Effects of rye and whole wheat versus refined cereal foods on metabolic risk factors: a randomised controlled two-centre intervention study

Effect of Barley and Oat Consumption on Immune System, Inflammation and Gut Microbiota: A Systematic Review of Randomized Controlled Trials

PURPOSE OF REVIEW

The aim of this systematic review was to investigate the effects of whole grain Avena sativa and Hordeum vulgare L., or their isolated fractions, on immune and inflammatory functions, as well as their influence on gut microbiota. A structured literature search was undertaken in line with PRISMA guidelines. Randomized controlled trials (RCTs) that investigated the effects of oats or barley consumption in adults and reported ≥ 1 of the following: C-reactive protein (CRP), tumor necrosis factor (TNF-α), interleukin-6 (IL-6), IL-2, IL-8, IL-18, lipopolysacharide binding protein (LBP) or gut microbiota-related outcomes, were included.

RECENT FINDINGS

A total of 16 RCTs were included, among which 6 studies recruited metabolically at-risk population, including individuals with overweight and obesity, metabolic syndrome or hypercholesterolemia. Additionally, 3 trials involved young healthy population, 5 trials targeted older individuals (aged over 50 years), and 2 studies encompassed populations with other disease states. A total of 1091 individuals were included in the evaluation of short-term (up to 14 days) and long-term (beyond 14 days, up to 90 days) supplementation with oats or barley-based products. 9 studies measured inflammatory biomarkers and 5 of them reported significant reductions, specifically in long-term studies. Notably, no evidence of anti-inflammatory benefits was found in healthy individuals, whereas studies involving metabolically at-risk populations showed promising reductions in inflammation. 13 studies measured the impact on gut microbiota, and collectively suggest that oats and barley food products can influence the composition of gut microbiota, associated in some cases with metabolic improvements. Oats and barley consumption may confer anti-inflammatory effects in metabolically at-risk populations and influence gut microbiota outcomes. However, no anti-inflammatory benefits were observed in healthy individuals. Results from this systematic review suggests caution in interpreting findings due to limited trials and variations in interventions and health conditions.

Effects of whole grains on glycemic control: a systematic review and dose-response meta-analysis of prospective cohort studies and randomized controlled trials

PURPOSE

Whole grains have recently been promoted as beneficial to diabetes prevention. However, the evidence for the glycemic benefits of whole grains seems to conflict between the cohort studies and randomized control trials (RCTs). To fill the research gap, we conducted a meta-analysis to determine the effects of whole grains on diabetes prevention and to inform recommendations.

METHODS

We searched PubMed, Clarivate Web of Science, and Cochrane Library until March 2024. We used the risk ratio (RR) of type 2 diabetes to represent the clinical outcomes for cohort studies, while the biomarkers, including fasting blood glucose and insulin, HbA1C, and HOMA-IR, were utilized to show outcomes for RCTs. Dose-response relationships between whole grain intakes and outcomes were tested with random effects meta-regression models and restricted cubic splines models. This study is registered with PROSPERO, CRD42021281639.

RESULTS

Ten prospective cohort studies and 37 RCTs were included. Cohort studies suggested a 50 g/day whole grain intake reduced the risk of type 2 diabetes (RR = 0.761, 95% CI: 0.700 to 0.828, I2 = 72.39%, P < 0.001) and indicated a monotonic inverse relationship between whole grains and type 2 diabetes rate. In RCTs, whole grains significantly reduced fasting blood glucose (Mean difference (MD) = -0.103 mmol/L, 95% CI: -0.178 to -0.028; I2 = 72.99%, P < 0.01) and had modest effects on HbA1C (MD = -0.662 mmol/mol (-0.06%), 95% CI: -1.335 to 0.010; I2 = 64.55%, P = 0.05) and HOMA-IR (MD = -0.164, 95% CI: -0.342 to 0.013; I2 = 33.38%, P = 0.07). The intake of whole grains and FBG, HbA1C, and HOMA-IR were significantly dose-dependent. The restricted spline curves remained flat up to 150 g/day and decreased afterward. Subgroup analysis showed that interventions with multiple whole-grain types were more effective than those with a single type.

CONCLUSION

Our study findings suggest that a daily intake of more than 150 g of whole grain ingredients is recommended as a population approach for diabetes prevention.

New Advances in Metabolic Syndrome, from Prevention to Treatment: The Role of Diet and Food

The definition of metabolic syndrome (MetS) has undergone several changes over the years due to the difficulty in establishing universal criteria for it. Underlying the disorders related to MetS is almost invariably a pro-inflammatory state related to altered glucose metabolism, which could lead to elevated cardiovascular risk. Indeed, the complications closely related to MetS are cardiovascular diseases (CVDs) and type 2 diabetes (T2D). It has been observed that the predisposition to metabolic syndrome is modulated by complex interactions between human microbiota, genetic factors, and diet. This review provides a summary of the last decade of literature related to three principal aspects of MetS: (i) the syndrome's definition and classification, pathophysiology, and treatment approaches; (ii) prediction and diagnosis underlying the biomarkers identified by means of advanced methodologies (NMR, LC/GC-MS, and LC, LC-MS); and (iii) the role of foods and food components in prevention and/or treatment of MetS, demonstrating a possible role of specific foods intake in the development of MetS.

Health Provider's Feedback on Physical Activity Surveillance Using Wearable Device-Smartphone Application for Adults with Metabolic Syndrome; a 12-Week Randomized Control Study

Purpose

Research on whether wearable device interventions can effectively prevent metabolic syndrome remains insufficient. This study aimed to evaluate the effect of feedback on clinical indicators in patients with metabolic syndrome on activities measured using wearable devices, such as smartphone apps.

Methods

Patients with metabolic syndrome were recruited and prescribed to live for 12 weeks using a wrist-wearable device (B.BAND, B Life Inc., Korea). A block randomization method was used to distribute participants between the intervention (n=35) and control groups (n=32). In the intervention group, an experienced study coordinator provided feedback on physical activity to individuals through telephonic counseling every other week.

Results

The mean number of steps in the control group was 8892.86 (4473.53), and those in the intervention group was 10,129.31 (4224.11). After 12 weeks, metabolic syndrome was resolved. Notably, there were statistically significant differences in the metabolic composition among the participants who completed the intervention. The mean number of metabolic disorder components per person remained at 3 in the control group, and decreased from 4 to 3 in the intervention group. Additionally, waist circumference, systolic and diastolic blood pressure, and triglyceride levels were significantly reduced, while HDL-cholesterol levels were significantly increased in the intervention group.

Conclusion

Overall, 12 weeks of telephonic counseling intervention using wearable device-based physical activity confirmation improved the damaged metabolic components of patients with metabolic syndrome. Telephonic intervention can help increase physical activity and reduce waist circumference, which is a typical clinical indicator of metabolic syndrome.

Are all fibres created equal with respect to lipid lowering? Comparing the effect of viscous dietary fibre to non-viscous fibre from cereal sources: a systematic review and meta-analysis of randomised controlled trials

Although compelling evidence from observational studies supports a positive association between consumption of cereal fibre and CVD risk reduction, randomised controlled trials (RCT) often target viscous fibre type as the prospective contributor to lipid lowering to reduce CVD risk. The objective of our study is to compare the lipids-lowering effects of viscous dietary fibre to non-viscous, cereal-type fibre in clinical studies. RCT that evaluated the effect of viscous dietary fibre compared with non-viscous, cereal fibre on LDL cholesterol and alternative lipid markers, with a duration of ≥ 3 weeks, in adults with or without hypercholesterolaemia were included. Medline, EMBASE, CINAHL and the Cochrane Central Register were searched through October 19, 2021. Data were extracted and assessed by two independent reviewers. The generic inverse variance method with random effects model was utilised to pool the data which were expressed as mean differences (MD) with 95 % CI. Eighty-nine trials met eligibility criteria (n 4755). MD for the effect of viscous dietary fibre compared with non-viscous cereal fibre were LDL cholesterol (MD = -0·26 mmol/l; 95 % CI: -0·30, -0·22 mmol/l; P < 0·01), non-HDL cholesterol (MD = -0·33 mmol/l; 95 % CI: -0·39, -0·28 mmol/l; P < 0·01) and Apo-B (MD = -0·04 g/l; 95 % CI: -0·06, -0·03 g/l; P < 0·01). Viscous dietary fibre reduces LDL cholesterol and alternative lipid markers relative to the fibre from cereal sources, hence may be a preferred type of fibre-based dietary intervention targeting CVD risk reduction.

Effects of whole grain intake on glycemic control: a meta-analysis of randomized controlled trials

Aims/Introduction

Although mounting evidence has suggested an inverse association between the intake of whole grains and glycemic control, findings from randomized controlled trials are still conflicting. The current study was carried out to evaluate the effect of medium/long‐term whole grain intake on glycemic control in metabolic syndrome and healthy populations.

