A randomized crossover study to assess the effect of an oat-rich diet on glycaemic control, plasma lipids and postprandial glycaemia, inflammation and oxidative stress in Type 2 diabetes

Use of ancient grains for the management of diabetes mellitus: A systematic review and meta-analysis

AIMS

A systematic review and meta-analysis of published randomized controlled trials was conducted to collate evidence from studies implementing ancient grains and investigate the impact of ancient grain consumption on health outcomes of patients with Diabetes Mellitus (DM).

DATA SYNTHESIS

Twenty-nine randomized controlled trials were included, and 13 were meta-analyzed. Interventions ranged from 1 day to 24 weeks; most samples were affected by DM type 2 (n = 28 studies) and the ancient grains used were oats (n = 10 studies), brown rice (n = 6 studies), buckwheat (n = 4 studies), chia (n = 3 studies), Job's Tears (n = 2 studies), and barley, Khorasan and millet (n = 1 study). Thirteen studies that used oats, brown rice, and chia provided data for a quantitative synthesis. Four studies using oats showed a small to moderate beneficial effect on health outcomes including LDL-c (n = 717, MD: 0.30 mmol/l, 95% CI: 0.42 to -0.17, Z = 4.61, p < 0.05, I2 = 0%), and TC (n = 717, MD: 0.44 mmol/l, 95% CI: 0.63 to -0.24, Z = 4.40, p < 0.05, I2 = 0%). Pooled analyses of studies using chia and millet did not show significant effects on selected outcomes.

CONCLUSIONS

For adults affected by DM type 2, the use of oats may improve lipidic profile. Further experimental designs are needed in interventional research to better understand the effects of ancient grains on diabetes health outcomes.

PROSPERO REGISTRATION

CRD42023422386.

Advancements in Nutritional Strategies for Gestational Diabetes Management: A Systematic Review of Recent Evidence

Gestational diabetes mellitus (GDM) is defined as hyperglycaemia first detected at any time during pregnancy with values lower than those determined by the WHO for diabetes diagnosis in adults. This pathology, with a worldwide prevalence of 13.4%, causes significant maternal and foetal risks. The first line of treatment consists of maintaining normo-glycaemia through an adequate diet and lifestyle changes. The aim is to synthesize the scientific evidence updating the nutritional recommendations for the effective management of GDM. A systematic review of the scientific literature was conducted following the PRISMA guidelines. Randomized clinical trials published within the last five years and providing information on nutritional recommendations to achieve an effective management of gestational diabetes were selected. The databases searched were PubMed, the WOS Core Collection, SCOPUS, and CINAHL, using the MeSH terms: "Diabetes, Gestational"; "Nutrition Assessment (nutrition*)"; "Diet"; "Eating"; and "Food"; with the Boolean operators "AND" and "OR". The PEDro scale (Physiotherapy Evidence Database) was used to assess the scientific quality of the studies, with a mean score of 8.9, indicating an average good scientific quality. Results: A total of 809 papers were collected, of which, after applying the inclusion and exclusion criteria, 14 randomized clinical trials were selected. Probiotic supplementation and co-supplementation with vitamin D have been found to be the most beneficial options for both mothers with GDM and neonates, but the most effective regimens are not known. Diets enriched with extra virgin olive oil (EVOO) and oat bran, as well as some recommendations focused on carbohydrates also seem effective, as well as diets designed for this group of women with GDM such as "CHOICE". Conclusions: Although there are numerous proposals that have been published in recent years focused on the diet of women with GDM in order to improve their results and those of their children, it is the supplementation with probiotics and the co-supplementation with vitamin D that is most agreed upon as beneficial; however, more research is needed into which protocols are most effective. Other proposals that could also be beneficial should be further studied.

Effect of viscous soluble dietary fiber on glucose and lipid metabolism in patients with type 2 diabetes mellitus: a systematic review and meta-analysis on randomized clinical trials

Background

The effect of viscous soluble dietary fiber on glucose and lipid metabolism in type 2 diabetes mellitus (T2DM) remains controversial, and the dose-response relationship of its effect on blood glucose and blood lipid level is still unclear.

Methods

We conducted comprehensive searches in several databases up to 17 January 2023. We conducted a dose-response analysis of randomized controlled trials (RCTs) to investigate the effect of viscous dietary fiber on glucose and lipid metabolism in patients with T2DM.

Results

Statistical significance was observed in the decreases of glycosylated hemoglobin (HbA1c) (mean difference) [MD = -0.47; 95%CI: (-0.66, -0.27)], fasting blood glucose (FBG) [MD = -0.93; 95%CI: (-1.46, -0.41)], total cholesterol (TC) [MD = -0.33; 95%CI: (-0.46, -0.21)], and low-density lipoprotein and cholesterol (LDL-C) [MD = -0.24; 95%CI: (-0.35, -0.13)]. Contrarily, no difference was observed regarding the level of high-density lipoprotein cholesterol (HDL-C) or triglyceride (TG). In addition, the effect on fasting insulin remains unclear. Results from the subgroup analyses showed that an intervention duration longer than 6 weeks had a significant effect on the HbA1c level; a treatment dosage higher than 8.3 g/day had a significant effect on the FBG level.

Conclusions

Supplementation of viscous dietary fiber is beneficial to control blood glucose and blood lipid in T2DM.

