Glycemic index, glycemic load, and blood pressure: a systematic review and meta-analysis of randomized controlled trials

Macronutrients and cardiovascular diseases: A narrative review of recent scientific literature

BACKGROUND & AIMS

Cardiovascular diseases (CVDs) are the leading cause of mortality worldwide. This narrative review explores the relationship between macronutrient intake and CVD risk, focusing on carbohydrates, proteins, and fats. The goal is to examine how specific types of macronutrients influence cardiovascular health and how dietary guidelines, such as those from the World Health Organization (WHO), can reduce the incidence of both fatal and non-fatal cardiovascular events.

METHODS

This narrative review draws upon existing research and WHO dietary guidelines to assess the impact of various macronutrients on cardiovascular outcomes. We searched the relevant literature up to December 2024 using Pubmed and Google Scholar. Key macronutrient groups-carbohydrates (with a focus on glycemic index and glycemic load), proteins (plant-based vs. animal-based), and fats (saturated, trans, polyunsaturated, and monounsaturated)-were analyzed to understand their roles in CVD prevention.

RESULTS

Low glycemic index (GI) and glycemic load (GL) were found to be associated with reduced CVD risk. Protein intake showed no significant direct association with CVD risk, but higher consumption of plant-based proteins was correlated with a reduced risk. Replacing animal proteins with plant-based alternatives led to improved lipid profiles, including reductions in total and low-density lipoprotein (LDL) cholesterol levels. Fats, particularly saturated and trans fats, were strongly linked to increased CVD risk. WHO guidelines recommend limiting these fats and replacing them with healthier alternatives, such as polyunsaturated and monounsaturated fats or slow-digesting carbohydrates, to lower CVD risk.

CONCLUSIONS

Macronutrients play a critical role in cardiovascular health, with specific types of carbohydrates, proteins, and fats having varying impacts on CVD risk. Future research should explore the complex interactions between these macronutrients, dietary patterns, and cultural factors to optimize global dietary guidelines for CVD prevention. Replacing high-GI carbohydrates, saturated fats, and trans fats with healthier alternatives is crucial for reducing cardiovascular risk globally.

Relationship between TyG-BMI index and glycemic index with diet quality, anthropometric indices, and blood pressure in patients with metabolic syndrome

A recently introduced metric for assessing metabolic syndrome (MetS) is the triglyceride glucose-body mass index (TyG-BMI). Additionally, the glycemic index (GI) is recognized as a significant measure for evaluating conditions associated with blood glucose. In this context, our research explores the correlation between TyG-BMI and GI in relation to diet quality, anthropometric measurements, and blood pressure among individuals diagnosed with MetS. A cross-sectional descriptive-analytical study was conducted on 431 employees with MetS at Shiraz University of Medical Sciences (SUMS). Anthropometric measurements of height, weight, waist circumference (WC), and hip circumference (HC) were taken according to Persian cohort protocols. BMI, C-index, visceral adiposity index (VAI), body adiposity index (BAI), body shape index (ABSI), abdominal volume index (AVI), potential renal acid load (PRAL), TyG-BMI and GI were calculated. A physician measured blood pressure, while the dietary inflammatory index was determined using guidelines. Biochemical parameters were analyzed using standard laboratory techniques. Data analysis was conducted using SPSS software version 21, with a significance threshold set at <.05. A significant correlation was identified between the TyG-BMI index and the PRAL index (β = 0.094, P-value = .026), WC (β = 0.627, P-value < .001), BAI (β = 0.396, P-value < .001), and blood pressure (β = 0.063, P-value = .002). Furthermore, the findings indicated a notable association between the GI and blood pressure (β = 0.610, P-value < .001). The results of this study suggest that managing the PRAL index, body weight, and blood pressure may be associated with an enhanced status of TyG-BMI. Additionally, appropriate GI may be linked to regulated blood pressure. These findings can inform health-related policy decisions for these patients.

Assessing the Hypertension Risk: A Deep Dive into Cereal Consumption and Cooking Methods-Insights from China

BACKGROUND

Cereal grains are rich in carbohydrates and could trigger a hyperglycemic response which is closely linked to blood pressure status. We aim to examine the associations between the consumption of cereals with different cooking methods and hypertension risk.

METHODS

We conducted a prospective analysis utilizing the nationwide data of 11,080 adult participants who were free of hypertension at baseline. Cereal intake was assessed using 3-day 24 h dietary recalls with a weighing technique. Hypertension incidence was identified in adherence with the Seventh Joint National Commission guidelines during the follow-up. Cox proportional hazards regression models were used to extrapolate hazard ratios associated with hypertension risk.

RESULTS

Over an average follow-up span of 7 years (77,560 person-years), we identified 3643 new hypertension cases. The intake of total, fried, and baked cereals was associated with 15%, 20%, and 20% higher risk of hypertension, respectively. Whole grain consumers had an 8% lower risk of hypertension compared with non-consumers, while total refined grain consumers showed no significant association. Replacing one daily serving of fried or baked cereals with an equivalent serving of boiled cereals was related to a 28% or 14% lower risk, respectively.

CONCLUSIONS

Total, fried, and baked cereal consumption was positively associated with hypertension risk, while consuming whole grains was related to a lower risk. Modifying cooking methods from frying or baking to boiling for cereals may be beneficial to lower risk. The current study underscores the significance of considering both the degree of processing and cooking methods applied to cereals in addressing hypertension prevention and management.

The effect of flour-based foods intake in the reduction of cardiometabolic risk: A systematic review

Cardiometabolic risk triggers a state of chronic and subclinical inflammation, conferring a higher risk of morbidity and mortality. Thus, minimal processing of foods with high nutritional value, in the form of flour, becomes an effective dietary strategy in preventing and treating cardiometabolic risk factors. This systematic review aims to evaluate the evidence on the effect of flour-based food intake on reducing the most common cardiometabolic risk factors. We included all randomized controlled trials published up to April 2023 in the main databases PubMed, Scopus and Web of Science. Eleven clinical trials were included. The amount of flour used in the studies ranged from 1.5 g to 36 g/day, and the supplementation period ranged from six weeks to 120 days. Green jackfruit flour, green banana flour, soy flour, flour from rind of the yellow passion fruit, and fenugreek powder demonstrated significant results in improve parameters of glucose homeostasis. Chia flour, green banana flour, soy flour, and fenugreek powder showed improvements in blood pressure measurements. Brazil nut flour and chia flour reduced total cholesterol. Chia flour also increased HDL cholesterol levels. The evidence presented in the current systematic review indicates that flour-derived foods intake is related to improve cardiometabolic risk factors parameters.

Effects on cardiovascular risk factors of a low- vs high-glycemic index Mediterranean diet in high cardiometabolic risk individuals: the MEDGI-Carb study

BACKGROUND

The role of dietary Glycemic Index (GI), independently of fiber intake, in modulating cardiovascular disease (CVD) risk among non-diabetic individuals has not been fully elucidated.