Materials and Methods

A literature search was carried out to identify qualified studies up to July 2021. The effects of whole grain consumption on glycemic control were calculated using a fixed effects model. Subgroup analysis was used to study whether grouping factors were important influencing factors of heterogeneity between research results.

Results

A total of 32 randomized controlled trials with 2,060 participants were included in the analyses. Whole grain consumption showed a significant inverse regulatory effect on fasting glucose concentration, but no significant effect was found for other glycemic measures, such as fasting insulin, homeostatic model assessment for insulin resistance, glycated hemoglobin and 2‐h glucose, in the pooled analysis. Through subgroup analyses, a significant decrease in fasting glucose concentration was observed for studies with a higher whole grain dose, with participants of normal glycemia, and with mixed types of whole grain.

Conclusions

Medium‐/long‐term whole grain intake reduced the fasting glucose concentration compared with similar refined foods. Appropriate intervention dose and accurate population selection might be the key links for whole grain consumption to exert its glycemic control effect.

Thirty‐two RCTs with 2060 participants were included in analyses. The whole grain consumption showed significant inverse regulation effect on fasting glucose concentration.

The Use and Effectiveness of Selected Alternative Markers for Insulin Sensitivity and Secretion Compared with Gold Standard Markers in Dietary Intervention Studies in Individuals without Diabetes: Results of a Systematic Review

Background: The gold-standard techniques for measuring insulin sensitivity and secretion are well established. However, they may be perceived as invasive and expensive for use in dietary intervention studies. Thus, surrogate markers have been proposed as alternative markers for insulin sensitivity and secretion. This systematic review aimed to identify markers of insulin sensitivity and secretion in response to dietary intervention and assess their suitability as surrogates for the gold-standard methodology. Methods: Three databases, PubMed, Scopus, and Cochrane were searched, intervention studies and randomised controlled trials reporting data on dietary intake, a gold standard of analysis of insulin sensitivity (either euglycaemic-hyperinsulinaemic clamp or intravenous glucose tolerance test and secretion (acute insulin response to glucose), as well as surrogate markers for insulin sensitivity (either fasting insulin, area under the curve oral glucose tolerance tests and HOMA-IR) and insulin secretion (disposition index), were selected. Results: We identified thirty-five studies that were eligible for inclusion. We found insufficient evidence to predict insulin sensitivity and secretion with surrogate markers when compared to gold standards in nutritional intervention studies. Conclusions: Future research is needed to investigate if surrogate measures of insulin sensitivity and secretion can be repeatable and reproducible in the same way as gold standards.

Effects of Dietary Intervention on Inflammatory Markers in Metabolic Syndrome: A Systematic Review and Meta-Analysis

Background

Dietary interventions may modulate inflammatory indicators, but the correlations between dietary intervention and inflammatory markers in metabolic syndrome (MetS) settings remain opaque.

Objective

To evaluate the effects of dietary intervention on interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and C-reactive protein (CRP) in patients with MetS by systematic review and meta-analysis.

Methods

Databases, including PubMed, Embase, Cochrane Library, Scopus, and Google scholar, were searched from June 2011 to June 2021 for relevant available articles. Standardized mean difference (SMD) was generated as effect size by meta-analysis for continuous variants, including IL-1β, IL-6, TNF-α, and CRP levels. Then, according to study characteristics by dietary patterns of the intervention, subgroup analyses were performed.

Results

Finally, 13 studies comprising a total of 1,101 participants were included for the meta-analysis. IL-6 levels in dietary patients were significantly lower than controls (SMD = -0.30, 95% CI = -0.55, 0.04, p = 0.02, I2 = 64%). However, IL-1β, TNF-α, and CRP levels did not change significantly compared with the control group. Sensitivity analyses further yielded similar results.

Conclusions

Dietary intervention may help decrease IL-6 rather than IL-1β, TNF-α, or CRP levels in patients with MetS.

Whole Grain Consumption and Inflammatory Markers: A Systematic Literature Review of Randomized Control Trials

Whole grain foods are rich in nutrients, dietary fibre, a range of antioxidants, and phytochemicals, and may have potential to act in an anti-inflammatory manner, which could help impact chronic disease risk. This systematic literature review aimed to examine the specific effects of whole grains on selected inflammatory markers from human clinical trials in adults. As per the Preferred Reporting Items for Systematic Reviews (PRISMA) protocol, the online databases MEDLINE, Embase, Cochrane, CINAHL, and Scopus were searched from inception through to 31 August 2021. Randomized control trials (RCTs) ≥ 4 weeks in duration, reporting ≥1 of the following: C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor (TNF), were included. A total of 31 RCTs were included, of which 16 studies recruited overweight/obese individuals, 12 had pre-existing conditions, two were in a healthy population, and one study included participants with prostate cancer. Of these 31 RCTs, three included studies with two intervention arms. A total of 32 individual studies measured CRP (10/32 were significant), 18 individual studies measured IL-6 (2/18 were significant), and 13 individual studies measured TNF (5/13 were significant). Most often, the overweight/obese population and those with pre-existing conditions showed significant reductions in inflammatory markers, mainly CRP (34% of studies). Overall, consumption of whole grain foods had a significant effect in reducing at least one inflammatory marker as demonstrated in 12/31 RCTs.

The associations between whole grain and refined grain intakes and serum C-reactive protein

BACKGROUND/OBJECTIVES

Epidemiological studies suggest that whole grain intake has inverse associations with low-grade inflammation, but findings regarding refined grains are inconclusive. Our objective was to investigate whether consumption of whole or refined grains is associated with serum high sensitivity CRP (hs-CRP).

SUBJECTS/METHODS

The study included 756 generally healthy men and women aged 53-73 years from the Kuopio Ischaemic Heart Disease Risk Factory Study, examined in 1999-2001. Dietary intakes were assessed using 4-day food records. ANCOVA and linear regression were used for analyses.

RESULTS

The mean intake of whole and refined grains was 136 g/day (SD 80) and 84 g/day (SD 46), respectively. Higher whole grain intake was associated with lower hs-CRP concentration and higher refined grain intake with higher concentration after adjustment for lifestyle and dietary factors. Each 50 g/d higher whole grain intake was associated with 0.12 mg/L (95% Cl 0.02-0.21 mg/L) lower hs-CRP concentration and each 50 g/d higher refined grain intake with 0.23 mg/L (95% Cl 0.08-0.38) higher concentration. Adjustment for fibre from grains attenuated the associations especially with whole grains. There were no statistically significant interactions according to gender or BMI (P for interactions >0.065).

CONCLUSIONS

The results of this study suggest that higher intake of whole grains is associated with lower concentrations of hs-CRP and higher intake of refined grains is associated with higher concentrations. However, especially the association with whole grain intake was attenuated after adjusting for fibre intake from grains, suggesting that cereal fibre may partly explain the association.

Effects of whole grain intake on glycemic traits: A systematic review and meta-analysis of randomized controlled trials

Whole grains (WGs) may have various health benefits, including lowering blood glucose and improving insulin sensitivity. To conduct a meta-analysis of the effects of WGs compared with non-WGs on changes in fasting glucose, fasting insulin, glycated hemoglobin (HbA1c), and homeostasis model assessment of insulin resistance (HOMA-IR). A systematic literature search was performed for all published randomized controlled trials on the effects of WG intake on fasting glucose, fasting insulin, HbA1c and HOMA-IR response up to February 2021. Weighted mean differences (WMD) were calculated. Pre-specified subgroup and univariate meta-regression analyses were explored to identify the sources of heterogeneity. Sensitivity analysis and bias analysis were conducted to appraise study quality. Among 12,435 articles screened for eligibility, data were extracted from 48 articles. Meta-analysis of 4,118 participants showed that WG consumption resulted in a significant reduction in fasting glucose by -0.15 mmol/L, fasting insulin by -2.71 pmol/L, HbA1c by -0.44%, and HOMA-IR by -0.28, respectively. Compared with mixed grains, brown rice, and wheat, oats were significantly lower on marker of glycemic. Besides, multiple interventions per day consolidated effectiveness of WGs. WG consumption decreased the levels of fasting glucose, fasting insulin, HbA1c, and HOMA-IR compared with non-WG consumption.

The effects of nondigestible fermentable carbohydrates on adults with overweight or obesity: a meta-analysis of randomized controlled trials

CONTEXT

Nondigestible fermentable carbohydrates (NDFCs) can be fermented by microbiota, thereby yielding metabolites that have a beneficial role in the prevention and treatment of obesity and its complications. However, to our knowledge, no meta-analysis has been conducted to evaluate the effects of NDFCs on obesity.

OBJECTIVE

To conduct a meta-analysis of randomized controlled trials (RCTs) to summarize existing evidence on the effects of numerous NDFCs on adiposity and cardiovascular risk factors in adults with overweight or obesity with ≥2 weeks of follow-up.