Effect of Oat (Avena sativa L.) Consumption on Lipid Profile With Focus on Triglycerides and High-density Lipoprotein Cholesterol (HDL-C): An Updated Systematic Review

Hypercholesterolemia is a significant risk factor for heart disease. The soluble fiber in oat (Avena sativa L.), beta-glucan has been shown to significantly lower serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels but not triglycerides (TG) and high-density lipoprotein cholesterol (HDL-C) according to previous studies, reviews, and meta-analyses. However, the effect of oat consumption on the TG and HDL-C is controversial and has not been expanded enough. We did this review study to find out about the effect of oat on lipid profile especially TG and HDL-C more specifically and meticulously with their details. After searching PubMed, Web of Science, and Google scholar we included 17 studies in our review. Our results similar to other reviews showed that oat reduced the TC, VLDL, and LDL-C more significantly than TG. Of 17 included studies 6 studies reported reduction of TG level, and only 1 study reported HDL-C improvement followed by oat consumption. A more detailed review of studies that reported positive effects of oat/ beta-glucan consumption on TG showed that in healthy people with normal lipid profile oat intake might reduce TG effectively and also in overweight people/those with diabetes or metabolic syndrome if a higher amount of oat or/and longer duration applied. Consuming oat in conjunction with calorie-reducing diets or using it with DHA can cause a significant TG reduction. It may be concluded that, in addition to lowering TC and LDL-C, a considerable improvement in TG or HDL-C can be accomplished by adjusting factors such as oat consumption dose or consumption duration or utilizing oat in conjunction with a proper diet program. To conclude, more research on this topic is required.

Dietary Supplements Containing Oat Beta-Glucan and/or Green Coffee (Poly)phenols Showed Limited Effect in Modulating Cardiometabolic Risk Biomarkers in Overweight/Obese Patients without a Lifestyle Intervention

Obesity has reached pandemic proportions and has become a major health concern worldwide. Therefore, it is necessary to find new strategies against this condition and its associated comorbidities. Green coffee polyphenols (GCP) and oat beta-glucans (BGs) have proven their hypolipidaemic and hypoglycaemic effects. This study aimed to examine the effects of the long-term consumption of supplements containing GCP, BG or the novel GCP/BG combination on lipid and glucose metabolism biomarkers in overweight/obese subjects who maintained their dietary habits and physical activity, hence addressing the difficulty that this population faces in adapting to lifestyle changes. A randomised, crossover, blind trial was carried out in 29 volunteers who consumed either GCP (300 mg), BG (2.5 g) or GCP/BG (300 mg + 2.5 g) twice a day for 8 weeks. Blood samples were collected, and blood pressure and body composition were measured at the beginning and end of each intervention. Total cholesterol, triglycerides, high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C), very low-density lipoprotein (VLDL-C) cholesterol, glycated haemoglobin, fasting glucose, insulin, aspartate transaminase, alanine transaminase and different hormones and adipokines were analysed. Only VLDL-C (p = 0.01) and diastolic blood pressure (p = 0.027) decreased after the intervention, especially with the BG supplement. There were no other significant changes in the analysed biomarkers. In conclusion, the regular intake of GCP, BG and GCP/BG without lifestyle changes is not an efficient strategy to improve lipid and glucose homeostasis in overweight/obese subjects.

Effects of a lifestyle intervention on the biomarkers of oxidative stress in non-communicable diseases: A systematic review

Oxidative stress plays a critical role in the pathogenesis of chronic diseases. Therefore, improvement of oxidative stress status through lifestyle intervention can play a vital role in preventing and treating chronic diseases. This systematic review aims to provide an overview of articles published in the last decade examining the association between lifestyle intervention and oxidative stress biomarkers in the context of non-communicable diseases. The electronic databases PubMed and Web of Science were searched for relevant studies, following the PRISMA (Preferred Reporting of Systematic Reviews and Meta-Analyses) guidelines. This systematic review focused on the four important oxidative stress biomarkers; glutathione (GSH), superoxide dismutase (SOD), catalase, and malondialdehyde. 671 articles were identified, of which nine met the inclusion criteria. A trend emerged, showing that lifestyle modifications that focus on diet and physical health can improve oxidative stress in the form of an increase in superoxide dismutase and CAT levels and a decrease in Malondialdehyde levels in participants with non-communicable diseases (NCDs), GSH levels were not affected. However, the results are difficult to compare because of the heterogeneity of the methods of the biomarkers studied. Our review indicates that oxidative stress can be influenced by lifestyle modifications and may be an effective tool for the prevention and management of non-communicable diseases. This review also elucidated the importance of analyzing multiple oxidative stress biomarkers to evaluate oxidative stress, it further highlights the need to conduct long-term lifestyle intervention studies on oxidative stress biomarkers to understand the connection between oxidative stress biomarkers, NCDs and Lifestyle intervention.

Chronic consumption of probiotics, oats, and apples has differential effects on postprandial bile acid profile and cardiometabolic disease risk markers compared with an isocaloric control (cornflakes): a randomized trial

BACKGROUND

Dietary components that impact the gut microbiota may beneficially affect cardiometabolic health, possibly by altered bile acid metabolism. However, impacts of these foods on postprandial bile acids, gut microbiota, and cardiometabolic risk markers are unclear.

OBJECTIVES

The aim of this study was to determine the chronic effects of probiotics, oats, and apples on postprandial bile acids, gut microbiota, and cardiometabolic health biomarkers.

METHODS

Using an acute within chronic parallel design, 61 volunteers (mean ± SD: age 52 ± 12 y; BMI 24.8 ± 3.4 kg/m²) were randomly assigned to consume 40 g cornflakes (control), 40 g oats or 2 Renetta Canada apples each with 2 placebo capsules per day or 40 g cornflakes with 2 Lactobacillus reuteri capsules (>5 × 10⁹ CFU) per day, for 8 wk. Fasting and postprandial serum/plasma bile acids and cardiometabolic health biomarkers, fecal bile acids, and gut microbiota composition were determined.