OBJECTIVE

To evaluate the effects of a low- versus a high-GI diet, based on a Mediterranean dietary pattern, on cardiometabolic risk factors in individuals at high CVD risk, participating in the MEDGI-Carb intervention study.

SUBJECTS AND METHODS

160 individuals, aged 30-69 years, BMI 25-37 kg/m2, with a waist circumference >102 cm (males) or >88 cm (females) and one feature of the metabolic syndrome, participated in a multi-national (Italy, Sweden, USA) randomized controlled parallel group trial. Participants were assigned to a low GI (< 55) or high-GI MedDiet ( > 70) for 12 weeks. The diets were isoenergetic and similar for available carbohydrate (270 g/d) and fiber (35 g/d) content. Fasting metabolic parameters were evaluated in the whole cohort, while an 8-h triglyceride profile (after standard breakfast and lunch) was evaluated only in the Italian cohort.

RESULTS

Blood pressure and most fasting metabolic parameters improved at the end of the dietary intervention (time effect, p < 0.05 for all); however, no differences were observed between the low- and the high-GI MedDiet groups (time x group effect; p > 0.05 for all). Conversely, the low-GI diet, compared with high-GI diet, significantly reduced the 8-h triglyceride profile (p < 0.017, time*group effect) that was measured only in the Italian cohort. However, it induced a reduction of plasma triglycerides after lunch (tAUC) that was of only borderline statistically significance (p = 0.065).

CONCLUSIONS

Consuming a low-GI in comparison with a high-GI MedDiet does not differentially affect the major cardiometabolic risk factors at fasting in individuals at increased cardiometabolic risk. Conversely, it could reduce postprandial plasma triglycerides.

CLINICAL TRIAL REGISTRY NUMBER

NCT03410719, ( https://clinicaltrials.gov ).

Dietary Assessment and Metabolomic Methodologies in Human Feeding Studies: A Scoping Review

Dietary metabolomics is a relatively objective approach to identifying new biomarkers of dietary intake and for use alongside traditional methods. However, methods used across dietary feeding studies vary, thus making it challenging to compare results. The objective of this study was to synthesize methodological components of controlled human feeding studies designed to quantify the diet-related metabolome in biospecimens, including plasma, serum, and urine after dietary interventions. Six electronic databases were searched. Included studies were as follows: 1) conducted in healthy adults; 2) intervention studies; 3) feeding studies focusing on dietary patterns; and 4) measured the dietary metabolome. From 12,425 texts, 50 met all inclusion criteria. Interventions were primarily crossover (n = 25) and parallel randomized controlled trials (n = 22), with between 8 and 395 participants. Seventeen different dietary patterns were tested, with the most common being the "High versus Low-Glycemic Index/Load" pattern (n = 11) and "Typical Country Intake" (n = 11); with 32 providing all or the majority (90%) of food, 16 providing some food, and 2 providing no food. Metabolites were identified in urine (n = 31) and plasma/serum (n = 30). Metabolites were quantified using liquid chromatography, mass spectroscopy (n = 31) and used untargeted metabolomics (n = 37). There was extensive variability in the methods used in controlled human feeding studies examining the metabolome, including dietary patterns tested, biospecimen sample collection, and metabolomic analysis techniques. To improve the comparability and reproducibility of controlled human feeding studies examining the metabolome, it is important to provide detailed information about the dietary interventions being tested, including information about included or restricted foods, food groups, and meal plans provided. Strategies to control for individual variability, such as a crossover study design, statistical adjustment methods, dietary-controlled run-in periods, or providing standardized meals or test foods throughout the study should also be considered. The protocol for this review has been registered at Open Science Framework (https://doi.org/10.17605/OSF.IO/DAHGS).

Dietary carbohydrate quality index (CQI), cardio-metabolic risk factors and insulin resistance among adults with obesity

BACKGROUND

Metabolic syndrome (MetS), as a cluster of cardiometabolic risk factors, is a global public health concern due to its increasing prevalence. Considering the previous evidence of the association between carbohydrate quality and cardiometabolic risk factors, our study was aimed to evaluate any possible association between carbohydrate quality index (CQI) and cardiometabolic risk factors among obese adults.

METHODS

In this cross-sectional study, 336 apparently healthy individuals with obesity were participated. Dietary intake was assessed by a semi-quantitative Food Frequency Questionnaire (FFQ), including 168 food items validated for the Iranian population. CQI was calculated with three components of solid carbohydrates to total carbohydrates ratio, dietary fiber intake, and dietary glycemic index (GI). Body composition was determined by bioelectrical impedance analysis (BIA). Blood pressure was measured by sphygmomanometer and enzymatic methods were used to evaluate serum lipid, glucose, and insulin concentrations.

RESULTS

Subjects in the third quartile of CQI had significantly lower systolic blood pressure (SBP) (P = 0.03) and diastolic blood pressure (DBP) (P = 0.01). Participants in the higher quartiles of CQI had more intake of energy, carbohydrates, fat, saturated fatty acid (SFA), and mono-saturated fatty acid (MUFA) (P < 0.05). Moreover, the homeostasis model assessment of insulin resistance (HOMA-IR) was decreased in the second quartile of CQI [odds ratio (OR) = 0.146, P = 0.01) after adjustment for age, body mass index (BMI), sex, physical activity, socioeconomic status (SES) and energy intake.

CONCLUSION

According to our findings, a higher quality of dietary carbohydrates, determined by CQI, could be associated with a lower risk of hypertension.

Dietary insulin index and load and cardiometabolic risk factors among people with obesity: a cross-sectional study

BACKGROUND

The hypothesis of the effect of the insulinogenic effects of diet on the development of cardiometabolic disorders has been suggested, but limited data are available for adults with obesity. This study aimed to determine the association of dietary insulin index (DII) and dietary insulin load (DIL) with cardiometabolic risk factors among Iranian adults with obesity.

METHODS

The study was conducted with a total of 347 adults aged 20-50 years in Tabriz, Iran. Usual dietary intake was assessed through a validated 147-item food frequency questionnaire (FFQ). DIL was computed using published food insulin index (FII) data. DII was calculated by dividing DIL by the total energy intake of each participant. Multinational logistic regression analysis was performed to evaluate the association between DII and DIL and cardiometabolic risk factors.

RESULTS

Mean age of participants was 40.78 ± 9.23 y, and mean body mass index (BMI) was 32.62 ± 4.80 kg/m2. Mean of DII and DIL was 73.15 ± 37.60 and 196,242 ± 100,181. Participants with higher DII had higher BMI, weight, waist circumference (WC), and blood concentrations of triglyceride (TG) and Homeostasis model assessment insulin resistance index (HOMA-IR) (P < 0.05). After taking potential confounders into account, DIL was positively associated with MetS (OR: 2.58; 95% CI: 1.03-6.46), and high blood pressure (OR: 1.61; 95% CI: 1.13-6.56). Moreover, after adjustment for potential confounders, moderate DII was associated with increased odds of MetS (OR: 1.54, 95% CI: 1.36-4.21), high TG (OR, 1.25; 95% CI, 1.17-5.02), and high blood pressure (OR: 1.88; 95% CI: 1.06-7.86).