DATA SOURCES

The following databases were searched: MEDLINE, Embase, and CINAHL.

DATA EXTRACTION

Seventy-seven RCTs with 4535 participants were identified for meta-analysis from the 3 databases.

DATA ANALYSIS

The findings suggest that increased intake of NDFCs is significantly effective in reducing body mass index by 0.280 kg/m2, weight by 0.501 kg, hip circumference by 0.554 cm, waist circumference by 0.649 cm, systolic blood pressure by 1.725 mmHg, total cholesterol by 0.36 mmol/L, and low-density lipoprotein by 0.385 mmol/L, with evidence of moderate-to-high quality.

CONCLUSION

Convincing evidence from meta-analyses of RCTs indicates that increased NDFC intake improves adiposity, blood lipid levels, and systolic blood pressure in people with overweight and obesity.

Analysis of the intricate effects of polyunsaturated fatty acids and polyphenols on inflammatory pathways in health and disease

Prevention and treatment of non-communicable diseases (NCDs), including cardiovascular disease, diabetes, obesity, cancer, Alzheimer's and Parkinson's disease, arthritis, non-alcoholic fatty liver disease and various infectious diseases; lately most notably COVID-19 have been in the front line of research worldwide. Although targeting different organs, these pathologies have common biochemical impairments - redox disparity and, prominently, dysregulation of the inflammatory pathways. Research data have shown that diet components like polyphenols, poly-unsaturated fatty acids (PUFAs), fibres as well as lifestyle (fasting, physical exercise) are important factors influencing signalling pathways with a significant potential to improve metabolic homeostasis and immune cells' functions. In the present manuscript we have reviewed scientific data from recent publications regarding the beneficial cellular and molecular effects induced by dietary plant products, mainly polyphenolic compounds and PUFAs, and summarize the clinical outcomes expected from these types of interventions, in a search for effective long-term approaches to improve the immune system response.

Glycemic Index and Sensory Evaluation of Whole Grain Based Multigrain Indian Breads (Rotis)

Whole grain-based foods have been shown to reduce the risk of development of metabolic syndrome. In this study, we formulated whole grain-based multigrain flour and analyzed for available carbohydrate content, glycemic index (GI), and sensory evaluation. The multigrain flour composition 1 (C1) and composition 2 (C2) were formulated using defatted soya or bengal gram as a source of protein along with millets (40∼45%) and whole cereals. The proximate composition was calculated using Indian food composition tables. The microbial load and free fatty acid contents were analyzed in flour samples that were stored for different durations. The total dietary fiber, protein, and carbohydrate contents per 100 g of C1 and C2 flours were in the range of 11∼14, 13∼15, and 60 g, respectively. The available carbohydrate content in C1 and C2 were 55.4 and 62.3 g, and the in vivo GI was 63.2 and 66.2%, respectively. The acceptability scores of C1 and C2 products were in the range of 3.38 to 3.39 on the 5 points Hedonic scale. The multigrain flours were stable for 3 months based on microbial load and rancidity. The observed GIs of the multigrain flour were much lower than that of commercial refined wheat products. Therefore, these products may be recommended to regular diet plans to help prevent and/or ameliorate metabolic syndrome in the general population.

Chronic Inflammation in the Context of Everyday Life: Dietary Changes as Mitigating Factors

The lifestyle adopted by most people in Western societies has an important impact on the propensity to metabolic disorders (e.g., diabetes, cancer, cardiovascular disease, neurodegenerative diseases). This is often accompanied by chronic low-grade inflammation, driven by the activation of various molecular pathways such as STAT3 (signal transducer and activator of transcription 3), IKK (IκB kinase), MMP9 (matrix metallopeptidase 9), MAPK (mitogen-activated protein kinases), COX2 (cyclooxigenase 2), and NF-Kβ (nuclear factor kappa-light-chain-enhancer of activated B cells). Multiple intervention studies have demonstrated that lifestyle changes can lead to reduced inflammation and improved health. This can be linked to the concept of real-life risk simulation, since humans are continuously exposed to dietary factors in small doses and complex combinations (e.g., polyphenols, fibers, polyunsaturated fatty acids, etc.). Inflammation biomarkers improve in patients who consume a certain amount of fiber per day; some even losing weight. Fasting in combination with calorie restriction modulates molecular mechanisms such as m-TOR, FOXO, NRF2, AMPK, and sirtuins, ultimately leads to significantly reduced inflammatory marker levels, as well as improved metabolic markers. Moving toward healthier dietary habits at the individual level and in publicly-funded institutions, such as schools or hospitals, could help improving public health, reducing healthcare costs and improving community resilience to epidemics (such as COVID-19), which predominantly affects individuals with metabolic diseases.

Whole-Grain Consumption Does Not Affect Obesity Measures: An Updated Systematic Review and Meta-analysis of Randomized Clinical Trials

Since the release of a previous meta-analysis on the effect of whole-grain intake on obesity measures, several clinical trials have been published. Therefore, we aimed to update the previous meta-analysis on the effect of whole-grain intake on obesity measures by including recently published studies, as well as considering the main limitations in that analysis. We searched the online databases of PubMed, Scopus, Clarivate Web of Science, EmBase, and Google Scholar for relevant studies published up to February 2019, using relevant keywords. Randomized clinical trials investigating the effect of whole-grain products or diets high in whole-grain foods, compared with a control diet, on anthropometric measures [including body weight, BMI, waist circumference, and fat mass (FM)] were included. In total, 21 studies with a total sample of 1798 participants, aged ≥18 years, were considered. Based on 22 effect sizes from 19 studies on body weight, with a total sample of 1698 adults, we found no significant effect of whole-grain consumption on body weight. The same findings were obtained for BMIs, such that using 10 effect sizes from 10 clinical trials with a total sample of 769 individuals we did not find any significant effect. With regards to body fat percentage [weighted mean difference (WMD): 0.27; 95% CI: -0.05 to 0.58%; P = 0.09], FM (WMD: 0.45; 95% CI: -0.12 to 1.02 kg; P = 0.12), fat-free mass (WMD: 0.31; 95% CI: -0.67 to 0.06 kg; P = 0.10), and waist circumference (WMD: 0.06; 95% CI: -0.50 to 0.63 cm; P = 0.82), we failed to find any significant effect of whole-grain consumption. In conclusion, our findings did not support current recommendations of whole-grain intake in attempts to control obesity measures. Given the beneficial effects of whole-grain intake on other measures of human health, additional well-designed studies are required to further investigate the effect on obesity. The protocol has been registered with PROSPERO (registration number CRD42019125320).

Whole Grain Wheat Consumption Affects Postprandial Inflammatory Response in a Randomized Controlled Trial in Overweight and Obese Adults with Mild Hypercholesterolemia in the Graandioos Study

BACKGROUND

Whole grain wheat (WGW) consumption is associated with health benefits in observational studies. However, WGW randomized controlled trial (RCT) studies show mixed effects.

OBJECTIVES

The health impact of WGW consumption was investigated by quantification of the body's resilience, which was defined as the "ability to adapt to a standardized challenge."

METHODS

A double-blind RCT was performed with overweight and obese (BMI: 25-35 kg/m2) men (n = 19) and postmenopausal women (n = 31) aged 45-70 y, with mildly elevated plasma total cholesterol (>5 mmol/L), who were randomly assigned to either 12-wk WGW (98 g/d) or refined wheat (RW). Before and after the intervention a standardized mixed-meal challenge was performed. Plasma samples were taken after overnight fasting and postprandially (30, 60, 120, and 240 min). Thirty-one biomarkers were quantified focusing on metabolism, liver, cardiovascular health, and inflammation. Linear mixed-models evaluated fasting compared with postprandial intervention effects. Health space models were used to evaluate intervention effects as composite markers representing resilience of inflammation, liver, and metabolism.

RESULTS

Postprandial biomarker changes related to liver showed decreased alanine aminotransferase by WGW (P = 0.03) and increased β-hydroxybutyrate (P = 0.001) response in RW. Postprandial changes related to inflammation showed increased C-reactive protein (P = 0.001), IL-6 (P = 0.02), IL-8 (P = 0.007), and decreased IL-1B (P = 0.0002) in RW and decreased C-reactive protein (P < 0.0001), serum amyloid A (P < 0.0001), IL-8 (P = 0.02), and IL-10 (P < 0.0001) in WGW. Health space visualization demonstrated diminished inflammatory (P < 0.01) and liver resilience (P < 0.01) by RW, whereas liver resilience was rejuvenated by WGW (P < 0.05).

CONCLUSIONS

Twelve-week 98 g/d WGW consumption can promote liver and inflammatory resilience in overweight and obese subjects with mildly elevated plasma cholesterol. The health space approach appeared appropriate to evaluate intervention effects as composite markers. This trial was registered at www.clinicaltrials.gov as NCT02385149.

