared to RDC. Furthermore, features of the cortical microstructure of vertebra bones were also improved in the SDC group animals. Similarly, animals allocated to the SDC diet displayed modest improvements in growth plate thickness, surface, and volume compared to the RDC group. Diets containing the described SDC blend might contribute to an adequate bone formation during catch-up growth thus increasing peak bone mass, which could be linked to reduced fracture risk later in life in individuals undergoing transient undernutrition during early life.

A Digital Health Application Allowing a Personalized Low-Glycemic Nutrition for the Prophylaxis of Migraine: Proof-of-Concept Data from a Retrospective Cohort Study

Background: Migraine is a headache disorder with the highest socioeconomic burden. The aim of this study was to deliver the first proof-of-concept data of the potential role of an individual low-glycemic diet provided by a novel digital health application in the prophylaxis of migraine. Methods: We analyzed data from a retrospective survey of individuals who participated in a digital nutrition program that provides dietary recommendations based on the individual analysis of continuous glucose measurement from an up to 14-day test phase. A total of 84 individuals completed the retrospective digital survey. The endpoints were changes in the number of migraine days, average duration of attacks, average pain severity, frequency of intake of pain medication, absenteeism, and presenteeism before and after program participation. Results: The intraindividual comparisons of the endpoints before and after program participation revealed decreases in migraine frequency and other patient-relevant migraine parameters. Moreover, patients with a baseline migraine frequency of two and more migraine days per month and adherence to the dietary recommendations (n = 40) showed a mean reduction in migraine days by 33% with a 50%-responder rate of 38%. Conclusions: The data provides emerging evidence that an individualized low-glycemic diet based on continuous glucose measurement could be a promising approach for a diet-based, non-pharmacological migraine prophylaxis. However, future research is required to confirm the implied effectiveness.

Dietary Inflammatory Index in relation to Type 2 Diabetes: A Meta-Analysis

BACKGROUND AND AIMS

Epidemiologic studies show a strong association between chronic inflammation and type 2 diabetes (T2D). Diet may also affect the risk of T2D by modulating inflammation. This meta-analysis aimed to assess the relation of dietary inflammatory index (DII) and risk of T2D.

METHODS

PubMed and Scopus were systematically searched from their inception to September 2020 to identify relevant studies. Relative risks, hazard ratios, or odds ratios (OR), with their corresponding 95% confidence intervals (95% CI), were calculated and pooled using a random-effects model.

RESULTS

A total of 48 different studies, with a total sample size of 1,687,424 participants, were eligible to be included in this meta-analysis. In the overall analysis, no significant association was observed between DII and risk of T2D (OR = 1.03, 95% CI: 0.91 to 1.15), with significant evidence for heterogeneity (I 2  = 96.5%, P < 0.001); however, higher DII was identified as being significantly related to increased risk of T2D in high quality studies (OR = 1.58, 95% CI: 1.15 to 2.17). In the stratified analysis by the dietary assessment tool, background disease, and sex of participants, DII showed no significant association with T2D.

CONCLUSIONS

Higher DII might be associated with an increased risk of T2D. Additional well-designed studies are required to confirm this finding.

Effects of personalized diets by prediction of glycemic responses on glycemic control and metabolic health in newly diagnosed T2DM: a randomized dietary intervention pilot trial

BACKGROUND

Dietary modifications are crucial for managing newly diagnosed type 2 diabetes mellitus (T2DM) and preventing its health complications, but many patients fail to achieve clinical goals with diet alone. We sought to evaluate the clinical effects of a personalized postprandial-targeting (PPT) diet on glycemic control and metabolic health in individuals with newly diagnosed T2DM as compared to the commonly recommended Mediterranean-style (MED) diet.

METHODS

We enrolled 23 adults with newly diagnosed T2DM (aged 53.5 ± 8.9 years, 48% males) for a randomized crossover trial of two 2-week-long dietary interventions. Participants were blinded to their assignment to one of the two sequence groups: either PPT-MED or MED-PPT diets. The PPT diet relies on a machine learning algorithm that integrates clinical and microbiome features to predict personal postprandial glucose responses (PPGR). We further evaluated the long-term effects of PPT diet on glycemic control and metabolic health by an additional 6-month PPT intervention (n = 16). Participants were connected to continuous glucose monitoring (CGM) throughout the study and self-recorded dietary intake using a smartphone application.