CONCLUSION

This population-based study revealed that adults with higher DII and DIL associated with cardiometabolic risk factors and consequently, replacement of high with low DII and DIL may have reduce the risk of cardiometabolic disorders. Further studies with longitudinal design are required to confirm these findings.

The association between glycemic index and glycemic load and quality of life among overweight and obese women: a cross-sectional study

BACKGROUND

The association between different dietary approaches and quality of life (QoL) has been well-demonstrated in previous research. However, the relationship between glycemic index (GI) and glycemic load (GL) with different dimensions of QoL has not been established. Therefore, we aimed to investigate the relationship between GI and GL with QoL in overweight and obese women.

METHODS

Two hundred seventy-six overweight and obese women (body mass index (BMI) ≥ 30 kg/m2), aged 18-64 years old, were included in this cross-sectional study. The amount of dietary intake and GI and GL indexes were established using a valid and reliable Food Frequency Questionnaire (FFQ) containing 147 items. Body composition (using bioimpedance analysis), anthropometrics, and physical activity were assessed. Insulin resistance (HOMA-IR) and hs-CRP were also measured, whilst QoL was measured using the SF-36 (short-form-36), self-administered, questionnaire.

RESULT

Analyses were performed using multivariable linear regression, considering a wide range of confounding variables, such as age, physical activity, BMI, education, job, smoking, and marriage. We found a significant negative association between glycemic load and quality of life (β = -0.07, 95%CI = -0.13_ -0.01, p = 0.01). No significant associations were observed between glycemic index and quality of life (β = -0.03, 95%CI = -0.81_ 0.75, p = 0.93).

CONCLUSION

We observed a significant negative association between QoL and GL, but not GI, among overweight and obese women in Iran. Our results need to be confirmed with further well-designed and adequately powered studies that control for clinical confounders.

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.

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.

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.

Structural factors governing starch digestion and glycemic responses and how they can be modified by enzymatic approaches: A review and a guide

Starch is the most abundant glycemic carbohydrate in the human diet. Consumption of starch-rich food products that elicit high glycemic responses has been linked to the occurrence of noncommunicable diseases such as cardiovascular disease and diabetes mellitus type II. Understanding the structural features that govern starch digestibility is a prerequisite for developing strategies to mitigate any negative health implications it may have. Here, we review the aspects of the fine molecular structure that in native, gelatinized, and gelled/retrograded starch directly impact its digestibility and thus human health. We next provide an informed guidance for lowering its digestibility by using specific enzymes tailoring its molecular and three-dimensional supramolecular structure. We finally discuss in vivo studies of the glycemic responses to enzymatically modified starches and relevant food applications. Overall, structure-digestibility relationships provide opportunities for targeted modification of starch during food production and improving the nutritional profile of starchy foods.

Associations of dietary glycemic index and load during pregnancy with blood pressure, placental hemodynamic parameters and the risk of gestational hypertensive disorders

Purpose

The aim of this study was to examine the associations of dietary glycemic index and load with gestational blood pressure, placental hemodynamic parameters and the risk of gestational hypertensive disorders.

Methods

In a population-based cohort among 3378 pregnant Dutch women, dietary glycemic index and load were assessed from food frequency questionnaires at median 13.4 (95% range 9.9–22.9) weeks gestation. Blood pressure was measured in early-, mid- and late-pregnancy. Placental hemodynamic parameters were measured in mid- and late-pregnancy by ultrasound. Data on gestational hypertensive disorders was acquired from medical records.

Results

Mean dietary glycemic index (SD) was 58 (3) and mean dietary glycemic load (SD) was 155 (47). Dietary glycemic index was not associated with blood pressure, placental hemodynamic parameters and the risk of gestational hypertensive disorders. Higher dietary glycemic load SDS was associated with a higher diastolic blood pressure in early-pregnancy, remaining after adjustment for socio-demographic and lifestyle factors ((0.98 (95% CI 0.35–1.61) mmHg per SDS increase in glycemic load). No other associations of glycemic load with blood pressure or placental hemodynamic parameters and the risk of gestational hypertensive disorders were present. No significant associations of dietary glycemic index and load quartiles with longitudinal blood pressure patterns from early to late-pregnancy were present.

Conclusion

Within this low-risk pregnant population, we did not find consistent associations of dietary glycemic index and load with blood pressure, placental hemodynamic parameters and the risk of gestational hypertensive disorders. Further studies need to assess whether the effects on gestational hemodynamic adaptations are more pronounced among high-risk women with an impaired glucose metabolism.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-021-02670-5.

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.

Hiding unhealthy heart outcomes in a low-fat diet trial: the Women's Health Initiative Randomized Controlled Dietary Modification Trial finds that postmenopausal women with established coronary heart disease were at increased risk of an adverse outcome if they consumed a low-fat 'heart-healthy' diet

The Women's Health Initiative Randomized Controlled Dietary Modification Trial (WHIRCDMT) was designed to test whether the US Department of Agriculture's 1977 Dietary Guidelines for Americans protects against coronary heart disease (CHD) and other chronic diseases. The only significant finding in the original 2006 WHIRCDMT publication was that postmenopausal women with CHD randomised to a low-fat 'heart-healthy' diet in 1993 were at 26% greater risk of developing additional CHD events compared with women with CHD eating the control diet. A 2017 WHIRCDMT publication includes data for an additional 5 years of follow-up. It finds that CHD risk in this subgroup of postmenopausal women had increased further to 47%-61%. The authors present three post-hoc rationalisations to explain why this finding is 'inadmissible': (1) only women in this subgroup were less likely to adhere to the prescribed dietary intervention; (2) their failure to follow the intervention diet increased their CHD risk; and (3) only these women were more likely to not have received cholesterol-lowering drugs. These rationalisations appear spurious. Rather these findings are better explained as a direct consequence of postmenopausal women with features of insulin resistance (IR) eating a low-fat high-carbohydrate diet for 13 years. All the worst clinical features of IR, including type 2 diabetes mellitus (T2DM) in some, can be 'reversed' by the prescription of a high-fat low-carbohydrate diet. The Women's Health Study has recently reported that T2DM (10.71-fold increased risk) and other markers of IR including metabolic syndrome (6.09-fold increased risk) were the most powerful predictors of future CHD development in women; blood low-density lipoprotein-cholesterol concentration was a poor predictor (1.38-fold increased risk). These studies challenge the prescription of the low-fat high-carbohydrate heart-healthy diet, at least in postmenopausal women with IR, especially T2DM. According to the medical principle of 'first do no harm', this practice is now shown to be not evidence-based, making it scientifically unjustifiable, perhaps unethical.