RESULTS

At week 0, oats and apples significantly decreased postprandial serum insulin [area under the curve (AUC): 25.6 (17.4, 33.8) and 23.4 (15.4, 31.4) vs. 42.0 (33.7, 50.2) pmol/L × min and incremental AUC (iAUC): 17.8 (11.6, 24.0) and 13.7 (7.7, 19.8) vs. 29.6 (23.3, 35.8) pmol/L × min] and C-peptide responses [AUC: 599 (514, 684) and 550 (467, 632) vs. 750 (665, 835) ng/mL × min], whereas non-esterified fatty acids were increased [AUC 135 (117, 153) vs. 86.3 (67.9, 105) and iAUC 96.2 (78.8, 114) vs. 60 (42.1, 77.9) mmol/L × min] after the apples vs. control (P ≤ 0.05). Postprandial unconjugated [AUC: predicted means (95% CI) 1469 (1101, 1837) vs. 363 (-28, 754) μmol/L × min and iAUC: 923 (682, 1165) vs. 22.0 (-235, 279) μmol/L × min)] and hydrophobic [iAUC: 1210 (911, 1510) vs. 487 (168, 806) μmol/L × min] bile acid responses were increased after 8 wk probiotic intervention vs. control (P ≤ 0.049). None of the interventions modulated the gut microbiota.

CONCLUSIONS

These results support beneficial effects of apples and oats on postprandial glycemia and the ability of the probiotic Lactobacillus reuteri to modulate postprandial plasma bile acid profiles compared with control (cornflakes), with no relationship evident between circulating bile acids and cardiometabolic health biomarkers.

Effect of oats and oat ß-glucan on glycemic control in diabetes: a systematic review and meta-analysis of randomized controlled trials

Introduction

Current health claims recognize the ability of oat ß-glucan to lower blood cholesterol; however, its ability to improve glycemic control is less certain. We undertook a systematic review and meta-analysis of randomized controlled trials (RCTs) to update the evidence on the effect of oats and oat ß-glucan on glycemic control in individuals with diabetes.

Research design and methods

MEDLINE, EMBASE and Cochrane were searched (June 2021) for RCTs of ≥2 weeks investigating the effect of oat ß-glucan on glycemic control in diabetes. The outcomes were hemoglobin A1c (HbA1c), fasting glucose, 2-hour postprandial glucose (2h-PG) from a 75 g oral glucose tolerance test, homeostatic model assessment of insulin resistance (HOMA-IR) and fasting insulin. Independent reviewers extracted the data and assessed the risk of bias. Data were pooled using the generic inverse variance method. Heterogeneity was assessed (Cochran Q) and quantified (I2). Pooled estimates were expressed as mean difference (MD) with 95% CI. The certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluations approach.

Results

Eight trial comparisons (n=407) met the eligibility criteria. All trials were in adults with type 2 diabetes who were predominantly middle-aged, overweight and treated by antihyperglycemic medications or insulin. A median dose of 3.25 g of oat ß-glucan for a median duration of 4.5 weeks improved HbA1c (MD, −0.47% (95% CI −0.80 to −0.13), pMD=0.006), fasting glucose (−0.75 mmol/L (−1.20 to –0.31), pMD<0.001), 2h-PG (−0.42 mmol/L (−0.70 to –0.14), pMD=0.003) and HOMA-IR (−0.88 (−1.55 to –0.20), pMD=0.011). There was a non-significant reduction in fasting insulin (−4.30 pmol/L (−11.96 to 3.35), pMD=0.271). The certainty of evidence was high for fasting glucose, moderate for HOMA-IR and fasting insulin (downgraded for imprecision), and low for HbA1c and 2h-PG (downgraded for imprecision and inconsistency).

Conclusions

Consumption of oats and oat ß-glucan results in generally small improvements in established markers of fasting and postprandial glycemic control beyond concurrent therapy in adults with type 2 diabetes. The current evidence provides a very good indication for reductions in fasting glucose and less of an indication for reductions in HbA1c, 2h-PG, fasting insulin and HOMA-IR in this population.

Trial registration number

NCT04631913.

Role of Whole Grain Consumption in Glycaemic Control of Diabetic Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Observational studies have indicated beneficial effects of whole grain consumption on human health. However, no evidence based on randomized controlled trials has been established. Our objective was to perform a systematic review and meta-analysis of randomized controlled trials to assess the effects of whole grain consumption in glycaemic control of diabetic patients. Methods: A comprehensive search in four databases (Web of Science, Pubmed, Scopus and Cochrane library) was conducted to collect potential articles which measured the roles of whole grain consumption on glycaemic control up to October 2021. Results: A total of 16 eligible trials involving 1068 subjects were identified to evaluate the pooled effect. The overall results indicated that compared with the control group, whole grain intake presented a significantly reduced concentration in fast plasma glucose (WMD = −0.51 mmol/L, 95% CI: −0.73, −0.28; I2 = 88.6%, p < 0.001), a homeostasis model assessment of insulin resistance (WMD = −0.39 μU × mol/L², 95% CI: −0.73, −0.04; I2 = 58.4%, p = 0.014), and glycosylated haemoglobin (WMD = −0.56%, 95% CI: −0.88, −0.25, I2 = 88.5%, p < 0.001), while no significant difference was observed in fast plasma insulin level between groups (SMD = −0.05, 95% CI: −0.25, 0.14; I2 = 40.7%, p = 0.120). In terms of incremental area under the curve (iAUC), data suggested that whole grain effected a significant decrease in Glucose-iAUC (WMD = −233.09 min × mmol/L, 95% CI: −451.62, −14.57; I2 = 96.1%, p < 0.001) and Insulin-iAUC (SMD = −4.80, 95% CI: −8.36, −1.23; I2 = 89.9%, p = 0.002), although only in a small number of studies. Of note, there is evidence for modest unexplained heterogeneity in the present meta-analysis. Conclusion: Whole grain consumption confers a beneficial effect on glucose metabolism in patients with diabetes. Regrettably, since relevant studies were scarce, we failed to provide confident evidence of whole grain consumption on acute effects including Glucose-iAUC and Insulin-iAUC, which should be addressed in further trials.