RESULTS

In the crossover intervention, the PPT diet lead to significant lower levels of CGM-based measures as compared to the MED diet, including average PPGR (mean difference between diets, - 19.8 ± 16.3 mg/dl × h, p < 0.001), mean glucose (mean difference between diets, - 7.8 ± 5.5 mg/dl, p < 0.001), and daily time of glucose levels > 140 mg/dl (mean difference between diets, - 2.42 ± 1.7 h/day, p < 0.001). Blood fructosamine also decreased significantly more during PPT compared to MED intervention (mean change difference between diets, - 16.4 ± 37 μmol/dl, p < 0.0001). At the end of 6 months, the PPT intervention leads to significant improvements in multiple metabolic health parameters, among them HbA1c (mean ± SD, - 0.39 ± 0.48%, p < 0.001), fasting glucose (- 16.4 ± 24.2 mg/dl, p = 0.02) and triglycerides (- 49 ± 46 mg/dl, p < 0.001). Importantly, 61% of the participants exhibited diabetes remission, as measured by HbA1c < 6.5%. Finally, some clinical improvements were significantly associated with gut microbiome changes per person.

CONCLUSION

In this crossover trial in subjects with newly diagnosed T2DM, a PPT diet improved CGM-based glycemic measures significantly more than a Mediterranean-style MED diet. Additional 6-month PPT intervention further improved glycemic control and metabolic health parameters, supporting the clinical efficacy of this approach.

TRIAL REGISTRATION

ClinicalTrials.gov number, NCT01892956.

Associations of Glycemic Index and Glycemic Load with Cardiovascular Disease: Updated Evidence from Meta-analysis and Cohort Studies

PURPOSE OF REVIEW

Diet and lifestyle patterns are considered major contributory factors for cardiovascular disease (CVD) and mortality. In particular, consuming a diet higher in carbohydrates (not inclusive of fruits and vegetables, but more processed carbohydrates) has been associated with metabolic abnormalities that subsequently may increase the risk of CVD and related mortality. Glycemic index (GI) and glycemic load (GL) are values given to foods based on how fast the body converts carbohydrates into glucose also referred to as the glycemic burden of carbohydrates from foods. Conflicting associations of how high GI and GL influence CVDs have been observed even in high-quality meta-analysis studies. We synthesize and report the associations of high GI and GL with various CVDs by sex, obesity, and geographical locations using an updated review of meta-analysis and observational studies.

RECENT FINDINGS

We identified high GI or high GL is associated with an increased risk of CVD events including diabetes (DM), metabolic syndrome (MS), coronary heart disease (CHD), stroke, and stroke mortality in the general population, and the risk of CVD outcomes appears to be stratified by sex, obesity status, and preexisting CVD. Both high GI and GL are associated with DM and CHD in the general population. However, high GI is strongly associated with DM/MS, while high GL is strongly associated with an increased risk of CHD in females. In addition, high GL is also associated with incident stroke, and appears to be associated with CVD mortality in subjects with preexisting CVD or high BMI and all-cause mortality in non-obese DM subjects. However, high GI appears to be associated with CVD or all-cause mortality only in females without CVD. High GI/GL is an important risk factor for CVD outcomes in the general population. High GI seems to be markedly associated with DM/MS, and it may enhance the risk of CVD or all-cause mortality in both sexes and predominately females. Although both high GI and high GL are risk factors for CHD in females, high GL is associated with CVD outcomes in at-risk populations for CVD. These data suggest that while high GI increases the propensity of CVD risk factors and mortality in healthy individuals, high GL contributes to the risk of severe heart diseases including CVD or all-cause mortality, particularly in at-risk populations. These data indicate dietary interventions designed for focusing carbohydrate quality by lowering both GI and GL are recommended for preventing CVD outcomes across all populations.