Starchy vegetable intake in the first trimester is associated with a higher risk of gestational diabetes mellitus: a prospective population-based study

OBJECTIVE

The purpose of this study was to evaluate the association between starchy vegetable consumption and subgroup consumption in the first trimester and the risk of gestational diabetes mellitus (GDM).

METHODS

A prospective study (n = 1444) was conducted in China. Dietary information was assessed by 24-hour dietary recalls for three days and then we calculated the consumption of total starchy vegetable and its subgroups, including (1) potato and (2) other starchy vegetable (pumpkin, lotus root, yam, taro, water chestnut, pea, and cowpea). GDM was diagnosed according to the results of 75-g two-hour oral glucose tolerance test (OGTT) at 24-28 weeks of gestation. A modified log-binomial regression was used to estimate RRs and 95% CIs of GDM risk.

RESULTS

Among the 1444 participants in our study, 520 were diagnosed with GDM. The adjusted RRs (95% CIs) for GDM from the lowest to the highest quartiles of total starchy vegetable consumption were 1.00 (reference), 1.29 (1.06, 1.57), 1.13 (0.93, 1.40), and 1.26 (1.02, 1.56), respectively; p for trend = .032. For potato, the RR of GDM risk was 1.32 for the highest potato intake quartile compared with the lowest quartile (95% CI 1.07-1.64, p for trend = .003). In addition, we did not observe an association between other starchy vegetable intakes and GDM risk.

CONCLUSIONS

A higher consumption of total starchy vegetables and potatoes in the first trimester is associated with a greater risk of GDM.

Relationship between dietary carbohydrate quality index and metabolic syndrome among type 2 diabetes mellitus subjects: a case-control study from Ghana

BACKGROUND

Dietary carbohydrate quality may play an important role in disease development. We evaluated the association between carbohydrate quality index (CQI) and the odds of metabolic syndrome (MetS) in type 2 diabetes mellitus (T2DM) subjects in Ghana.

METHODS

In this case-control study, we analyzed data using 124 T2DM subjects. We obtained dietary information using 2-day 24-h dietary recalls. We calculated CQI from dietary fiber, glycemic index, whole grains/total grains ratio, and solid carbohydrates/total carbohydrates ratio. Serum lipid profiles were measured after an overnight fast of 8-12 h.

RESULTS

Upon adjustments for the effects of covariates, the CQI showed a positive association with high-density lipoprotein cholesterol concentration (beta coefficient (β) = 0.24; standard error (SE) = 0.20; P for trend = 0.01), and an inverse relationship with waist circumference (β = - 17.29; SE = 4.00; P for trend < 0.001), systolic blood pressure (β = - 15.74; SE = 4.69; P for trend < 0.001), diastolic blood pressure (β = - 7.23; SE = 2.97; P for trend = 0.02), and triglyceride concentrations (β = - 0.43; SE = 0.11; P for trend < 0.001). Overall, the CQI had an inverse relationship with the odds of MetS (Odds ratio _{tertile 3 vs.1} 0.05; 95% Confidence interval: 0.01-0.23; p-trend < 0.001). Also, a positive correlation was found between the CQI and fiber, but the CQI showed a negative relationship with dietary glycemic index.

CONCLUSIONS

The present results suggest an inverse association between the CQI of a diet and the odds of MetS. The CQI approach of dietary recommendation may be a useful strategy for dietary carbohydrate selection for the prevention of MetS.

Low-carbohydrate diets and cardiometabolic health: the importance of carbohydrate quality over quantity

Carbohydrates are increasingly being implicated in the epidemics of obesity, diabetes, and their downstream cardiometabolic diseases. The "carbohydrate-insulin model" has been proposed to explain this role of carbohydrates. It posits that a high intake of carbohydrate induces endocrine deregulation marked by hyperinsulinemia, leading to energy partitioning with increased storage of energy in adipose tissue resulting in adaptive increases in food intake and decreases in energy expenditure. Whether all carbohydrate foods under real-world feeding conditions directly contribute to weight gain and its complications or whether this model can explain these clinical phenomena requires close inspection. The aim of this review is to assess the evidence for the role of carbohydrate quantity vs quality in cardiometabolic health. Although the clinical investigations of the "carbohydrate-insulin model" have shown the requisite decreases in insulin secretion and increases in fat oxidation, there has been a failure to achieve the expected fat loss under low-carbohydrate feeding. Systematic reviews with pairwise and network meta-analyses of the best available evidence have failed to show the superiority of low-carbohydrate diets on long-term clinical weight loss outcomes or that all sources of carbohydrate behave equally. High-carbohydrate diets that emphasize foods containing important nutrients and substances, including high-quality carbohydrate such as whole grains (especially oats and barley), pulses, or fruit; low glycemic index and load; or high fiber (especially viscous fiber sources) decrease intermediate cardiometabolic risk factors in randomized trials and are associated with weight loss and decreased incidence of diabetes, cardiovascular disease, and cardiovascular mortality in prospective cohort studies. The evidence for sugars as a marker of carbohydrate quality appears to be highly dependent on energy control (comparator) and food source (matrix), with sugar-sweetened beverages providing excess energy showing evidence of harm, and with high-quality carbohydrate food sources containing sugars such as fruit, 100% fruit juice, yogurt, and breakfast cereals showing evidence of benefit in energy-matched substitutions for refined starches (low-quality carbohydrate food sources). These data reflect the current shift in dietary guidance that allows for flexibility in the proportion of macronutrients (including carbohydrates) in the diet, with a focus on quality over quantity and dietary patterns over single nutrients.

Determining the glycaemic responses of foods: conventional and emerging approaches

A low-glycaemic diet is crucial for those with diabetes and cardiovascular diseases. Information on the glycaemic index (GI) of different ingredients can help in designing novel food products for such target groups. This is because of the intricate dependency of material source, composition, food structure and processing conditions, among other factors, on the glycaemic responses. Different approaches have been used to predict the GI of foods, and certain discrepancies exist because of factors such as inter-individual variation among human subjects. Besides other aspects, it is important to understand the mechanism of food digestion because an approach to predict GI must essentially mimic the complex processes in the human gastrointestinal tract. The focus of this work is to review the advances in various approaches for predicting the glycaemic responses to foods. This has been carried out by detailing conventional approaches, their merits and limitations, and the need to focus on emerging approaches. Given that no single approach can be generalised to all applications, the review emphasises the scope of deriving insights for improvements in methodologies. Reviewing the conventional and emerging approaches for the determination of GI in foods, this detailed work is intended to serve as a state-of-the-art resource for nutritionists who work on developing low-GI foods.