The Relationship between Whole Grain Intake and Body Weight: Results of Meta-Analyses of Observational Studies and Randomized Controlled Trials

Results from some observational studies suggest that higher whole grain (WG) intake is associated with lower risk of weight gain. Ovid Medline was used to conduct a literature search for observational studies and randomized controlled trials (RCTs) assessing WG food intake and weight status in adults. A meta-regression analysis of cross-sectional data from 12 observational studies (136,834 subjects) and a meta-analysis of nine RCTs (973 subjects) was conducted; six prospective cohort publications were qualitatively reviewed. Cross-sectional data meta-regression results indicate a significant, inverse correlation between WG intake and body mass index (BMI): weighted slope, −0.0141 kg/m² per g/day of WG intake (95% confidence interval (CI): −0.0207, −0.0077; r = −0.526, p = 0.0001). Prospective cohort results generally showed inverse associations between WG intake and weight change with typical follow-up periods of five to 20 years. RCT meta-analysis results show a nonsignificant pooled standardized effect size of −0.049 kg (95% CI −0.297, 0.199, p = 0.698) for mean difference in weight change (WG versus control interventions). Higher WG intake is significantly inversely associated with BMI in observational studies but not RCTs up to 16 weeks in length; RCTs with longer intervention periods are warranted.

Findings From the Meta-analysis on Whole-Grain Consumption and Biomarkers of Systemic Inflammation Are Misleading

We have with great interest read the recent article by Hajihashemi et al. which systematically reviewed and meta-analyzed a number of published clinical trials about the effect of whole grains on serum levels of hs-CRP (high sensitiviy C-reactive protein), IL-6 (interlukin-6), TNF-α (tumor necrosis factor-α). The findings suggested that consumption of whole grains significantly decreased serum levels of hs-CRP and IL-6, but not TNF-α, compared with the control group. It is an interesting study, but there are some methodological limitations and missing data that need to be addressed. Therefore, we believe that the conclusions were misleading and further comprehensive meta-analysis is required to explain the effect of whole grain intake on serum concentrations of inflammatory biomarkers.

Impact of Diet-Modulated Butyrate Production on Intestinal Barrier Function and Inflammation

A major challenge in affluent societies is the increase in disorders related to gut and metabolic health. Chronic over nutrition by unhealthy foods high in energy, fat, and sugar, and low in dietary fibre is a key environmental factor responsible for this development, which may cause local and systemic inflammation. A low intake of dietary fibre is a limiting factor for maintaining a viable and diverse microbiota and production of short-chain fatty acids in the gut. A suppressed production of butyrate is crucial, as this short-chain fatty acid (SCFA) can play a key role not only in colonic health and function but also at the systemic level. At both sites, the mode of action is through mediation of signalling pathways involving nuclear NF-κB and inhibition of histone deacetylase. The intake and composition of dietary fibre modulate production of butyrate in the large intestine. While butyrate production is easily adjustable it is more variable how it influences gut barrier function and inflammatory markers in the gut and periphery. The effect of butyrate seems generally to be more consistent and positive on inflammatory markers related to the gut than on inflammatory markers in the peripheral tissue. This discrepancy may be explained by differences in butyrate concentrations in the gut compared with the much lower concentration at more remote sites.

Wholegrain Intake and Risk of Type 2 Diabetes: Evidence from Epidemiological and Intervention Studies

Type 2 diabetes mellitus (T2DM) is one of the most common metabolic diseases and represents a leading cause of morbidity and mortality because of its related complications. The alarming rise in T2DM prevalence worldwide poses enormous challenges in relation to its social, economic, and a clinical burden requiring appropriate preventive strategies. Currently, lifestyle modifications—including approaches to promote a moderate body weight reduction and to increase regular physical exercise—are the first crucial intervention for T2DM prevention. In the light of the difficulty in reducing body weight and in long-term maintenance of weight loss, quality changes in dietary patterns—in terms of macro and micronutrient composition—can also strongly affect the development of T2DM. This may provide a more practical and suitable preventative approach than simply implementing caloric restriction. Along this line, there is increasing evidence that wholegrain consumption in substitution of refined grains is associated with a reduction of the incidence of several non-communicable chronic diseases. The aim of the present review is to summarize the current evidence from observational and randomized controlled clinical trials on the benefits of wholegrain on T2DM prevention and treatment. Plausible mechanisms by which wholegrain could act on glucose homeostasis and T2DM prevention are also evaluated. Altogether, the totality of the available evidence supports present dietary recommendations promoting wholegrain foods for the prevention and treatment of T2DM.

Effects of Whole-Grain Consumption on Selected Biomarkers of Systematic Inflammation: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Whole grains have potential benefits in preventing cardiovascular diseases and diabetes; nevertheless, results from randomized clinical trials (RCTs) on inflammatory markers are controversial. The aim of this meta-analysis of RCTs was to examine the effect of whole grains on inflammatory markers A systematic literature search was conducted by using the online database of PubMed, Embase, Google Scholar, and Scopus for relevant studies up to November 2017, using Medical Subject Headings and other related keywords. Only studies that compared the effects of whole grains on inflammatory markers with refined grains were included. From more than 2278 articles, 17 RCTs met the inclusion criteria and were systematically reviewed. Weighted mean differences were estimated and pooled effect size was calculated by random effects model. Thirteen RCTs with 466 participants were included in the meta-analysis. Whole-grain consumption had a significant effect on serum concentration of high-sensitivity C-reactive protein (hs-CRP; Hedges' g: -0.22; 95% confidence interval (CI): -0.45, 0.00; p = 0.047), interleukin-6 (IL-6; -0.28 pg/mL; 95% CI: -0.55, -0.02; p = 0.037) but did not result in a significant decline in serum concentration of tumor necrosis factor alpha (TNF-α; -0.12 pg/mL; 95% CI: -0.39, 0.15; p = 0.396). Significant heterogeneity was observed between studies for hs-CRP (I² = 69.0%, p < 0.0001), IL-6 (I² = 96.6%, p < 0.001), and TNF-α (I² =  95.4%, p < 0.001). In sensitivity analysis, the effect of whole grain intake on hs-CRP, IL-6, and TNF-α was not substantially modified by the result of a single study. Meta-regression for duration showed no significant association between the duration of study and changes in serum C-reactive protein levels (β coefficient = 0.006, standard error = 0.036; p = 0.870). Conclusions: This meta-analysis of RCTs suggested that whole grains might affect health status via improving systematic inflammation. Key teaching points: We conducted a systematic review and meta-analysis of randomized controlled trials. Whole grains consumption was associated with lower serum levels of hs-CRP and IL-6. Whole grains cannot significantly decrease serum levels of TNF-α. We could not found any source for heterogeneity. The effect of whole grains on serum inflammatory biomarkers was independent from duration.

Food groups and intermediate disease markers: a systematic review and network meta-analysis of randomized trials

Background

In previous meta-analyses of prospective observational studies, we investigated the association between food groups and risk of chronic disease.

Objective

The aim of the present network meta-analysis (NMA) was to assess the effects of these food groups on intermediate-disease markers across randomized intervention trials.

Design

Literature searches were performed until January 2018. The following inclusion criteria were defined a priori: 1) randomized trial (≥4 wk duration) comparing ≥2 of the following food groups: refined grains, whole grains, nuts, legumes, fruits and vegetables, eggs, dairy, fish, red meat, and sugar-sweetened beverages (SSBs); 2) LDL cholesterol and triacylglycerol (TG) were defined as primary outcomes; total cholesterol, HDL cholesterol, fasting glucose, glycated hemoglobin, homeostasis model assessment insulin resistance, systolic and diastolic blood pressure, and C-reactive protein were defined as secondary outcomes. For each outcome, a random NMA was performed, and for the ranking, the surface under the cumulative ranking curves (SUCRA) was determined.

Results

A total of 66 randomized trials (86 reports) comparing 10 food groups and enrolling 3595 participants was identified. Nuts were ranked as the best food group at reducing LDL cholesterol (SUCRA: 93%), followed by legumes (85%) and whole grains (70%). For reducing TG, fish (97%) was ranked best, followed by nuts (78%) and red meat (72%). However, these findings are limited by the low quality of the evidence. When combining all 10 outcomes, the highest SUCRA values were found for nuts (66%), legumes (62%), and whole grains (62%), whereas SSBs performed worst (29%).

Conclusion

The present NMA provides evidence that increased intake of nuts, legumes, and whole grains is more effective at improving metabolic health than other food groups. For the credibility of diet-disease relations, high-quality randomized trials focusing on well-established intermediate-disease markers could play an important role. This systematic review was registered at PROSPERO (www.crd.york.ac.uk/PROSPERO) as CRD42018086753.