Effects of Oats (Avena sativa L.) on Inflammation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Oat and its compounds have been found to have anti-inflammatory effects. Through this systematic review and meta-analysis, we aimed to determine an evidence-based link between oat consumption and inflammatory markers. Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. By the end of April 2021, we included randomized controlled trials (RCTs) that investigated the anti-inflammatory effect of oat and oat-related products through screening PubMed, Embase, Web of Science, ClinicalTrial.gov, and CENTRAL. Meta-analysis was conducted with a random-effect model on the standardized mean difference (SMD) of the change scores of inflammatory markers, including C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-8 (IL-8). Subgroup analyses were conducted to stratify confounding variables. The risk of bias was evaluated using the Cochrane risk of bias tool and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was applied to report the quality of evidence. This study was registered in the International Prospective Register of Systematic Reviews (PROSPERO; CRD42021245844). Results: Systematic screening of five databases yielded 4,119 studies, of which 23 RCTs were finally selected. For the four systemic inflammatory markers analyzed, no significant alterations were found after oat consumption. However, oat intake was found to significantly decrease CRP levels in subjects with one or more health complications (SMD: -0.18; 95% CI: -0.36, 0.00; P = 0.05; I ² = 10%). Furthermore, IL-6 levels were significantly decreased in subjects with dyslipidemia (SMD = -0.34; 95% CI: -0.59, -0.10; P = 0.006; I ² = 0%). These beneficial effects might be attributed to the effects of avenanthramide and β-glucan. Conclusions: Overall evidence supporting the alleviation of inflammatory response by oat intake was poor, calling for future studies including a larger sample size to confirm the findings.

An Oat β-Glucan Beverage Reduces LDL Cholesterol and Cardiovascular Disease Risk in Men and Women with Borderline High Cholesterol: A Double-Blind, Randomized, Controlled Clinical Trial

BACKGROUND

High-molecular-weight (MW) oat β-glucan (OBG), consumed at 3-4 g/d, in solid foods reduces LDL cholesterol by a median of ∼6.5%.

OBJECTIVES

We evaluated the effect of a beverage providing 3 g/d high-MW OBG on reduction of LDL cholesterol (primary endpoint) when compared with placebo.

METHODS

We performed a parallel-design, randomized clinical trial at a contract research organization; participants, caregivers, and outcome assessors were blinded to treatment allocation. Participants with LDL cholesterol between 3.0 and 5.0 mmol/L, inclusive [n = 538 screened, n = 260 ineligible, n = 23 lost, n = 48 withdrawn (product safety); n = 207 randomly assigned, n = 7 dropped out, n = 9 withdrawn (protocol violation); n = 191 analyzed; n = 72 (37.7%) male, mean ± SD age: 43.3 ± 14.3 y, BMI: 29.7 ± 5.2 kg/m2], were randomly assigned to consume, 3 times daily for 4 wk, 1 g OBG (n = 104, n = 96 analyzed) or rice powder (Control, n = 103, n = 95 analyzed) mixed into 250 mL water. Treatment effects were assessed as change from baseline and differences analyzed using a 2-sided t test via ANOVA with baseline characteristics as covariates.

RESULTS

After 4 wk, change from baseline least-squares-mean LDL cholesterol on OBG (-0.195 mmol/L) was less than on Control (0.012 mmol/L) by mean: 0.207 mmol/L (95% CI: 0.318, 0.096 mmol/L; P = 0.0003); the following secondary endpoints were also reduced as follows: total cholesterol (TC) (0.226 mmol/L; 95% CI: 0.361, 0.091 mmol/L; P = 0.001), TC:HDL cholesterol ratio (0.147; 95% CI: 0.284, 0.010; P = 0.036), non-HDL cholesterol (0.194 mmol/L; 95% CI: 0.314, 0.073 mmol/L; P = 0.002), and Framingham cardiovascular disease (CVD) risk (0.474; 95% CI: 0.900, 0.049, P = 0.029). Changes in HDL cholesterol, triglycerides, glucose, and insulin did not differ between treatment groups (P > 0.05). Lipid treatment effects were not significantly modified by age, sex, BMI, or hypertension treatment. There were no major adverse events, but both treatments transiently increased gastrointestinal symptoms.

CONCLUSIONS

Consuming a beverage containing 1 g high-MW OBG 3 times daily for 4 wk significantly reduced LDL cholesterol by ∼6% and CVD risk by ∼8% in healthy adults with LDL cholesterol between 3 and 5 mmol/L.This trial was registered at clinicaltrials.gov as NCT03911427.

Application of metabolomics for revealing the interventional effects of functional foods on metabolic diseases

Metabolomics is an important branch of systems biology, which can detect changes in the body's metabolism before and after the intervention of functional foods, identify effective metabolites, and predict the interventional effects and the mechanism. This review summarizes the latest research outcomes regarding interventional effects of functional foods on metabolic diseases via metabolomics analysis. Since metabolomics approaches are powerful strategies for revealing the changes in bioactive compounds of functional foods during processing and storage, we also discussed the effects of these parameters on functional food metabolites using metabolomics approaches. To date, a number of endogenous metabolites related to the metabolic diseases after functional foods intervention have been discovered. Unfortunately, the mechanisms of metabolic disease-related molecules are still unclear and require further studies. The combination of metabolomics with other omics technologies could further promote its ability to fully understand the precise biological processes of functional food intervention on metabolic diseases.