Effects of Dietary Glycemic Index and Glycemic Load on Cardiometabolic and Reproductive Profiles in Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Women with polycystic ovary syndrome (PCOS) exhibit cardiometabolic (e.g., insulin resistance) and associated reproductive disruptions. Lifestyle modification (e.g., diet) is recommended as the first-line therapy to manage PCOS; however, a favorable dietary regimen remains unclear beyond energy restriction. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to summarize evidence on impacts of dietary glycemic index (GI) or glycemic load (GL) on cardiometabolic and reproductive profiles to update the International Evidence-based Guideline for the Assessment and Management of PCOS. Databases of MEDLINE, Cochrane, Web of Science, and Scopus were searched through 30 October 2019, and confirmed on 25 March 2020, to identify RCTs (≥8 wk) comparing the effects of diets with lower (LGI/LGL) and higher (HGI/HGL) GI/GL on glucoregulatory outcomes, lipid profile, anthropometrics, and androgen status in PCOS. The primary outcome was HOMA-IR. Data were pooled by random-effects models and expressed as weighted mean differences and 95% CIs. The risk of bias was assessed by the Cochrane tool. Ten RCTs (n = 403) were eligible. Eight evaluated LGI and 2 LGL diets. LGI diets decreased HOMA-IR (-0.78; -1.20, -0.37; I2 = 86.6%), fasting insulin (-2.39; -4.78, 0.00 μIU/mL; I2 = 76.8%), total cholesterol (-11.13; -18.23, -4.04 mg/dL; I2 = 0.0%), LDL cholesterol (-6.27; -12.01, -0.53 mg/dL; I2 = 0.0%), triglycerides (-14.85; -28.75, -0.95 mg/dL; I2 = 31.0%), waist circumference (-2.81; -4.40, -1.23 cm; I2 = 53.9%), and total testosterone (-0.21; -0.32, -0.09 nmol/L; I2 = 8.6%) compared with HGI diets (all: P ≤ 0.05) without affecting fasting glucose, HDL cholesterol, weight, or free androgen index (all: P ≥ 0.07). Some results were contradictory and only described narratively for 2 RCTs that evaluated LGL diets, since inclusion in meta-analyses was not possible. LGI diets improved glucoregulatory outcomes (HOMA-IR, insulin), lipid profiles, abdominal adiposity, and androgen status, conceivably supporting their inclusion for dietary management of PCOS. Further RCTs should confirm these observations and address whether LGI diets improve more patient-pressing complications, including ovulatory cyclicity, infertility, and cardiovascular disease risk in this high-risk population. This review was registered at www.crd.york.ac.uk/PROSPERO as CRD42020175300.

Efficacy of different dietary patterns on lowering of blood pressure level: an umbrella review

BACKGROUND

Many systematic reviews and meta-analyses have assessed the efficacy of dietary patterns on blood pressure (BP) lowering but their findings are largely conflicting.

OBJECTIVE

This umbrella review aims to provide an update on the available evidence for the efficacy of different dietary patterns on BP lowering.

METHODS

PubMed and Scopus databases were searched to identify relevant studies through to June 2020. Systematic reviews with meta-analyses of randomized controlled trials (RCTs) were eligible if they measured the effect of dietary patterns on systolic (SBP) and/or diastolic blood pressure (DBP) levels. The methodological quality of included systematic reviews was assessed by A Measurement Tool to Assess Systematic Review version 2. The efficacy of each dietary pattern was summarized qualitatively. The confidence of the effect estimates for each dietary pattern was graded using the NutriGrade scoring system.

RESULTS

Fifty systematic reviews and meta-analyses of RCTs were eligible for review. Twelve dietary patterns namely the Dietary Approaches to Stop Hypertension (DASH), Mediterranean, Nordic, vegetarian, low-salt, low-carbohydrate, low-fat, high-protein, low glycemic index, portfolio, pulse, and Paleolithic diets were included in this umbrella review. Among these dietary patterns, the DASH diet was associated with the greatest overall reduction in BP with unstandardized mean differences ranging from -3.20 to -7.62 mmHg for SBP and from -2.50 to -4.22 mmHg for DBP. Adherence to Nordic, portfolio, and low-salt diets also significantly decreased SBP and DBP levels. In contrast, evidence for the efficacy of BP lowering using the Mediterranean, vegetarian, Paleolithic, low-carbohydrate, low glycemic index, high-protein, and low-fat diets was inconsistent.

CONCLUSION

Adherence to the DASH, Nordic, and portfolio diets effectively reduced BP. Low-salt diets significantly decreased BP levels in normotensive Afro-Caribbean people and in hypertensive patients of all ethnic origins. This review was registered at PROSPERO as CRD42018104733.

Dietary glycemic index, glycemic load, and chronic disease: an umbrella review of meta-analyses of prospective cohort studies

We aimed to present a comprehensive review of the association of dietary glycemic index (GI) and load (GL) with the risk of chronic disease. Published meta-analyses of prospective observational studies evaluating the association of dietary GI and GL with risk of chronic disease were identified by a search in PubMed and Scopus to November, 2020. Summary relative risks (SRRs) were recalculated using random-effects models. The certainty of evidence was rated by the GRADE approach. Eighteen meta-analyses of prospective cohort studies, reporting 19 SRRs for dietary GI and 17 SRRs for dietary GL were identified. There was a positive association between dietary GI and the risk of type 2 diabetes, coronary heart disease, and colorectal, breast, and bladder cancers, as well as between dietary GL and the risk of coronary heart disease, type 2 diabetes, and stroke. With regard to cancers at other sites, there was no significant association. The certainty of evidence ranged from very low to low. Although by GRADE classification no associations were rated stronger than low, they were classified as one grade higher when the NutriGrade system was used. Further research is needed to add evidence for the relation of dietary GI and GL with cancer risk.

A Novel Promising Frontier for Human Health: The Beneficial Effects of Nutraceuticals in Cardiovascular Diseases

Cardiovascular diseases (CVDs) such as hypertension, atherosclerosis, myocardial infarction, and diabetes are a significant public health problem worldwide. Although several novel pharmacological treatments to reduce the progression of CVDs have been discovered during the last 20 years, the better way to contain the onset of CVDs remains prevention. In this regard, nutraceuticals seem to own a great potential in maintaining human health, exerting important protective cardiovascular effects. In the last years, there has been increased focus on identifying natural compounds with cardiovascular health-promoting effects and also to characterize the molecular mechanisms involved. Although many review articles have focused on the individual natural compound impact on cardiovascular diseases, the aim of this manuscript was to examine the role of the most studied nutraceuticals, such as resveratrol, cocoa, quercetin, curcumin, brassica, berberine and Spirulina platensis, on different CVDs.

Dietary Glycemic Index and Glycemic Load in Relation to Atherosclerotic Stenosis of Carotid and Cardiovascular Risk Factors in Ischemic Stroke Patients

Aim: Glycemic index (GI) and glycemic load (GL) influence postprandi al glucose concentrations and insulin responses. This study aims to ascertain the connection between GI, GL, and carotid atherosclerotic stenosis and cardiovascular disease (CVD) risk factors.