Evaluating Whole Grain Intervention Study Designs and Reporting Practices Using Evidence Mapping Methodology

Consumption of whole grains have been associated with reduced risk of chronic diseases in many observational studies; yet, results of intervention studies are mixed. We aimed to use evidence mapping to capture the methodological and reporting variability in whole grain intervention studies that may contribute to this inconsistency. We conducted a reproducible search in OVID Medline for whole grain human intervention studies (published 1946 to February 2018). After screening based on a priori criteria, we identified 202 publications describing a total of 213 unique trials. Over half (55%) were acute trials, lasting ≤1 day, 30% were moderate duration studies (up to 6 weeks) and 15% were of longer duration (more than 6 weeks). The majority of acute trials (75%) examined measures of glycaemia and/or insulinemia, while most of the longer trials included measures of cardiometabolic health (71%), appetite/satiety (57%) and weight/adiposity (56%). Among the moderate and long duration trials, there was a wide range of how whole grains were described but only 10 publications referenced an established definition. Only 55% of trials reported the actual amount of whole grains (in grams or servings), while 36% reported the amount of food/product and 9% did not report a dose at all. Of the interventions that provided a mixture of whole grains, less than half (46%) reported the distribution of the different grain types. Reporting of subject compliance also varied and only 22% used independent biomarkers of whole grain intake. This evidence map highlights the need to standardize both study protocols and reporting practices to support effective synthesis of study results and provide a stronger foundation to better inform nutrition scientists and public health policy.

Dietary Fibre as a Unifying Remedy for the Whole Spectrum of Obesity-Associated Cardiovascular Risk

Obesity is a pandemic carrying the heavy burden of multiple and serious co-morbidities including metabolic syndrome, type 2 diabetes and cardiovascular diseases. The pathophysiological processes leading to the accumulation of body fat slowly evolve to fat accumulation in other body compartments than subcutaneous tissue. This abnormal fat deposition determines insulin resistance which in turn causes blood glucose and lipid metabolism derangement, non-alcoholic fatty liver disease, hypertension, and metabolic syndrome. All these conditions contribute to increase the cardiovascular risk of obese people. Several randomized clinical trials demonstrated that moderate weight loss (5⁻10%) in obese patients improves obesity-related metabolic risk factors and coexisting disorders. Therefore, nutritional strategies able to facilitate weight management, and in the meantime positively influence obesity-associated cardiovascular risk factors, should be implemented. To this aim, a suitable option could be dietary fibres that may also act independently of weight loss. The present narrative review summarizes the current evidence about the effects of dietary fibres on weight management in obese people. Moreover, all of the different cardiovascular risk factors are individually considered and evidence on cardiovascular outcomes is summarized. We also describe the plausible mechanisms by which different dietary fibres could modulate cardio-metabolic risk factors. Overall, despite both epidemiological and intervention studies on weight loss that show statistically significant but negligible clinical effects, dietary fibres seem to have a beneficial impact on main pathophysiological pathways involved in cardiovascular risk (i.e., insulin resistance, renin-angiotensin, and sympathetic nervous systems). Although the evidence is not conclusive, this suggests that fibre would be a suitable option to counteract obesity-related cardio-metabolic diseases also independently of weight loss. However, evidence is not consistent for the different risk factors, with clear beneficial effects shown on blood glucose metabolism and Low Density Lipoprotein (LDL) cholesterol while there is fewer, and less consistent data shown on plasma triglyceride and blood pressure. Ascribing the beneficial effect of some foods (i.e., fruits and vegetables) solely to their fibre content requires more investigation on the pathophysiological role of other dietary components, such as polyphenols.

The effect of dietary glycemic index and glycemic load on inflammatory biomarkers: a systematic review and meta-analysis of randomized clinical trials

Background

To our knowledge, there is no study available that summarizes earlier findings on the effect of dietary glycemic index (GI) and glycemic load (GL) on inflammatory biomarkers.

Objective

This systematic review and meta-analysis was conducted to systematically review the available clinical trials that examined the effects of low-GI (LGI) and low-GL (LGL) diets on several inflammatory biomarkers in adults.

Design

We searched for relevant articles published up to June 2017 through PubMed, Medline, SCOPUS, EMBASE, and Google Scholar with the use of relevant keywords. Clinical trials that examined the effect of dietary GI and GL on inflammation in adults were included.

Results

Overall, 28 randomized controlled trials (RCTs) including 2961 participants (59% women, 41% men) were included in this meta-analysis. By combining findings from 14 studies on high-sensitivity C-reactive protein (hs-CRP) concentrations, we found no significant effect of LGI or LGL diets on serum hs-CRP concentrations compared with the control diet [weighted mean difference (WMD) for dietary GI: -0.05 mg/L (95% CI: -0.21, 0.10 mg/L); and WMD for dietary GL: 0.08 mg/L (95% CI: -0.26, 0.42 mg/L), respectively]. After combining effect sizes from 5 studies, we did not find significant changes in serum tumor necrosis factor α (TNF-α) concentrations comparing control diets with LGI (WMD: -0.18 mg/L; 95% CI: -0.43, 0.06 mg/L) or LGL (WMD: -0.20 mg/L; 95% CI: -0.33, 0.07 mg/L) diets. Significant changes were also not seen in leptin and interleukin 6 (IL-6) concentrations after the consumption of LGI or LGL diets.

Conclusions

We did not find any significant effect of dietary GI or GL on serum concentrations of inflammatory cytokines, including hs-CRP, leptin, IL-6, and TNF-α in adults. Additional RCTs-in particular, feeding trials-are required to shed light on this issue.

Whole grain cereals for the primary or secondary prevention of cardiovascular disease

BACKGROUND

There is evidence from observational studies that whole grains can have a beneficial effect on risk for cardiovascular disease (CVD). Earlier versions of this review found mainly short-term intervention studies. There are now longer-term randomised controlled trials (RCTs) available. This is an update and expansion of the original review conducted in 2007.

OBJECTIVES

The aim of this systematic review was to assess the effect of whole grain foods or diets on total mortality, cardiovascular events, and cardiovascular risk factors (blood lipids, blood pressure) in healthy people or people who have established cardiovascular disease or related risk factors, using all eligible RCTs.

SEARCH METHODS

We searched CENTRAL (Issue 8, 2016) in the Cochrane Library, MEDLINE (1946 to 31 August 2016), Embase (1980 to week 35 2016), and CINAHL Plus (1937 to 31 August 2016) on 31 August 2016. We also searched ClinicalTrials.gov on 5 July 2017 and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) on 6 July 2017. We checked reference lists of relevant articles and applied no language restrictions.

SELECTION CRITERIA

We selected RCTs assessing the effects of whole grain foods or diets containing whole grains compared to foods or diets with a similar composition, over a minimum of 12 weeks, on cardiovascular disease and related risk factors. Eligible for inclusion were healthy adults, those at increased risk of CVD, or those previously diagnosed with CVD.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies. Data were extracted and quality-checked by one review author and checked by a second review author. A second review author checked the analyses. We assessed treatment effect using mean difference in a fixed-effect model and heterogeneity using the I² statistic and the Chi² test of heterogeneity. We assessed the overall quality of evidence using GRADE with GRADEpro software.

MAIN RESULTS

We included nine RCTs randomising a total of 1414 participants (age range 24 to 70; mean age 45 to 59, where reported) to whole grain versus lower whole grain or refined grain control groups. We found no studies that reported the effect of whole grain diets on total cardiovascular mortality or cardiovascular events (total myocardial infarction, unstable angina, coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty, total stroke). All included studies reported the effect of whole grain diets on risk factors for cardiovascular disease including blood lipids and blood pressure. All studies were in primary prevention populations and had an unclear or high risk of bias, and no studies had an intervention duration greater than 16 weeks.Overall, we found no difference between whole grain and control groups for total cholesterol (mean difference 0.07, 95% confidence interval -0.07 to 0.21; 6 studies (7 comparisons); 722 participants; low-quality evidence).Using GRADE, we assessed the overall quality of the available evidence on cholesterol as low. Four studies were funded by independent national and government funding bodies, while the remaining studies reported funding or partial funding by organisations with commercial interests in cereals.

AUTHORS' CONCLUSIONS

There is insufficient evidence from RCTs of an effect of whole grain diets on cardiovascular outcomes or on major CVD risk factors such as blood lipids and blood pressure. Trials were at unclear or high risk of bias with small sample sizes and relatively short-term interventions, and the overall quality of the evidence was low. There is a need for well-designed, adequately powered RCTs with longer durations assessing cardiovascular events as well as cardiovascular risk factors.