Assessing Long-Term Impact of Dietary Interventions on Occurrence of Symptoms Consistent with Hypoglycemia in Patients without Diabetes: A One-Year Follow-Up Study

Background: A well-balanced nutritional diet pattern has a significant role in the management of diet-related disorders. Currently, there are no specific dietary guidelines to refer to when advising non-diabetic patients with symptoms attributed to hypoglycemia in the postprandial period or patients with confirmed reactive hypoglycemia (RH). The aim of this study was to investigate the impact of the dietary interventions, and their sustained outcome, on the severity of hypoglycemic-like symptoms occurring in non-diabetic patients. Methods: The study group included forty non-diabetic individuals with symptoms consistent with RH. At the baseline, each patient underwent RH diagnosis and complex dietary evaluation. Over a period of six months, each patient had four appointments with a dietitian. Two sessions were focused on a dietary education about low glycemic index diet (LGID) and Mediterranean diet (MD). The said diets were to be followed for a period of three months, with two additional dietary check-ups. Once dietary supervision was completed, patients had no imposed dietary patterns. The final follow-up appointment took place twelve months later and that is when each patient underwent a detailed assessment of their current dietary habits and evaluation of the frequency of symptoms consistent with hypoglycemia. Results: There was a statistically significant reduction in the severity in eight out of the ten analyzed hypoglycemic-like symptoms after the dietary interventions. The most significant change was observed in the following symptoms: hunger (η2 = 0.66), impaired concentration (η2 = 0.61), hand tremor (η2 = 0.55), and fatigue (η2 = 0.51). The outcomes were comparable for both recommended diets, the LGID and the MD. The reduction in hypoglycemic-like symptoms continued after the twelve-month period. The individualized dietary counselling significantly improved the patients’ eating habits in comparison to those present prior to intervention in terms of healthy diet index (F(2,78) = 27.30, p < 0.001, η2 = 0.41, 90%CI [0.26; 0.51]) and unhealthy diet index (F(2,78) = 433.39, p < 0.001, η2 = 0.91, 90%CI [0.89; 0.93]). Conclusions: Healthy modifications in dietary habits may improve patient’s well-being and reduce the severity of their postprandial symptoms attributed to hypoglycemia. Therefore, dietary intervention focused on appropriate nutritional management combined with follow-up consultations may be a beneficial step towards comprehensive treatment of non-diabetic patients who present with hypoglycemic-like symptoms in the postprandial period.

Low-Glycemic Index Diets as an Intervention in Metabolic Diseases: A Systematic Review and Meta-Analysis

We aimed to investigate the effects of a low-glycemic index (GI) diet on the body mass and blood glucose of patients with four common metabolic diseases by conducting a systematic review and meta-analysis of studies comparing a low-GI diet (LGID) and other types of diet. Search terms relating to population, intervention, comparator, outcomes, and study design were used to search three databases: PubMed, Embase, and the Cochrane Library. We identified 24 studies involving 2002 participants. Random-effects models were used for 16 studies in the meta-analysis and stratified analyses were performed according to the duration of the intervention. The systematic review showed that LGIDs slightly reduced body mass and body mass index (BMI) (p < 0.05). BMI improved more substantially after interventions of >24 weeks and there was no inter-study heterogeneity (I² = 0%, p = 0.48; mean difference (MD) = -2.02, 95% confidence interval (CI): -3.05, -0.98). Overall, an LGID had superior effects to a control diet on fasting blood glucose (FBG) and glycosylated hemoglobin. When the intervention exceeded 30 days, an LGID reduced FBG more substantially (MD = -0.34, 95% CI: -0.55, -0.12). Thus, for patients with metabolic diseases, an LGID is more effective at controlling body mass and blood glucose than a high-GI or other diet.

Using Dietary Macronutrient Patterns to Predict Sarcopenic Obesity in Older Adults: A Representative Korean Nationwide Population-Based Study

Older adults with sarcopenic obesity (SO) are at increased risk of adverse health outcomes. It has not been identified which pattern of macronutrient intake is appropriate in relation to SO. We aimed to compare the patterns of macronutrient intake for predicting SO in older adults. Data from a total of 3828 older adults who participated in the 2008–2011 Korea National Health and Nutrition Examination Survey were analyzed. The one-day 24 h dietary recall method was used to assess macronutrient intake. SO was defined by a combination of body mass index (BMI) ≥ 25 kg/m² and BMI adjusted-appendicular skeletal muscle mass <0.789 for men and <0.512 for women. Weighted logistic regression analysis revealed the odds ratio (95% confidence interval) for SO of total calorie intake per 100 increments and carbohydrate (CHO) intake (g/kg/day) per 1 increment to be 0.95 (0.91–0.99) and 0.83 (0.74–0.94), respectively, after adjusting for confounding variables in women. The predictive power for SO of CHO intake (g/kg/day) was higher compared with the other patterns of macronutrient intake both in men and women. In conclusion, total calorie intake and CHO intake (g/kg/day) are inversely related to SO in women. CHO intake (g/kg/day) could be the best index for determining SO.