Methods: A total of 669 patients with ischemic stroke within 7 days were enrolled. GI and GL were assessed with a validated food frequency questionnaire from patients. Computed tomography angiography (CTA) was used for the evaluation of carotid atherosclerotic stenosis. Traditional risk factors such as total cholesterol, triglycerides, LDL-C, HDL-C, C-reactive protein, homocysteine, neutrophil to lymphocyte ratio (NLR), fasting plasma glucose, and hemoglobin A1c were measured. GI/GL and its association with CVD risk factors and carotid stenosis were explored with Spearman analysis and multivariable logistic regression, respectively.

Results: The prevalence of carotid stenosis was 63.2% of all 669 participants. The mean value of GI/GL was 49.3/137. Spearman test did not detect significant relationships between GI/GL and CVD risk factors. In multivariable regression models, GI (4^th vs. 1^st quartile, OR = 2.11; 95% CI, 1.30–3.42) and GL (4^th vs. 1^st quartile, OR = 1.82; 95% CI, 1.12–2.96) were observed a significant association with carotid stenosis after adjustment for major confounding factors. The association between GL and carotid stenosis became more pronounced among yo ungers (4^th vs. 1^st quartile, OR = 2.42; 95% CI, 1.13–4.76) and women (4^th vs. 1^st quartile, OR = 3.81; 95% CI, 1.45–5.05).

Conclusion: Higher GI and GL were positively associated with a higher degree of carotid stenosis in these Chinese cerebral infarction patients, especially in younger patients and women.

Effects of Popular Diets on Anthropometric and Cardiometabolic Parameters: An Umbrella Review of Meta-Analyses of Randomized Controlled Trials

The prevalence of overweight, obesity, and their related complications is increasing worldwide. The purpose of this umbrella review was to summarize and critically evaluate the effects of different diets on anthropometric parameters and cardiometabolic risk factors. Medline, Embase, Scopus, Cochrane Database of Systematic Reviews, and Web of Science, from inception to April 2019, were used as data sources to select meta-analyses of randomized controlled trials that examined the effects of different diets on anthropometric parameters and cardiometabolic risk factors. Strength and validity of the evidence were assessed through a set of predefined criteria. Eighty articles reporting 495 unique meta-analyses were examined, covering a wide range of popular diets: low-carbohydrate (n = 21 articles), high-protein (n = 8), low-fat (n = 9), paleolithic (n = 2), low-glycemic-index/load (n = 12), intermittent energy restriction (n = 6), Mediterranean (n = 11), Nordic (n = 2), vegetarian (n = 9), Dietary Approaches to Stop Hypertension (DASH) (n = 6), and portfolio dietary pattern (n = 1). Great variability in terms of definition of the intervention and control diets was observed. The methodological quality of most articles (n = 65; 81%), evaluated using the "A MeaSurement Tool to Assess systematic Reviews-2" questionnaire, was low or critically low. The strength of evidence was generally weak. The most consistent evidence was reported for the Mediterranean diet, with suggestive evidence of an improvement in weight, BMI, total cholesterol, glucose, and blood pressure. Suggestive evidence of an improvement in weight and blood pressure was also reported for the DASH diet. Low-carbohydrate, high-protein, low-fat, and low-glycemic-index/load diets showed suggestive and/or weak evidence of a reduction in weight and BMI, but contrasting evidence for lipid, glycemic, and blood pressure parameters, suggesting potential risks of unfavorable effects. Evidence for paleolithic, intermittent energy restriction, Nordic, vegetarian, and portfolio dietary patterns was graded as weak. Among all the diets evaluated, the Mediterranean diet had the strongest and most consistent evidence of a beneficial effect on both anthropometric parameters and cardiometabolic risk factors. This review protocol was registered at www.crd.york.ac.uk/PROSPERO/ as CRD42019126103.

Palatable Noodles as a Functional Staple Food Made Exclusively from Yellow Peas Suppressed Rapid Postprandial Glucose Increase

Legumes are low-carbohydrate food and are abundant in dietary fiber. In order to provide a functional staple food that does not cause a rapid increase in postprandial blood glucose levels, four kinds of legumes were focused on as ingredients. Noodles made from dehulled yellow pea, unshelled yellow pea, chickpea, and lentil were prepared and evaluated as functional staple foods for controlling blood glucose via an in vitro digestion method. We also measured breaking stress and breaking strain using a creep meter, as well as sensory tests on a 9-point hedonic scale. The noodles made from yellow pea had high values for both breaking stress and breaking strain, and was highly regarded in the sensory tests. Therefore, the noodles made from yellow pea on postprandial glucose and insulin response were measured in a randomized double-blind study (n = 12). The results show that noodles made from yellow pea have a low glycemic index (50.4), and have potential as a functional staple food.

Managing Cardiovascular Risk Factors without Medications: What is the Evidence?

In this era of potent medications and interventional cardiovascular (CV) procedures, the importance of beginning with and including Therapeutic Lifestyle Changes (TLC) is frequently forgotten. A major goal of this review article is to show and emphasize that modification of CV risk with nonmedication approaches makes an essential contribution to CV risk reduction. Available information on TLC and modifiable CV risk factors was reviewed and assessed. Modifiable major CV risk factors include diabetes mellitus, hypertension, hyperlipidemia, tobacco abuse, obesity, stress, and a sedentary lifestyle. Age as a major CV risk factor is, of course, not susceptible to modification. A contribution to the control of CV risk factors can occur without the start of medications and there is proof of benefit for beginning with a non-pharmacological approach. TLC can benefit all of the major modifiable CV risk factors and there is good evidence for the additional benefit of supervised and group TLC. TLC includes physical activity, diet, and smoking cessation. Evidence for the benefits of TLC in reducing CV disease events is well established. However, medications must be added in those patients with higher CV risk to obtain maximum cholesterol reduction (lower is better for the low-density lipoprotein cholesterol) and good blood pressure control. The benefit of TLC is frequently forgotten in this era of potent medications and invasive procedures. The benefits of diet and physical activity are emphasized with supporting data. Many motivated patients can prolong their lives significantly by dedication to TLC. Therapeutic Lifestyle Change (TLC) especially encompasses increased physical activity, a healthy diet, and smoking cessation. There is extensive proof for the benefit of TLC in contributing to cardiovascular (CV) disease prevention. CV diseases have strong metabolic and inflammatory components, both of which can be improved by TLC.

The association between glycemic index, glycemic load, and metabolic syndrome: a systematic review and dose-response meta-analysis of observational studies

PURPOSE

The association of glycemic index (GI) and glycemic load (GL) with metabolic syndrome (MetS) is controversial. Therefore, we conducted this first systematic review and dose-response meta-analysis of observational studies to quantify these associations.

METHODS

We searched PubMed, EMBASE, Web of Science, and the Cochrane Library for relevant studies up to 1 April 2019. Summary odds ratios (OR) and 95% confidence intervals (CI) were calculated by a random-effects model. This study was registered with PROSPERO (CRD42019131788).