Substituting whole grains for refined grains in a 6-wk randomized trial favorably affects energy-balance metrics in healthy men and postmenopausal women

Background: The effect of whole grains on the regulation of energy balance remains controversial.Objective: We aimed to determine the effects of substituting whole grains for refined grains, independent of body weight changes, on energy-metabolism metrics and glycemic control.Design: The study was a randomized, controlled, parallel-arm controlled-feeding trial that was conducted in 81 men and postmenopausal women [49 men and 32 women; age range: 40-65 y; body mass index (in kg/m²): <35.0]. After a 2-wk run-in period, participants were randomly assigned to consume 1 of 2 weight-maintenance diets for 6 wk. Diets differed in whole-grain and fiber contents [mean ± SDs: whole grain-rich diet: 207 ± 39 g whole grains plus 40 ± 5 g dietary fiber/d; refined grain-based diet: 0 g whole grains plus 21 ± 3 g dietary fiber/d] but were otherwise similar. Energy metabolism and body-composition metrics, appetite, markers of glycemic control, and gut microbiota were measured at 2 and 8 wk.Results: By design, body weight was maintained in both groups. Plasma alkylresorcinols, which are biomarkers of whole-grain intake, increased in the whole grain-rich diet group (WG) but not in the refined grain-based diet group (RG) (P-diet-by-time interaction < 0.0001). Beta ± SE changes (ΔWG compared with ΔRG) in the resting metabolic rate (RMR) (43 ± 25 kcal/d; P = 0.04), stool weight (76 ± 12 g/d; P < 0.0001), and stool energy content (57 ± 17 kcal/d; P = 0.003), but not in stool energy density, were higher in the WG. When combined, the favorable energetic effects in the WG translated into a 92-kcal/d (95% CI: 28, 156-kcal/d) higher net daily energy loss compared with that of the RG (P = 0.005). Prospective consumption (P = 0.07) and glycemia after an oral-glucose-tolerance test (P = 0.10) trended toward being lower in the WG than in the RG. When nonadherent participants were excluded, between-group differences in stool energy content and glucose tolerance increased, and between-group differences in the RMR and prospective consumption were not statistically significant.Conclusion: These findings suggest positive effects of whole grains on the RMR and stool energy excretion that favorably influence energy balance and may help explain epidemiologic associations between whole-grain consumption and reduced body weight and adiposity. This trial was registered at clinicaltrials.gov as NCT01902394.

Intakes of whole grain in an Italian sample of children, adolescents and adults

PURPOSE

There is wide evidence that regular consumption of whole grain foods may reduce the risk of chronic diseases. The aim of this work was to quantify the intake of whole grains and identify main dietary sources in the Italian population.

METHODS

Whole grain intakes were calculated in a sample of 2830 adults/older adults and of 440 children/adolescents from the last national survey INRAN-SCAI 2005-06. Food consumption was assessed from a 3-day food record. The whole grain content of foods was estimated mainly from quantitative ingredient declarations on labels.

RESULTS

Mean whole grain intakes were 3.7 g/day in adults/older adults and 2.1 g/day in children/adolescents. Overall, 23 % of the sample reported consumption of whole grain foods during the survey, among which mean whole grain intakes ranged from 6.0 g/day in female children to 19.1 g/day in female older adults. The main sources of whole grains were breakfast cereals in children/adolescents (32 %) and bread in adults/older adults (46 %). Consumption of whole grain among adults was associated with significantly higher daily intakes and adequacy of dietary fibre, several vitamins (thiamine, riboflavin, vitamin B6) and minerals (iron, calcium, potassium, phosphorus, zinc, magnesium) compared to non-consumption. Among children, whole grain intake was associated with significantly higher intakes of iron and magnesium.

CONCLUSIONS

The study reveals very low whole grain intakes across all age groups of the Italian population. Considering the positive association in consumers between whole grain intakes and fibre and micro-nutrient intakes, public health strategies to increase whole grain consumption should be considered.

Effects of a diet rich in arabinoxylan and resistant starch compared with a diet rich in refined carbohydrates on postprandial metabolism and features of the metabolic syndrome

PURPOSE

Low intake of dietary fibre is associated with the development of type 2 diabetes. Dyslipidaemia plays a key role in the pathogenesis of type 2 diabetes. Knowledge of the impact of dietary fibres on postprandial lipaemia is, however, sparse. This study aimed in subjects with metabolic syndrome to assess the impact on postprandial lipaemia and features of the metabolic syndrome of a healthy carbohydrate diet (HCD) rich in cereal fibre, arabinoxylan and resistant starch compared to a refined-carbohydrate western-style diet (WSD).

METHODS

Nineteen subjects completed the randomised, crossover study with HCD and WCD for 4-week. Postprandial metabolism was evaluated by a meal-challenge test and insulin sensitivity was assessed by HOMA-IR and Matsuda index. Furthermore, fasting cholesterols, serum-fructosamine, circulating inflammatory markers, ambulatory blood pressure and intrahepatic lipid content were measured.

RESULTS

We found no diet effects on postprandial lipaemia. However, there was a significant diet × statin interaction on total cholesterol (P = 0.02) and LDL cholesterol (P = 0.002). HCD decreased total cholesterol (-0.72 mmol/l, 95% CI (-1.29; -0.14) P = 0.03) and LDL cholesterol (-0.61 mmol/l, 95% CI (-0.86; -0.36) P = 0.002) compared with WSD in subjects on but not without statin treatment. We detected no other significant diet effects.

CONCLUSIONS

In subjects with metabolic syndrome on statins a 4-week diet rich in arabinoxylan and resistant starch improved fasting LDL and total cholesterol compared to subjects not being on statins. However, we observed no diet related impact on postprandial lipaemia or features of the metabolic syndrome. The dietary fibre x statin interaction deserves further elucidation.

Phytochemical Pharmacokinetics and Bioactivity of Oat and Barley Flour: A Randomized Crossover Trial

While dietary fiber plays an important role in the health benefits associated with whole grain consumption, other ingredients concentrated in the outer bran layer, including alkylresorcinols, lignans, phenolic acids, phytosterols, and tocols, may also contribute to these outcomes. To determine the acute bioavailability and pharmacokinetics of the major phytochemicals found in barley and oats, we conducted a randomized, three-way crossover trial in 13 healthy subjects, aged 40–70 years with a body mass index (BMI) of 27–35.9 kg/m². After a two-day run-in period following a diet low in phytochemicals, subjects were randomized to receive muffins made with either 48 g whole oat flour, whole barley flour, or refined wheat flour plus cellulose (control), with a one-week washout period between each intervention. At the same time, an oral glucose tolerance test was administered. In addition to plasma phytochemical concentrations, glucose and insulin responses, biomarkers of antioxidant activity, lipid peroxidation, inflammation, and vascular remodeling were determined over a 24-h period. There was no significant effect on acute bioavailability or pharmacokinetics of major phytochemicals. Administered concurrently with a glucose bolus, the source of whole grains did not attenuate the post-prandial response of markers of glucoregulation and insulin sensitivity, inflammation, nor vascular remodeling compared to the refined grain control. No significant differences were observed in the bioavailability or postprandial effects between whole-oat and whole-barley compared to a refined wheat control when administered with a glucose challenge. These null results may be due, in part, to the inclusion criteria for the subjects, dose of the whole grains, and concurrent acute administration of the whole grains with the glucose bolus.

Urinary Biomarkers of Whole Grain Wheat Intake Identified by Non-targeted and Targeted Metabolomics Approaches

Mounting evidence suggests that whole grain (WG) intake plays an important role in chronic disease prevention. However, numerous human studies have failed to produce clear-cut conclusions on this topic. Here, a combination of non-targeted and targeted metabolomics approaches, together with kinetic studies, was used to investigate biomarkers of WG wheat intake and further explore the diet-disease associations. Via these integrated approaches, forty-one compounds were identified as the most discriminating endogenous metabolites after WG versus refined grain (RG) wheat bread consumption. The corresponding biological assessment of these endogenous changes suggests that, in contrast to RG consumption, WG wheat consumption may facilitate antioxidant defense systems and moderate the risk factors of cancer, cardiovascular diseases, and other chronic diseases. A panel of urinary markers consisting of seven alkylresorcinol metabolites and five benzoxazinoid derivatives as specific biomarkers, as well as five phenolic acid derivatives, was also established to cover multiple time points and longer time periods for correctly and objectively monitoring WG wheat intake. Through these findings, we have established a comprehensive biomarker pool to better assess WG wheat consumption, and to monitor the endogenous changes that are linked to health effects of WG wheat consumption.

Addition of Orange Pomace to Orange Juice Attenuates the Increases in Peak Glucose and Insulin Concentrations after Sequential Meal Ingestion in Men with Elevated Cardiometabolic Risk

BACKGROUND

Prospective cohort studies show that higher dietary fiber intake is associated with reduced cardiovascular disease risk, yet the impact on postprandial glucose and insulin responses is unclear.