Oat Intake and Risk of Type 2 Diabetes, Cardiovascular Disease and All-Cause Mortality: A Systematic Review and Meta-Analysis

Cardiovascular disease (CVD) and type 2 diabetes (T2D) remain the top disease and mortality burdens worldwide. Oats have been shown to benefit cardiovascular health and improve insulin resistance. However, the evidence linking oat consumption with CVD, T2D and all-cause mortality remains inconclusive. We conducted a comprehensive systematic review and meta-analysis of prospective cohort studies to evaluate the associations between oat consumption and risks of T2D, CVD and all-cause mortality in the general population. Five electronic databases were searched until September, 2020. Study specific relative risks (RR) were meta-analyzed using random effect models. Of 4686 relevant references, we included 9 articles, based on 8 unique studies and 471,157 participants. Comparing oat consumers versus non-consumers, RRs were 0.86 (95% CI 0.72–1.03) for T2D incidence and 0.73 (95% CI 0.5–1.07) for combined CVD incidence. Comparing participants with highest versus lowest oat intake, RRs were 0.78 (95% CI 0.74–0.82) for T2D incidence, 0.81 (95% CI 0.61–1.08) for CHD incidence and 0.79 (95% CI 0.59–1.07) for stroke. For all-cause mortality one study based on three cohorts found RR for men and women were 0.76 (95% CI 0.69–0.85) and 0.78 (95% CI 0.70–0.87), respectively. Most studies (n = 6) were of fair to good quality. This meta-analysis suggests that consumption of oat could reduce the risk for T2D and all-cause mortality, while no significant association was found for CVD. Future studies should address a lack of standardized methods in assessing overall oat intake and type of oat products, and investigate a dose-dependent response of oat products on cardiometabolic outcomes in order to introduce oat as preventive and treatment options for the public.

Association between Dietary Inflammatory Index and Type 2 diabetes mellitus in Xinjiang Uyghur autonomous region, China

Background

Diet and inflammation have both been studied in relation to type 2 diabetes mellitus (T2DM). The aim of this cross-sectional study was to examine the association between the Dietary Inflammatory Index (DII®) and T2DM.

Methods

Subjects were adults enrolled in the baseline study of the Xinjiang multi-ethnic natural population cohort and health follow-up study from January to May 2019. The study involved 5,105 subjects (58.7% men) between 35 and 74 years of age. The DII score was calculated from a data obtained via a food frequency questionnaire consisting of 127 food items.

Results

Logistic regression analyses were used to estimate the odds ratios (ORs) and 95% confidence intervals (95% CIs) of DII in relation to T2DM. After adjusting for potential confounders, compared to subjects in the 1st DII quintile, subjects in the 5th quintile (i.e., with the most pro-inflammatory diet) had higher odds of T2DM (OR = 3.27, 95%CI:2.38,4.50; p < 0.001).

Conclusions

Our results suggest that a pro-inflammatory diet is associated with a higher risk of T2DM in this population of Chinese adults.

The effect of oat bran consumption on gestational diabetes: a randomized controlled clinical trial

BACKGROUND

Gestational diabetes is the most common medical complication in pregnancy, and it has many side effects for the mother and the fetus. The aim of this study was to evaluate the effect of oat bran consumption on gestational diabetes.

METHODS

This study is a randomized clinical trial that was performed on 112 women with gestational diabetes treated with diet. Participants were randomly divided into two groups of 56. Participants in both groups were given a diet for gestational diabetes. In addition to the diet, the intervention group received 30 g of oat bran daily for 4 weeks at lunch and dinner. Tests of fasting blood glucose and two-hour postprandial (2hpp) glucose were taken from both groups: before the intervention, and 2 and 4 weeks after the start of the intervention. Data analysis was performed using SPSS statistical software (version 22) using independent t-test, as well as Chi-square and Mann-Whitney tests. P values less than 0.05 were considered statistically significant.

RESULTS

There was no statistically significant difference between the two groups in terms of mean blood glucose before the intervention, while 2 and 4 weeks after the intervention, mean fasting blood glucose and two-hour postprandial (2hpp) glucose decreased significantly in the intervention group compared with the control group (P < 0.001).

CONCLUSION

Based on the results of this study, the addition of oat bran to the standard diet for pregnant women with gestational diabetes reduced fasting blood glucose and two-hour postprandial (2hpp) glucose. More detailed studies with higher sample sizes are recommended to prove the effectiveness of this valuable dietary supplement.

TRIAL REGISTRATION

IRCT registration number: IRCT20191220045828N1 . Registration date: 2020-04-18. Registered while recruiting.

Global review of heart health claims for oat beta-glucan products

Coronary heart disease (CHD) is the leading cause of death globally. Consumption of whole grains and cereal fiber, as part of a healthy diet, can lower the risk of CHD. Health claims on food products are effective in helping consumers select healthful diets. The US Food and Drug Administration was the first to approve a health claim, in 1997, between beta-glucan soluble fiber from whole oats, oat bran, and whole oat flour and reduced risk of CHD. Only a few countries have approved similar claims. Since 1997, a significant amount of additional evidence has been published on the relationship between oat beta-glucan and CHD. To assist other jurisdictions in potentially utilizing this claim, the full extent of data that supports this claim (ie, the evidence utilized by the US Food and Drug Administration to substantiate the claim, as well as the results of 49 clinical trials published since 1997) are reviewed here. The complexities involved in authoring evidence-based health claims, including the impact of processing on beta-glucan cholesterol-lowering efficacy in approving eligible beta-glucan products, are also discussed.

Effects of soluble fiber supplementation on glycemic control in adults with type 2 diabetes mellitus: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND & AIMS

Soluble dietary fiber is prompted as an important part of reducing blood glucose, ameliorating insulin resistance and controlling body weight. Thus, we performed this systematic review and meta-analysis of randomized controlled trials (RCTs) to quantify and synthesize the effects of soluble fiber supplementation on glycemic control and BMI modification in adults with type 2 diabetes.

METHODS

We searched MEDLINE, Embase, Web of Science, ClinicalTrials.gov, and Cochrane databases until February 13, 2020 to identify RCTs that detected the effects of soluble fiber supplementation on glycemic control in adults with type 2 diabetes. A random-effects model with the generic inverse variance method was used to analyze the pooled data. The meta-regression and subgroup analyses were conducted to identify the variables that influenced the pooled results. The robust error meta-regression model was used to conduct the dose-response test. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system was undertaken to evaluate the overall quality of the evidence.