Glycemic index, but not glycemic load, is associated with an increased risk of metabolic syndrome: Meta-analysis of observational studies

BACKGROUND

Diets with high glycemic index (GI) or high glycemic load (GL) have been linked to important risk factors associated with the development of metabolic syndrome (MetS), such as dyslipidemia, higher blood glucose, and insulin concentrations. However, the role of GI and GL in relation to Mets is still understudied and controversial. This review, therefore, assessed whether high GI or GL contribute to development of Mets.

METHODS

A systematic search of four bibliographic databases was conducted (MEDLINE/PubMed, EMBASE, Web of Sciences, and Scopus) from inception to January 2020 for observational studies assessing GI/GL in relation to MetS. Risk estimates were pooled using random-effect models for the highest versus lowest intake categories, and assessed for heterogeneity using subgroup analysis. The dose-response nature of the relationship was also investigated. Sensitivity analysis and Egger test were used to check the robustness of findings and the possibility of publication bias, respectively.

RESULTS

Data from 12 publications (one cohort study and eleven cross-sectional studies) with a total sample size of 36,295 subjects are included. The pooled effect sizes from the nine studies indicated high versus low dietary GI was associated with increased risk of MetS (OR = 1.05, 95% CI: 1.01 to 1.09) (I²  = 58.1, P = .004). This finding was supported by all subgroup analyses except where studies used 24-h recalls for dietary assessment. Additionally, a linear dose-response investigation revealed that each 5-point increment in GI was associated with 2% increase in the risk of MetS (OR = 1.02, 95% CI: 1.01 to 1.02); non-linear pattern was insignificant, however (p-nonlinearity = 0.63). Moreover, pooled effect sizes from ten studies suggested that no association was found between the GL and MetS with results remaining consistent in all subgroup analyses.

CONCLUSION

A diet with lower GI may protect against MetS. Nutrition policy and clinical practices should encourage a diet with low GI. Future studies should include both GI and GL and different criteria of MetS to provide a better comparison.

Personalized Postprandial Glucose Response-Targeting Diet Versus Mediterranean Diet for Glycemic Control in Prediabetes

OBJECTIVE

To compare the clinical effects of a personalized postprandial-targeting (PPT) diet versus a Mediterranean (MED) diet on glycemic control and metabolic health in prediabetes.

RESEARCH DESIGN AND METHODS

We randomly assigned adults with prediabetes (n = 225) to follow a MED diet or a PPT diet for a 6-month dietary intervention and additional 6-month follow-up. The PPT diet relies on a machine learning algorithm that integrates clinical and microbiome features to predict personal postprandial glucose responses. During the intervention, all participants were connected to continuous glucose monitoring (CGM) and self-reported dietary intake using a smartphone application.

RESULTS

Among 225 participants randomized (58.7% women, mean ± SD age 50 ± 7 years, BMI 31.3 ± 5.8 kg/m², HbA_1c, 5.9 ± 0.2% [41 ± 2.4 mmol/mol], fasting plasma glucose 114 ± 12 mg/dL [6.33 ± 0.67 mmol/L]), 200 (89%) completed the 6-month intervention. A total of 177 participants also contributed 12-month follow-up data. Both interventions reduced the daily time with glucose levels >140 mg/dL (7.8 mmol/L) and HbA_1c levels, but reductions were significantly greater in PPT compared with MED. The mean 6-month change in "time above 140" was -0.3 ± 0.8 h/day and -1.3 ± 1.5 h/day for MED and PPT, respectively (95% CI between-group difference -1.29 to -0.66, P < 0.001). The mean 6-month change in HbA_1c was -0.08 ± 0.19% (-0.9 ± 2.1 mmol/mol) and -0.16 ± 0.24% (-1.7 ± 2.6 mmol/mol) for MED and PPT, respectively (95% CI between-group difference -0.14 to -0.02, P = 0.007). The significant between-group differences were maintained at 12-month follow-up. No significant differences were noted between the groups in a CGM-measured oral glucose tolerance test.

CONCLUSIONS

In this clinical trial in prediabetes, a PPT diet improved glycemic control significantly more than a MED diet as measured by daily time of glucose levels >140 mg/dL (7.8 mmol/L) and HbA_1c. These findings may have implications for dietary advice in clinical practice.