OBJECTIVE

This study aims to evaluate the effects of orange beverages with differing fiber concentrations on postprandial glycemic responses (secondary outcome measure) after a sequential breakfast and lunch challenge in men with increased cardiometabolic risk.

METHODS

Thirty-six men (aged 30-65 y; body mass index 25-30 kg/m(2): fasting triacylglycerol or total cholesterol concentrations: 0.8-2.2 or 6.0-8.0 mmol/L, respectively) were provided with a high-fat mixed breakfast and were randomly assigned to consume 240 mL Tropicana (PepsiCo, Inc.) pure premium orange juice without pulp (OJ), OJ with 5.5 g added orange pomace fiber (OPF), juice made from lightly blended whole orange, or an isocaloric sugar-matched control (Control) on 4 occasions separated by 2 wk. A medium-fat mixed lunch was provided at 330 min. Blood samples were collected before breakfast and on 11 subsequent occasions for 420 min (3 time points postlunch) to determine postprandial glucose, insulin, lipid, and inflammatory biomarker responses. Repeated-measures ANOVA was used for data analysis.

RESULTS

OPF significantly (P < 0.05) reduced the maximal change in glucose concentrations (1.9 ± 0.21 mmol/L) reached after breakfast compared with other treatments (2.3-2.4 mmol/L) and after lunch (3.0 ± 0.05 mmol/L) compared with OJ (3.6 ± 0.05 mmol/L). The maximal change in insulin concentration (313 ± 25 pmol/L) was also lower compared with Control (387 ± 30 pmol/L) and OJ (418 ± 39 pmol/L) after breakfast. OPF significantly delayed the time to reach the peak glucose concentration compared with Control and OJ, and of insulin compared with Control after breakfast.

CONCLUSION

OPF consumed with breakfast may lower postprandial glycemic and insulinemic responses to typical meal ingestion in men with increased cardiometabolic risk. This trial is registered at clinicaltrials.gov as NCT01963416.

[Effects of Dietary and Physical Activity Interventions on Metabolic Syndrome: A Meta-analysis]

PURPOSE

This study identified effects of dietary and physical activity interventions including dietary interventions or physical activity interventions alone or combined dietary-physical activity interventions to improve symptoms in metabolic syndrome including abdominal obesity, high triglycerides, low high density lipoprotein cholesterol, elevated blood pressure, and elevated fasting glucose through meta-analysis.

METHODS

Articles on metabolic syndrome X published from 1988 to 2013 were searched through electronic databases, Google Scholar, and reference reviews. Methodological quality was assessed by the checklist, SIGN (Scottish Intercollegiate Guidelines Network).

RESULTS

In the meta-analysis, there were 9 articles reporting 13 interventions with 736 participants. Using random effect models, the dietary and/or physical activity interventions showed a lower mean difference in waist circumference (-1.30 cm, 95% CI:-2.44~-0.15, p=.027). The combined dietary-physical activity interventions showed a lower mean difference in waist circumference (-2.77 cm, 95% CI:-4.77~-0.76, p=.007) and systolic blood pressure (-5.44 mmHg, 95% CI:-10.76~-0.12, p=.044). Additionally, interventions of over 24 weeks yielded a lower mean difference in waist circumference (-2.78 cm, 95% CI:-4.69~-0.87, p=.004) and diastolic blood pressure (-1.93 mmHg, 95% CI:-3.63~-0.22, p=.026).

CONCLUSION

The findings indicate that dietary and/or physical activity interventions for metabolic syndrome reduce central obesity with no adverse effects. This finding provides objective evidences for dietary and physical activity management on metabolic syndrome as an efficient intervention.

Polyphenols and Glycemic Control

Growing evidence from animal studies supports the anti-diabetic properties of some dietary polyphenols, suggesting that dietary polyphenols could be one dietary therapy for the prevention and management of Type 2 diabetes. This review aims to address the potential mechanisms of action of dietary polyphenols in the regulation of glucose homeostasis and insulin sensitivity based on in vitro and in vivo studies, and to provide a comprehensive overview of the anti-diabetic effects of commonly consumed dietary polyphenols including polyphenol-rich mixed diets, tea and coffee, chocolate and cocoa, cinnamon, grape, pomegranate, red wine, berries and olive oil, with a focus on human clinical trials. Dietary polyphenols may inhibit α-amylase and α-glucosidase, inhibit glucose absorption in the intestine by sodium-dependent glucose transporter 1 (SGLT1), stimulate insulin secretion and reduce hepatic glucose output. Polyphenols may also enhance insulin-dependent glucose uptake, activate 5' adenosine monophosphate-activated protein kinase (AMPK), modify the microbiome and have anti-inflammatory effects. However, human epidemiological and intervention studies have shown inconsistent results. Further intervention studies are essential to clarify the conflicting findings and confirm or refute the anti-diabetic effects of dietary polyphenols.

Effects of different dietary approaches on inflammatory markers in patients with metabolic syndrome: A systematic review and meta-analysis

OBJECTIVE

Chronic low-grade inflammation has been associated with insulin resistance, diabetes, atherosclerosis, obesity, and metabolic syndrome (MetS). A proinflammatory environment contributes to several metabolic disturbances and possibly the development of MetS. Dietary approaches have defined impact on immune function and putative antiinflammatory effects. The aim of this study was to assess the effects of different dietary approaches on markers of inflammation in patients with MetS. Further effects on weight loss and fasting insulin were analyzed.

METHODS

Medline/PubMed, Scopus, and the Cochrane Library were screened in September 2014 for randomized controlled trials (RCTs) on different dietary approaches for participants with MetS as defined by National Cholesterol Education Program Adult Treatment Panel III. Primary outcomes were markers of the immune system. Secondary outcome was body weight and fasting insulin. Standardized mean differences (SMD) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

Thirteen randomized controlled trials with a total of 2017 patients were included. Low-fat diets (29 ± 2% energy from fats) decreased C-reactive protein compared with control diets (SMD: -0.98; 95% CI: -1.6 to -0.35; P = 0.002). Low-carbohydrate diets (23 ± 10% energy from carbohydrates; SMD: -0.33; 95% CI: -0.63 to -0.03; P = 0.004) and multimodal interventions (SMD: -1.02; 95% CI: -1.97 to -0.07; P = 0.04) were able to induce significant weight loss. Low-carbohydrate diets were able to decrease insulin (SMD: -0.33; 95% CI: -0.63 to -0.03; P = 0.03).

CONCLUSIONS

C-reactive protein; however, this effect is also dependent on weight loss. Furthermore, low-carbohydrate diets have beneficial effects on insulin and body weight. Dietary approaches should mainly be tried to reduce macronutrients and enrich functional food components such as vitamins, flavonoids, and unsaturated fatty acids. People with MetS will benefit most by combining weight loss and anti-inflammatory nutrients.

Whole-grain products and whole-grain types are associated with lower all-cause and cause-specific mortality in the Scandinavian HELGA cohort

No study has yet investigated the intake of different types of whole grain (WG) in relation to all-cause and cause-specific mortality in a healthy population. The aim of the present study was to investigate the intake of WG products and WG types in relation to all-cause and cause-specific mortality in a large Scandinavian HELGA cohort that, in 1992–8, included 120 010 cohort members aged 30–64 years from the Norwegian Women and Cancer Study, the Northern Sweden Health and Disease Study, and the Danish Diet Cancer and Health Study. Participants filled in a FFQ from which data on the intake of WG products were extracted. The estimation of daily intake of WG cereal types was based on country-specific products and recipes. Mortality rate ratios (MRR) and 95 % CI were estimated using the Cox proportional hazards model. A total of 3658 women and 4181 men died during the follow-up (end of follow-up was 15 April 2008 in the Danish sub-cohort, 15 December 2009 in the Norwegian sub-cohort and 15 February 2009 in the Swedish sub-cohort). In the analyses of continuous WG variables, we found lower all-cause mortality with higher intake of total WG products (women: MRR 0·89 (95 % CI 0·86, 0·91); men: MRR 0·89 (95 % CI 0·86, 0·91) for a doubling of intake). In particular, intake of breakfast cereals and non-white bread was associated with lower mortality. We also found lower all-cause mortality with total intake of different WG types (women: MRR 0·88 (95 % CI 0·86, 0·92); men: MRR 0·88 (95 % CI 0·86, 0·91) for a doubling of intake). In particular, WG oat, rye and wheat were associated with lower mortality. The associations were found in both women and men and for different causes of deaths. In the analyses of quartiles of WG intake in relation to all-cause mortality, we found lower mortality in the highest quartile compared with the lowest for breakfast cereals, non-white bread, total WG products, oat, rye (only men), wheat and total WG types. The MRR for highest v. lowest quartile of intake of total WG products was 0·68 (95 % CI 0·62, 0·75, Ptrend over quartiles< 0·0001) for women and 0·75 (95 % CI 0·68, 0·81, Ptrend over quartiles< 0·0001) for men. The MRR for highest v. lowest quartile of intake of total WG types was 0·74 (95 % CI 0·67, 0·81, Ptrend over quartiles< 0·0001) for women and 0·75 (95 % CI 0·68, 0·82, Ptrend over quartiles< 0·0001) for men. Despite lower statistical power, the analyses of cause-specific mortality according to quartiles of WG intake supported these results. In conclusion, higher intake of WG products and WG types was associated with lower mortality among participants in the HELGA cohort. The study indicates that intake of WG is an important aspect of diet in preventing early death in Scandinavia.