RESULTS

A total of 29 RCTs (33 comparisons) involving 1517 participants were identified in this meta-analysis. Results showed that supplemental soluble dietary fiber significantly reduced glycosylated hemoglobin (HbA1c, MD -0.63%, 95% CI [-0.90, -0.37]; P < 0.00001), fasting plasma glucose (FPG, MD -0.89 mmol/L, 95% CI [-1.28, -0.51]; P < 0.00001), fasting insulin (SMD -0.48, 95% CI [-0.80, -0.17]; P = 0.003), homeostatic model assessment of insulin resistance (HOMA-IR, SMD -0.58, 95% CI [-0.86, -0.29], P < 0.0001), fructosamine (SMD -1.03, 95% CI [-1.51, -0.55]; P < 0.0001), 2-h postprandial plasma glucose (SMD -0.74, 95% CI [-1.00, -0.48]; P < 0.00001), and BMI (SMD -0.31, 95% CI [-0.61, -0.00], P = 0.05) compared with control diets in patients with type 2 diabetes. Specifically, dose-response meta-analyses presented that a daily dosage of 7.6-8.3 g was recommended.

CONCLUSION

Intake of soluble fiber supplementation is effective in improving glycemic control and BMI level in type 2 diabetes and is also a convenient way to help individuals meet standard dietary fiber needs. But due to the evidence of substantial heterogeneity in most pooled estimates, further long-term and high-quality RCTs are needed.

Post-transplantation plasma malondialdehyde is associated with cardiovascular mortality in renal transplant recipients: a prospective cohort study

BACKGROUND

In renal transplant recipients (RTRs), cardiovascular mortality is the most common cause of long-term renal graft loss. Oxidative stress (OS) has been associated with cardiovascular disease and is known to be enhanced in RTRs. We aimed to prospectively investigate whether the concentration of the OS biomarker malondialdehyde (MDA) is associated with long-term risk of cardiovascular mortality in a large cohort of RTRs.

METHODS

The plasma MDA concentration was measured using the thiobarbituric acid reaction assay in 604 extensively phenotyped RTRs with a functioning allograft for ≥1 year. The association between MDA and cardiovascular mortality was assessed using Cox proportional hazard regression analyses in the overall cohort and within subgroups according to significant effect modifiers.

RESULTS

Median circulating MDA concentration at baseline was 5.38 [interquartile range (IQR) 4.31-6.45] μmol/L. During a follow-up period of 6.4 (IQR 5.6-6.8) years, 110 (18%) RTRs died, with 40% of deaths due to cardiovascular causes. MDA concentration was significantly associated with the risk for cardiovascular mortality {hazard ratio [HR] 1.31 [95% confidence interval (CI) 1.03-1.67] per 1-SD increment}, independent of adjustment for potential confounders, including renal function, immunosuppressive therapy, smoking status and blood pressure. The association between MDA concentration and the risk for cardiovascular mortality was stronger in RTRs with relatively lower plasma ascorbic acid concentrations [≤42.5 µmol/L; HR 1.79 (95% CI 1.30-2.48) per 1-SD increment] or relatively lower estimated glomerular filtration rates [≤45 mL/min/1.73 m2; HR 2.09 (95% CI 1.45-3.00) per 1-SD increment].

CONCLUSIONS

Circulating MDA concentration is independently associated with long-term risk for cardiovascular mortality, particularly in RTRs with relatively lower ascorbic acid concentrations or renal function. Further studies are warranted to elucidate whether OS-targeted interventions could decrease cardiovascular mortality in RTRs.

The Metabolic Concept of Meal Sequence vs. Satiety: Glycemic and Oxidative Responses with Reference to Inflammation Risk, Protective Principles and Mediterranean Diet

With increasing exposure to eating opportunities and postprandial conditions becoming dominant states, acute effects of meals are garnering interest. In this narrative review, meal components, combinations and course sequence were questioned vis-à-vis resultant postprandial responses, including satiety, glycemic, oxidative and inflammatory risks/outcomes vs. protective principles, with reference to the Mediterranean diet. Representative scientific literature was reviewed and explained, and corresponding recommendations discussed and illustrated. Starting meals with foods, courses and/or preloads high in innate/added/incorporated water and/or fibre, followed by protein-based courses, delaying carbohydrates and fatty foods and minimizing highly-processed/sweetened hedonic foods, would increase satiety-per-calorie vs. obesogenic passive overconsumption. Similarly, starting with high-water/fibre dishes, followed by high-protein foods, oils/fats, and delayed/reduced slowly-digested whole/complex carbohydrate sources, optionally closing with simpler carbohydrates/sugars, would reduce glycaemic response. Likewise, starting with foods high in innate/added/incorporated water/fibre/antioxidants, high monounsaturated fatty acid foods/oils, light proteins and whole/complex carbohydrate foods, with foods/oils low in n-6 polyunsaturated fatty acids (PUFA) and n-6:n-3 PUFA ratios, and minimal-to-no red meat and highly/ultra-processed foods/lipids, would reduce oxidative/inflammatory response. Pyramids illustrating representative meal sequences, from most-to-least protective foods, visually communicate similarities between axes, suggesting potential unification for optimal meal sequence, consistent with anti-inflammatory nutrition and Mediterranean diet/meal principles, warranting application and outcome evaluation.