Perspective: Does Glycemic Index Matter for Weight Loss and Obesity Prevention? Examination of the Evidence on "Fast" Compared with "Slow" Carbs

High-glycemic index (high-GI) foods (so-called fast carbs) have been hypothesized to promote fat storage and increase risk of obesity. To clarify whether dietary GI impacts body weight, we searched PubMed and the Cochrane Database of Systematic Reviews for observational studies reporting associations between BMI and dietary GI, and for meta-analyses of randomized controlled trials (RCTs) comparing low-GI and high-GI diets for weight loss. Data on 43 cohorts from 34 publications, totaling 1,940,968 adults, revealed no consistent differences in BMI when comparing the highest with the lowest dietary GI groups. In the 27 cohort studies that reported results of statistical comparisons, 70% showed that BMI was either not different between the highest and lowest dietary GI groups (12 of 27 cohorts) or that BMI was lower in the highest dietary GI group (7 of 27 cohorts). Results of 30 meta-analyses of RCTs from 8 publications demonstrated that low-GI diets were generally no better than high-GI diets for reducing body weight or body fat. One notable exception is that low-GI diets with a dietary GI at least 20 units lower than the comparison diet resulted in greater weight loss in adults with normal glucose tolerance but not in adults with impaired glucose tolerance. While carbohydrate quality, including GI, impacts many health outcomes, GI as a measure of carbohydrate quality appears to be relatively unimportant as a determinant of BMI or diet-induced weight loss. Based on results from observational cohort studies and meta-analyses of RCTs, we conclude that there is scant scientific evidence that low-GI diets are superior to high-GI diets for weight loss and obesity prevention.

Effect of low glycaemic index or load dietary patterns on glycaemic control and cardiometabolic risk factors in diabetes: systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To inform the update of the European Association for the Study of Diabetes clinical practice guidelines for nutrition therapy.

DESIGN

Systematic review and meta-analysis of randomised controlled trials.

DATA SOURCES

Medline, Embase, and the Cochrane Library searched up to 13 May 2021.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised controlled trials of three or more weeks investigating the effect of diets with low glycaemic index (GI)/glycaemic load (GL) in diabetes.

OUTCOME AND MEASURES

The primary outcome was glycated haemoglobin (HbA1c). Secondary outcomes included other markers of glycaemic control (fasting glucose, fasting insulin); blood lipids (low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), non-HDL-C, apo B, triglycerides); adiposity (body weight, BMI (body mass index), waist circumference), blood pressure (systolic blood pressure (SBP) and diastolic blood pressure (DBP)), and inflammation (C reactive protein (CRP)).

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers extracted data and assessed risk of bias. Data were pooled by random effects models. GRADE (grading of recommendations assessment, development, and evaluation) was used to assess the certainty of evidence.

RESULTS

29 trial comparisons were identified in 1617 participants with type 1 and 2 diabetes who were predominantly middle aged, overweight, or obese with moderately controlled type 2 diabetes treated by hyperglycaemia drugs or insulin. Low GI/GL dietary patterns reduced HbA1c in comparison with higher GI/GL control diets (mean difference −0.31% (95% confidence interval −0.42 to −0.19%), P<0.001; substantial heterogeneity, I2=75%, P<0.001). Reductions occurred also in fasting glucose, LDL-C, non-HDL-C, apo B, triglycerides, body weight, BMI, systolic blood pressure (dose-response), and CRP (P<0.05), but not blood insulin, HDL-C, waist circumference, or diastolic blood pressure. A positive dose-response gradient was seen for the difference in GL and HbA1c and for absolute dietary GI and SBP (P<0.05). The certainty of evidence was high for the reduction in HbA1c and moderate for most secondary outcomes, with downgrades due mainly to imprecision.

CONCLUSIONS

This synthesis suggests that low GI/GL dietary patterns result in small important improvements in established targets of glycaemic control, blood lipids, adiposity, blood pressure, and inflammation beyond concurrent treatment with hyperglycaemia drugs or insulin, predominantly in adults with moderately controlled type 1 and type 2 diabetes. The available evidence provides a good indication of the likely benefit in this population.

STUDY REGISTRATION

ClinicalTrials.gov NCT04045938.