Relationship between bread and obesity

Some studies have indicated that promoting the Mediterranean diet pattern as a model of healthy eating may help to prevent weight gain and the development of overweight/obesity. Bread consumption, which has been part of the traditional Mediterranean diet, has continued to decline in Spain and in the rest of the world, because the opinion of the general public is that bread fattens. The present study was conducted to assess whether or not eating patterns that include bread are associated with obesity and excess abdominal adiposity, both in the population at large or in subjects undergoing obesity management. The results of the present review indicate that reducing white bread, but not whole-grain bread, consumption within a Mediterranean-style food pattern setting is associated with lower gains in weight and abdominal fat. It appears that the different composition between whole-grain bread and white bread varies in its effect on body weight and abdominal fat. However, the term ‘whole-grain bread’ needs to be defined for use in epidemiological studies. Finally, additional studies employing traditional ways of bread production should analyse this effect on body-weight and metabolic regulation.

Low-energy diets differing in fibre, red meat and coffee intake equally improve insulin sensitivity in type 2 diabetes: a randomised feasibility trial

AIMS/HYPOTHESIS

Epidemiological studies have found that a diet high in fibre and coffee, but low in red meat, reduces the risk for type 2 diabetes. We tested the hypothesis that these nutritional modifications differentially improve whole-body insulin sensitivity (primary outcome) and secretion.

METHODS

Inclusion criteria were: age 18-69 years, BMI ≥ 30 kg/m(2), type 2 diabetes treated with diet, metformin or acarbose and known disease duration of ≤ 5 years. Exclusion criteria were: HbA1c >75 mmol/mol (9.0%), type 1 or secondary diabetes types and acute or chronic diseases including cancer. Patients taking any medication affecting the immune system or insulin sensitivity, other than metformin, were also excluded. Of 59 patients (randomised using randomisation blocks [four or six patients] with consecutive numbers), 37 (54% female) obese type 2 diabetic patients completed this controlled parallel-group 8-week low-energy dietary intervention. The participants consumed either a diet high in cereal fibre (whole grain wheat/rye: 30-50 g/day) and coffee (≥ 5 cups/day), and free of red meat (L-RISK, n = 17) or a diet low in fibre (≤ 10 g/day), coffee-free and high in red meat (≥ 150 g/day) diet (H-RISK, n = 20). Insulin sensitivity and secretion were assessed by hyperinsulinaemic-euglycaemic clamp and intravenous glucose tolerance tests with isotope dilution. Whole-body and organ fat contents were measured by magnetic resonance imaging and spectroscopy.

RESULTS

Whole-body insulin sensitivity increased in both groups (mean [95% CI]) (H-RISK vs L-RISK: 0.8 [0.2, 1.4] vs 1.0 [0.4, 1.7]mg kg(-1) min(-1), p = 0.59), while body weight decreased (-4.8% [-6.1%, -3.5%] vs -4.6% [-6.0%, -3.3%], respectively). Hepatic insulin sensitivity remained unchanged, whereas hepatocellular lipid content fell in both groups (-7.0% [-9.6%, -4.5%] vs -6.7% [-9.5%, -3.9%]). Subcutaneous fat mass (-1,553 [-2,767, -340] cm(3) vs -751 [-2,047; 546] cm(3), respectively) visceral fat mass (-206 [-783, 371] cm(3) vs -241 [-856, 373] cm(3), respectively) and muscle fat content (-0.09% [-0.16%, -0.02%] vs -0.02% [-0.10%, 0.05%], respectively) decreased similarly. Insulin secretion remained unchanged, while the proinflammatory marker IL-18 decreased only after the L-RISK diet.

CONCLUSIONS/INTERPRETATION

No evidence of a difference between both low-energy diets was identified. Thus, energy restriction per se seems to be key for improving insulin action in phases of active weight loss in obese type 2 diabetic patients, with a potential improvement of subclinical inflammation with the L-RISK diet.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01409330.

FUNDING

This study was supported by the Ministry of Science and Research of the State of North Rhine-Westphalia (MIWF NRW), the German Federal Ministry of Health (BMG), the Federal Ministry for Research (BMBF) to the Center for Diabetes Research (DZD e.V.) and the Helmholtz Alliance Imaging and Curing Environmental Metabolic Diseases (ICEMED).

Functional foods and cardiometabolic diseases* International Task Force for Prevention of Cardiometabolic Diseases

Mounting evidence supports the hypothesis that functional foods containing physiologically-active components may be healthful. Longitudinal cohort studies have shown that some food classes and dietary patterns are beneficial in primary prevention, and this has led to the identification of putative functional foods. This field, however, is at its very beginning, and additional research is necessary to substantiate the potential health benefit of foods for which the diet-health relationships are not yet scientifically validated. It appears essential, however, that before health claims are made for particular foods, in vivo randomized, double-blind, placebo controlled trials of clinical end-points are necessary to establish clinical efficacy. Since there is need for research work aimed at devising personalized diet based on genetic make-up, it seems more than reasonable the latter be modeled, at present, on the Mediterranean diet, given the large body of evidence of its healthful effects. The Mediterranean diet is a nutritional model whose origins go back to the traditional dietadopted in European countries bordering the Mediterranean sea, namely central and southern Italy, Greece and Spain; these populations have a lower incidence of cardiovascular diseases than the North American ones, whose diet is characterized by high intake of animal fat. The meeting in Naples and this document both aim to focus on the changes in time in these two different models of dietary habits and their fall out on public health.

Consumption of whole grains in French children, adolescents and adults

The consumption of whole grain foods is associated with many nutritional, health and weight control benefits. The present study assessed whole grain intake in France on the basis of a 7 d dietary survey in a representative sample of children, adolescents and adults (Comportements et Consommations Alimentaires en France 2010 survey). Special care was taken to identify and assess the intake of all whole grains. All foods consumed were considered, with no lower limit on whole grain content. For the majority of foods, details regarding the whole grain contents were obtained from brand information and quantitative nutrient declarations on food labels. Over half of the respondents reported never consuming any whole grain. In participants who did, consumption levels were very low (about 9·1 g/d in children and 14·4 g/d in adults). The main food sources of whole grains were breakfast cereals in children and adolescents and bread in adults. Consumers of whole grains had higher daily intakes of fibre and several vitamins and minerals than non-consumers. In adults but not in children, the OR for overweight/obesity decreased significantly as the level of whole grain consumption increased. Although a majority of French consumers comply with the national recommendation to consume a starchy food with each meal, they do so with minimal consumption of whole grain foods.

Postprandial glucose metabolism and SCFA after consuming wholegrain rye bread and wheat bread enriched with bioprocessed rye bran in individuals with mild gastrointestinal symptoms

Background

Rye bread benefits glucose metabolism. It is unknown whether the same effect is achieved by rye bran-enriched wheat bread. We tested whether white wheat bread enriched with bioprocessed rye bran (BRB + WW) and sourdough wholegrain rye bread (WGR) have similar effects on glucose metabolism and plasma level of short chain fatty acids (SCFAs).

Methods

Twenty-one (12 women) of 23 recruited subjects completed an intervention with a four-week run-in and two four-week test periods in cross-over design. White wheat bread (WW; 3% fibre) was consumed during the run-in, and WGR and BRB + WW (10% fibre) during the test periods. A meal test providing 51/33/11 E % from carbohydrates/fat/protein was conducted at the end of each period. Fasting and postprandial plasma samples were analysed for glucose, insulin, and SCFA.

Results

Glucose and insulin responses and plasma concentrations of SCFAs to the meal test were similar between the WGR and BRB + WW periods. When compared to the WW period, postprandial insulin concentration at 120 min was lower (p = 0.023) and the first-phase insulin secretion improved (p = 0.033) only after the WGR period, whereas postprandial concentrations of butyrate (p < 0.05) and propionate (p = 0.009) at 30 min increased during both rye bread periods.

Conclusions

Beneficial effects of WGR over white wheat bread on glucose and SCFA production were confirmed. The enrichment of the white wheat bread with bioprocessed rye bran (BRB + WW) yielded similar but not as pronounced effects than WGR when compared to WW alone. Postprandially measured glucose metabolism and concentrations of SCFAs provided additional information along with fasting measurements.