Nutritional strategies in managing postmeal glucose for type 2 diabetes: A narrative review

Medical Nutrition Therapy (MNT) plays an essential role in overall glycemic management. Less focus is given on managing postmeal hyperglycemia despite the facts that, it is a common feature of Type 2 Diabetes (T2D). The purpose of this narrative review is to provide a comprehensive understanding of the existing literature on the nutritional approaches to improve postmeal hyperglycemia in patients with T2D. We searched multiple databases for the studies examining the nutritional approaches to manage postmeal glucose in patients with T2D. We included studies that involve human trials that were published in English for the past 10 years. Our review of the current literature indicates that the postmeal hyperglycemia can be improved with four nutritional approaches. These approaches include (i) utilizing the appropriate amount and selecting the right type of carbohydrates, (ii) using specific types of dietary protein, (iii) manipulating the meal timing and orders and (iv) others (promoting postmeal physical activity, incorporating diabetes-specific formula and certain functional foods). The potential mechanisms underlying these approaches are discussed and the identified gaps warranted further research. This array of nutritional strategies provide a set of options for healthcare professionals to facilitate patients with T2D in achieving the optimal level of postmeal glucose.

Should Viscous Fiber Supplements Be Considered in Diabetes Control? Results From a Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE

Evidence from randomized controlled trials (RCTs) suggests that viscous dietary fiber may offer beneficial effects on glycemic control and, thus, an improved cardiovascular disease risk profile. Our purpose was to conduct a systematic review and meta-analysis of RCTs to synthesize the therapeutic effect of viscous fiber supplementation on glycemic control in type 2 diabetes.

RESEARCH DESIGN AND METHODS

MEDLINE, Embase, and Cochrane Central Register of Controlled Trials were searched through 15 June 2018. We included RCTs ≥3 weeks in duration that assessed the effects of viscous fiber on markers of glycemic control in type 2 diabetes. Two independent reviewers extracted data. Data were pooled using the generic inverse variance method and expressed as mean differences (MD) with 95% CIs. Heterogeneity was assessed (Cochran Q statistic) and quantified (I ² statistic). The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to evaluate the overall certainty of the evidence.

RESULTS

We identified 28 eligible trial comparisons (n = 1,394). Viscous fiber at a median dose of ∼13.1 g/day significantly reduced HbA_1c (MD -0.58% [95% CI -0.88, -0.28]; P = 0.0002), fasting blood glucose (MD -0.82 mmol/L [95% CI -1.32, -0.31]; P = 0.001), and HOMA-insulin resistance (IR) (MD -1.89 [95% CI -3.45, -0.33]; P = 0.02) compared with control and in addition to standard of care. The certainty of evidence was graded moderate for HbA_1c, fasting glucose, fasting insulin, and HOMA-IR and low for fructosamine.

CONCLUSIONS

Viscous fiber supplements improve conventional markers of glycemic control beyond usual care and should be considered in the management of type 2 diabetes.

Dietary Fiber Intake and Type 2 Diabetes Mellitus: An Umbrella Review of Meta-analyses

Objective

The purpose of this study was to review previously published meta-analyses on the effectiveness of dietary fiber on type 2 diabetes.

Methods

An umbrella review of all published meta-analyses was performed. A PubMed search from January 1, 1980, to April 30, 2017, was conducted using the following search strategy: (fiber OR glucan OR psyllium) AND (meta-analysis OR systematic review). Only English-language publications that provided quantitative statistical analysis on type 2 diabetes, fasting blood glucose concentrations, or glycosylated hemoglobin were retrieved.

Results

Sixteen meta-analyses were retrieved for inclusion in this umbrella review. In the meta-analyses comparing highest versus lowest dietary fiber intake, there was a statistically significant reduction in the relative risk (RR) of type 2 diabetes (RR = 0.81-0.85), with the greatest benefit coming from cereal fibers (RR = 0.67-0.87). However, statistically significant heterogeneity was observed in all of these meta-analyses. In the meta-analyses of supplementation studies using β-glucan or psyllium fibers on type 2 diabetic participants, statistically significant reductions were identified in both fasting blood glucose concentrations and glycosylated hemoglobin percentages.

Conclusion

This review suggests that those consuming the highest amounts of dietary fiber, especially cereal fiber, may benefit from a reduction in the incidence of developing type 2 diabetes. There also appears to be a small reduction in fasting blood glucose concentration, as well as a small reduction in glycosylated hemoglobin percentage for individuals with type 2 diabetes who add β-glucan or psyllium to their daily dietary intake.

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.

The difference between oats and beta-glucan extract intake in the management of HbA1c, fasting glucose and insulin sensitivity: a meta-analysis of randomized controlled trials

Increasing oats and beta-glucan extract intake has been associated with improved glycemic control, which is associated with the reduction in the development of diabetes. This study aims to assess the different effects between oat (whole and bran) and beta-glucan extract intake on glycemic control and insulin sensitivity. PubMed, Embase, Medline, The Cochrane Library, CINAHL and Web of Science were searched up to February 2014. We included randomized controlled trials with interventions that lasted at least four weeks that compared oats and beta-glucan (extracted from oats or other sources) intake with a control. A total of 1351 articles were screened for eligibility, and relevant data were extracted from 18 studies (n = 1024). Oat product dose ranged from 20 g d(-1) to 136 g d(-1), and beta-glucan extract dose ranged from 3 g d(-1) to 10 g d(-1). Compared with the control, oat intake resulted in a greater decrease in fasting glucose and insulin of subjects (P < 0.05), but beta-glucan extract intake did not. Furthermore, oat intake resulted in a greater decrease in glycosylated hemoglobin (HbA1c) (P < 0.001, I(2) = 0%) and fasting glucose (P < 0.001, I(2) = 68%) after removing one study using a concentrate and a different design and fasting insulin of type 2 diabetes (T2D) (P < 0.001, I(2) = 0%). The intake of oats and beta-glucan extracted from oats were effective in decreasing fasting glucose (P = 0.007, I(2) = 91%) and fasting insulin of T2D (P < 0.001, I(2) = 0%) and tented to lower HbA1c (P = 0.09, I(2) = 92%). Higher consumption of whole oats and oat bran, but not oat or barley beta-glucan extracts, are associated with lower HbA1c, fasting glucose and fasting insulin of T2D, hyperlipidaemic and overweight subjects, especially people with T2D, which supports the need for clinical trials to evaluate the potential role of oats in approaching to the management of glycemic control and insulin sensitivity of diabetes or metabolic syndrome subjects.