Evaluation of glycemic index, antioxidant capacity, and metabolic effects of a fermented beverage made from Changbai Mountain fruit and vegetables

Fermented foods and beverages have been known to be beneficial when included in the human diet. This study examined the glycemic index (GI) of a fermented beverage (FB) made from Changbai Mountain fruit and vegetables in humans and its antioxidant capacity and metabolic effects in a rat model of diabetes. Twenty healthy volunteers were tested with 50 g of glucose and 50 g equivalent of carbohydrates from FB on two separate days for GI measurement. The rats were randomly divided into blank control group (n = 15) and diabetic model (DM) group (n = 75). DM group were randomly divided into five groups, positive control group, model control group and three FB treatment (2.5, 5, 10 ml/kg·bw·d) groups. The general indices, including blood glucose and lipid levels and antioxidant index, of the rats were measured to investigate the effect of FB. The GI of FB was found to be 56.99, indicating it as a medium GI food. Compared to model control group, the low-dose FB group had lower blood glucose levels and higher high-density lipoprotein cholesterol levels in DM rats (p < .05). Medium- and high-dose FB decreased the serum malonaldehyde levels in DM rats compared to those in the model control group. The FB-treated DM rat groups showed increased serum glutathione and superoxide dismutase levels compared with those in the model control group (p < .05). FB is a medium GI food that plays a protective role against oxidative stress in DM rats. PRACTICAL APPLICATIONS: The present study evaluated the glycemic index of a fermented beverage (FB) made from Changbai Mountain fruit and vegetables in humans and investigated its antioxidant capacity and metabolic effects in a rat diabetes model. The study results may aid in the development of FB from fruits and vegetables and provide a theoretical basis for further research and development.

Diet pattern may affect fasting insulin in a large sample of black and white adults

OBJECTIVE

Dietary modification of insulin resistance may be a strategy for reducing chronic disease. For this study, we tested the hypothesis that higher fasting insulin, a marker for insulin resistance, would be related to diet patterns with a high proportion of carbohydrates, those with a high glycemic index, and those characterized by added sugar and processed starches.

STUDY DESIGN

Data were analyzed on 13,528 nondiabetic participants of the REasons for Geographic and Ethnic Differences in Stroke (REGARDS), an observational study of adults aged ≥45 years residing in 1855 counties across the continental USA. Information on habitual diet was collected using the Block 98 Food Frequency Questionnaire. Percent energy from carbohydrate, glycemic index, and glycemic load were determined for each participant, as well as adherence to five established diet patterns. Logistic regression was used to examine associations of baseline diet characteristics with odds for high fasting insulin [quartiles 3 and 4 (median = 98.9 pmol/L) vs. quartile 1], after adjusting for covariates.

RESULT

Greater percent carbohydrate, glycemic index, and glycemic load, and adherence to sweets/fat and southern diet patterns, was associated with greater odds for high insulin (P for trend <0.05 to <0.0001), whereas adherence to the plant-based and alcohol/salad patterns was associated with lower odds for high insulin (P for linear trend <0.0001).

CONCLUSION

In conclusion, diet pattern is associated with fasting insulin. Future studies are needed to determine if diet interventions designed to lower insulin, perhaps based on the patterns identified in this study, can improve risk for chronic disease.

A Powerful HPLC-ELSD Method for Simultaneous Determination of Fecal Bile Acids in T2DM Rats Interfered by Sanhuang Xiexin Tang

Bile acids (BAs) as important endogenous ligands can activate farnesoid X receptor (FXR) and G-protein-coupled bile acid receptor 1 (GPBAR1, also known as TGR5) signaling to regulate glycolipid metabolism. In this study, a simple, reliable and sensitive analysis method for simultaneous determination of four BAs from rat feces based on high-performance liquid chromatography with evaporative light scattering detector (HPLC-ELSD) was developed. Chromatographic analysis was performed with the mobile phases of acetonitrile and 0.2% formic acid. All the standard curves exhibited good linearity (R2 ≥ 0.99). The relative standard deviations of precision, stability and repeatability varied from 1.27 to 3.96%, 2.20 to 3.89% and 3.00 to 4.31%, respectively. The validated method was successfully applied to investigate the variation of four BAs in feces from T2DM rats after oral administration of Sanhuang Xiexin Tang (SXT). Data showed that SXT could remarkably increase the contents of conjunct BAs and decrease the contents of free BAs, which might contribute to ameliorate the symptoms of T2DM rats.