RESULTS

We included eight high-quality (n = 5) or medium-quality (n = 3) cross-sectional studies in the final meta-analysis, comprising 6058 MetS events and 28,998 participants. The summary ORs of MetS for the highest versus lowest categories were 1.23 (95% CI 1.10-1.38, I² = 0, tau² = 0, n = 5) for dietary GI, 1.06 (95% CI 0.89-1.25, I² = 36.2%, tau² = 0.0151, n = 6) for dietary GL. The summary OR was 1.12 (95% CI 1.00-1.26, I² = 0, tau² = 0, n = 3) per 5 GI units, 0.96 (95% CI 0.83-1.10, I² = 33.4%, tau² = 0.0059, n = 2) per 20 GL units.

CONCLUSIONS

Dietary GI was positively associated with the prevalence of MetS. However, no significant association was found between dietary GL and the prevalence of MetS. Further studies with prospective design are needed to establish potential causal relationship between dietary GI and the MetS.

The association of glycemic index and glycemic load with elevated blood pressure in Iranian women

Introduction: Dietary intake is a risk factor related to elevated blood pressure (EBP). Few studies have investigated an association of dietary glycemic index (GI) and glycemic load (GL) with the EBP. The aim of the current study was to examine the association of dietary GI and GL with the EBP among a group of healthy women. Methods: This population-based cross-sectional study was conducted on 306 healthy women. Dietary GI and GL were measured using a validated semi-quantitative food frequency questionnaire (FFQ). Blood pressure (BP) was measured twice by a mercury sphygmomanometer from the right arm. Anthropometric measurements were also assessed according to the standard protocols. Results: Before controlling for potential confounders, no significant association was seen between dietary GI/GL and SBP/DBP. Also after controlling for potential confounders, the associations did not change between dietary GI and SBP (odds ratio [OR]: 0.96; 95% CI: 0.42-2.17, P = 0.87), between GI and DBP (OR: 0.72; 95% CI: 0.35-1.45, P = 0.37), as well as between GL and SBP (OR: 1.04; 95% CI: 0.43-2.49, P = 1.00) and between GL and DBP (OR: 1.20; 95% CI: 0.56-2.00, P = 0.61). In a stratified analysis by obesity and overweight, differences between tertiles of GI were not significant (OR: 0.75; 95% CI: 0.42-1.31, P = 0.31), even after adjustment for the potential confounders (OR: 1.54; 95% CI: 0.70-3.40, P = 0.26). Conclusion: This study did not show a significant association between dietary GI/GL and the risk of high SBP/DBP. In addition, no significant association was found between dietary GI/GL and odds of overweight or obesity in adult women.

Substantial and Sustained Improvements in Blood Pressure, Weight and Lipid Profiles from a Carbohydrate Restricted Diet: An Observational Study of Insulin Resistant Patients in Primary Care

Hypertension is the second biggest known global risk factor for disease after poor diet; perhaps lifestyle interventions are underutilized? In a previous small pilot study, it was found that a low carbohydrate diet was associated with significant improvements in blood pressure, weight, 'deprescribing' of medications and lipid profiles. We were interested to investigate if these results would be replicated in a larger study based in 'real world' GP practice. 154 patients with type 2 diabetes or impaired glucose tolerance were recruited into an observational cohort study in primary care. The effects of a low carbohydrate diet sustained for an average of two years (interquartile range 10-32 months) on cardiovascular risk factors were examined. Results demonstrate significant and substantial reductions in blood pressure (mean reduction of systolic BP 10.9 mmHg (interquartile range 0-22 mmHg) (p < 0.0001), mean reduction in diastolic BP 6.3 mmHg (interquartile range 0-12.8 mmHg) (p < 0.0001) and mean weight reduction of 9.5 Kg (interquartile range 5-13 Kg) (p < 0.0001) together with marked improvement in lipid profiles. This occurred despite a 20% reduction in anti-hypertensive medications. This novel and potentially highly effective dietary modification, done very cheaply alongside routine care, offers hope that should be tested in a large prospective trial.

Dietary fibre and cardiovascular health: a review of current evidence and policy

Dietary fibre comprises many different, mainly plant-based, compounds that are not fully digested in the human gut. Insoluble fibres include cellulose, hemi-celluloses and lignin and soluble fibres include pectins, β-glucan and hydro-colloids. In the UK, the daily recommended amount has increased to 30 g but only 13 % of men and 4 % of women meet this recommendation. Currently the mean intake for adults is 21 g for men and 17 g for women. There is a wealth of epidemiological evidence based on systematic reviews of trials and cohorts to support the higher fibre recommendation. This includes evidence of reductions in the risk for CVD (both heart disease and stroke) and lower risk of type 2 diabetes, lower blood pressure, lower LDL-cholesterol, as well as some cancers. Beneficial effects of fibre operate via a diverse range of mechanisms throughout the digestive system including the mouth, stomach and small and large intestine; some of which are still not completely understood. The updated recommendation for fibre is a long way from a typical British diet and requires several daily portions of fruit and vegetables and wholegrain foods. Improving dietary fibre intakes will require a variety of actions and policies from stakeholders; however, there is currently more of a focus on reducing sugar than increasing fibre. In order to increase the number of adults meeting the fibre recommendation, social marketing and labelling of high-fibre foods are warranted as well as reformulation and wider availability of wholegrain versions of popular foods.

Quantity, Quality, and Timing of Carbohydrate Intake and Blood Pressure

PURPOSE OF REVIEW

This review discusses recent evidence on the association of dietary carbohydrates (quantity, quality, and timing of intake) with hypertension (HTN) risk and out-of-clinic blood pressure (BP) measures.

RECENT FINDINGS

Studies on carbohydrate quantity are inconclusive, but low carbohydrate diets may be associated with lower BP. Plant-based carbohydrate-containing foods such as fruits, vegetables, and whole grains may lower HTN risk and 24-h BP. Excessive sugar intakes from sugar-sweetened beverages are associated with higher BP levels and HTN risk, with evidence of a dose-response relationship. Preliminary data suggest that timing of carbohydrate intake may influence HTN risk and 24-h BP. The role of carbohydrate nutrition in HTN's etiology warrants further investigation. Additional studies are needed to investigate the influence of dietary carbohydrates on HTN risk and the circadian pattern of BP, evaluate potential sex and racial/ethnic differences in these associations, and elucidate underlying mechanisms.

Differences in endosperm cell wall integrity in wheat (Triticum aestivum L.) milling fractions impact on the way starch responds to gelatinization and pasting treatments and its subsequent enzymatic in vitro digestibility

Intact wheat endosperm cell walls reduce intracellular starch swelling and retard its in vitro digestion by acting as physical barriers to amylolytic enzymes.

Changes in Plasma Metabolite Concentrations after a Low-Glycemic Index Diet Intervention

SCOPE

To examine whether a low-glycemic index (LGI) diet improves a set of plasma metabolites related to different metabolic diseases, and comparison to a high-glycemic index (HGI) diet and a low-fat (LF) diet.