The effect of oat β-glucan on LDL-cholesterol, non-HDL-cholesterol and apoB for CVD risk reduction: a systematic review and meta-analysis of randomised-controlled trials

Oats are a rich source of β-glucan, a viscous, soluble fibre recognised for its cholesterol-lowering properties, and are associated with reduced risk of CVD. Our objective was to conduct a systematic review and meta-analysis of randomised-controlled trials (RCT) investigating the cholesterol-lowering potential of oat β-glucan on LDL-cholesterol, non-HDL-cholesterol and apoB for the risk reduction of CVD. MEDLINE, Embase, CINAHL and Cochrane CENTRAL were searched. We included RCT of ≥3 weeks of follow-up, assessing the effect of diets enriched with oat β-glucan compared with controlled diets on LDL-cholesterol, non-HDL-cholesterol or apoB. Two independent reviewers extracted data and assessed study quality and risk of bias. Data were pooled using the generic inverse-variance method with random effects models and expressed as mean differences with 95 % CI. Heterogeneity was assessed by the Cochran's Q statistic and quantified by the I 2-statistic. In total, fifty-eight trials (n 3974) were included. A median dose of 3·5 g/d of oat β-glucan significantly lowered LDL-cholesterol (-0·19; 95 % CI -0·23, -0·14 mmol/l, P<0·00001), non-HDL-cholesterol (-0·20; 95 % CI -0·26, -0·15 mmol/l, P<0·00001) and apoB (-0·03; 95 % CI -0·05, -0·02 g/l, P<0·0001) compared with control interventions. There was evidence for considerable unexplained heterogeneity in the analysis of LDL-cholesterol (I 2=79 %) and non-HDL-cholesterol (I 2=99 %). Pooled analyses showed that oat β-glucan has a lowering effect on LDL-cholesterol, non-HDL-cholesterol and apoB. Inclusion of oat-containing foods may be a strategy for achieving targets in CVD reduction.

Effect of Oat β-Glucan Intake on Glycaemic Control and Insulin Sensitivity of Diabetic Patients: A Meta-Analysis of Randomized Controlled Trials

Many individual studies on oat β-glucan (OBG) confirmed its functionality in improving type 2 diabetes mellitus (T2DM), but disagreements were identified among those results. To derive a pooled estimate of these results, relevant articles, published before 5 September 2015, were collected from four electronic databases (Pubmed, Cochrane Library, Scopus, and Web of Science) and subjected to meta-analysis in the present work. In total, four articles, dealing with 350 T2DM patients combined, met the inclusion criteria. Compared to control, T2DM patients administrated OBG from 2.5 to 3.5 g/day for 3 to 8 weeks presented significantly lowered concentrations in fasting plasma glucose (FPG) by -0.52 (95% CI: -0.94, -0.10) mmol/L (p = 0.01) and glycosylated hemoglobin (HbA1c) by -0.21% (95% CI: -0.40, -0.02) (p = 0.03). However, OBG intake did not significantly lower the fasting plasma insulin (FPI) concentration. In conclusion, mediate-term OBG intake (3-8 weeks) favored the glycaemic control of T2DM patients but did not improve their insulin sensitivity. Regrettably, data upon the effects of long-term OBG intake on glycaemic control and insulin sensitivity were scarce, which is of much importance and should be addressed in future research.

The Metabolic Effects of Oats Intake in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis

The present study aimed to comprehensively assess if oats intake is beneficial for diabetic patients. The literature search was conducted in PubMed database up to 23 August 2015. Fourteen controlled trials and two uncontrolled observational studies were included. Compared with the controls, oats intake significantly reduced the concentrations of glycosylated hemoglobin A1c (HbA1c) (MD, −0.42%; 95% CI, −0.61% to −0.23%), fasting blood glucose (FBG) (MD, −0.39 mmol/L; 95% CI, −0.58 to −0.19 mmol/L), total cholesterol (TC) (MD, −0.49 mmol/L; 95% CI, −0.86 to −0.12 mmol/L), low-density lipoprotein cholesterol (LDL-C) (MD, −0.29 mmol/L; 95% CI, −0.48 to −0.09 mmol/L). Oatmeal significantly reduced the acute postprandial glucose and insulin responses compared with the control meal. The present study has revealed a beneficial effect of oats intake on glucose control and lipid profiles in type 2 diabetic patients. Further investigations of oats intake in patients with type 1 diabetes and the safety of oats consumption are required.

Effect of oat intake on glycaemic control and insulin sensitivity: a meta-analysis of randomised controlled trials

The present meta-analysis of randomised controlled trials (RCT) aimed to investigate the effect of oat intake on glycaemic control and insulin sensitivity. A literature search was carried out in PubMed, ScienceDirect Online and The Cochrane Library (up to October 2013) for RCT that assessed the effect of oat intake on glucose control and insulin sensitivity. A total of fifteen articles with 673 subjects met the inclusion criteria. A random-effects model was used when the overall pooled studies exhibited significant heterogeneity. Otherwise, a fixed-effects model was used. Compared with controls, oat intake significantly reduced the concentrations of fasting insulin by - 6·29 (95 % CI - 12·32, - 0·27) pmol/l (P= 0·04) and the values of glucose AUC (GAUC; 0-120 min) by - 30·23 (95 % CI - 43·65, - 16·81) min × mmol/l (P< 0·0001). There was a slight decrease in fasting glucose concentrations, glycated Hb concentrations and homeostatic model assessment-insulin resistance values in subjects who consumed oats, but the difference was not significant. In conclusion, oat intake significantly lowers fasting insulin concentrations and GAUC values. To further investigate the effect of oat intake on fasting glucose concentrations, additional long-term and high-quality RCT with a parallel design are required.