METHODS AND RESULTS

A parallel, randomized trial with three intervention diets: an LGI diet, an HGI diet, and an LF diet. A total of 122 adult overweight and obese subjects were enrolled in the study for 6 months. Blood samples were collected at baseline and at the end of the intervention. The plasma metabolomic profile of 102 subjects was analyzed using three different approaches: GC/quadrupole-TOF, LC/quadrupole-TOF, and nuclear magnetic resonance. Both univariate and multivariate analysis were performed. Serine levels were significantly higher following the LGI diet compared to both the HGI and LF diets (q = 0.002), whereas leucine (q = 0.015) and valine (q = 0.024) were lower in the LGI diet compared to the LF diet. A set of two sphingomyelins, two lysophosphatidylcholines, and six phosphatidylcholines were significantly modulated after the LGI diet compared to the HGI and LF diets (q < 0.05). Significant correlations between changes in plasma amino acids and lipid species with changes in body weight, glucose, insulin, and some inflammatory markers are also reported.

CONCLUSION

These results suggest that an LGI diet modulates certain circulating amino acids and lipid levels. These findings may explain the health benefits attributed to LGI diets in metabolic diseases such as type 2 diabetes.

Polydopamine particles as nontoxic, blood compatible, antioxidant and drug delivery materials

Herein, the potential biomedical application of poly(3,4-dihyroxyphenyl)ethylamine, (poly(dopamine)-p(DA)) particles is reported. P(DA) particles with the size about 100 nm, 18.05 m²/g specific surface area, and mesoporous structure (7.19 nm pore width) were prepared and shown to be chemically modifiable using chlorosulfonic acid (CSA) and 3-CHloro-2 hydroxypropyl) trimethylammonium chloride solution (CHPACl) to obtain sulfonic acid and quaternary amine group containing modified p(DA) particles, m-p(DA)-CSA and m-p(DA)-CHPACl particles, respectively. The hydrolytic degradation of p(DA) particles at different pHs, including 1, 7.4 and 11, was carried out at 37.5 °C. These degradation studies revealed that p(DA) is slightly degradable at pH 1 and pH 7.4 with weight losses of 13.01 ± 0.08% and 7.26 ± 0.23% in 11 days, respectively. At pH 11, a sustained degradation that is almost linear degradation with time was observed for up to 30 days, with a total weight loss of 21.42 ± 0.88%. Furthermore, p(DA) particles were tested for cell toxicity against COS-1 cells and found non-toxic up to 50 μg/mL with 95.6 ± 4.5% cell viability as compared to 37.5 ± 0.03% for DA molecules. The p(DA) particles and DA were also compared for their ability to inhibit α-glucosidase; both inhibited α-glucosidase inhibition activity a concentration-dependent fashion: at concentrations of 500-4000 μg/mL, p(DA) provided 8.52-27.67% inhibition while DA inhibited 42.8-67.7% over the same concentration range. Furthermore, p(DA) particles were found to be blood compatible e.g., non-hemolytic with 1.87 ± 0.97% hemolysis ratio up to 50 μg/mL concentration and with 86.7% blood clotting index. Interestingly, p(DA) particle can be considered as an effective antioxidant with 33.5 ± 3.9 μg/ mL total phenol content in terms of gallic acid equivalency and 0.89 ± 0. 30 μmol/g trolox equivalent antioxidant capacity (TEAC). Finally, p(DA) particles and their modified forms, m-p(DA)-CSA, and m-p(DA)-CHPACl, were shown to be useful as active agent/drug delivery devices by using acyclovir as a model drug that can be readily loaded into particles and released at longer times at higher amounts for the modified p(DA) particles at physiological conditions.

Claimed effects, outcome variables and methods of measurement for health claims proposed under European Community Regulation 1924/2006 in the area of blood glucose and insulin concentrations

Most requests for authorization to bear health claims under Articles 13(5) and 14 related to blood glucose and insulin concentration/regulation presented to the European Food Safety Authority (EFSA) receive a negative opinion. Reasons for such decisions are mainly ascribable to poor substantiation of the claimed effects. In this scenario, a project was carried out aiming at critically analysing the outcome variables (OVs) and methods of measurement (MMs) to be used to substantiate health claims, with the final purpose to improve the quality of applications provided by stakeholders to EFSA. This manuscript provides a position statement of the experts involved in the project, reporting the results of an investigation aimed to collect, collate and critically analyse the information relevant to claimed effects (CEs), OVs and MMs related to blood glucose and insulin levels and homoeostasis compliant with Regulation 1924/2006. The critical analysis of OVs and MMs was performed with the aid of the pertinent scientific literature and was aimed at defining their appropriateness (alone or in combination with others) to support a specific CE. The results can be used to properly select OVs and MMs in a randomized controlled trial, for an effective substantiation of the claims, using the reference method(s) whenever available. Moreover, results can help EFSA in updating the guidance for the scientific requirements of health claims.

Protection from chronic stress- and depressive symptom-induced vascular endothelial dysfunction in female rats is abolished by preexisting metabolic disease

While it is known that chronic stress and clinical depression are powerful predictors of poor cardiovascular outcomes, recent clinical evidence has identified correlations between the development of metabolic disease and depressive symptoms, creating a combined condition of severely elevated cardiovascular disease risk. In this study, we used the obese Zucker rat (OZRs) and the unpredictable chronic mild stress (UCMS) model to determine the impact of preexisting metabolic disease on the relationship between chronic stress/depressive symptoms and vascular function. Additionally, we determined the impact of metabolic syndrome on sex-based protection from chronic stress/depressive effects on vascular function in female lean Zucker rats (LZRs). In general, vasodilator reactivity was attenuated under control conditions in OZRs compared with LZRs. Although still impaired, conduit arterial and resistance arteriolar dilator reactivity under control conditions in female OZRs was superior to that in male or ovariectomized (OVX) female OZRs, largely because of better maintenance of vascular nitric oxide and prostacyclin levels. However, imposition of metabolic syndrome in combination with UCMS in OZRs further impaired dilator reactivity in both vessel subtypes to a similarly severe extent and abolished any protective effect in female rats compared with male or OVX female rats. The loss of vascular protection in female OZRs with UCMS was reflected in vasodilator metabolite levels, which closely matched those in male and OVX female OZRs subjected to UCMS. These results suggest that presentation of metabolic disease in combination with depressive symptoms can overwhelm the vasoprotection identified in female rats and, thereby, may reflect a severe impairment to normal endothelial function. NEW & NOTEWORTHY This study addresses the protection from chronic stress- and depression-induced vascular dysfunction identified in female compared with male or ovariectomized female rats. We determined the impact of preexisting metabolic disease, a frequent comorbidity of clinical depression in humans, on that vascular protection. With preexisting metabolic syndrome, female rats lost all protection from chronic stress/depressive symptoms and became phenotypically similar to male and ovariectomized female rats, with comparably poor vasoactive dilator metabolite profiles.