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

Underrated aspects of a true Mediterranean diet: understanding traditional features for worldwide application of a "Planeterranean" diet

Over the last decades, the Mediterranean diet gained enormous scientific, social, and commercial attention due to proven positive effects on health and undeniable taste that facilitated a widespread popularity. Researchers have investigated the role of Mediterranean-type dietary patterns on human health all around the world, reporting consistent findings concerning its benefits. However, what does truly define the Mediterranean diet? The myriad of dietary scores synthesizes the nutritional content of a Mediterranean-type diet, but a variety of aspects are generally unexplored when studying the adherence to this dietary pattern. Among dietary factors, the main characteristics of the Mediterranean diet, such as consumption of fruit and vegetables, olive oil, and cereals should be accompanied by other underrated features, such as the following: (i) specific reference to whole-grain consumption; (ii) considering the consumption of legumes, nuts, seeds, herbs and spices often untested when exploring the adherence to the Mediterranean diet; (iii) consumption of eggs and dairy products as common foods consumed in the Mediterranean region (irrespectively of the modern demonization of dietary fat intake). Another main feature of the Mediterranean diet includes (red) wine consumption, but more general patterns of alcohol intake are generally unmeasured, lacking specificity concerning the drinking occasion and intensity (i.e., alcohol drinking during meals). Among other underrated aspects, cooking methods are rather simple and yet extremely varied. Several underrated aspects are related to the quality of food consumed when the Mediterranean diet was first investigated: foods are locally produced, minimally processed, and preserved with more natural methods (i.e., fermentation), strongly connected with the territory with limited and controlled impact on the environment. Dietary habits are also associated with lifestyle behaviors, such as sleeping patterns, and social and cultural values, favoring commensality and frugality. In conclusion, it is rather reductive to consider the Mediterranean diet as just a pattern of food groups to be consumed decontextualized from the social and geographical background of Mediterranean culture. While the methodologies to study the Mediterranean diet have demonstrated to be useful up to date, a more holistic approach should be considered in future studies by considering the aforementioned underrated features and values to be potentially applied globally through the concept of a "Planeterranean" diet.

The Impact of Providing Material Benefits to Improve Access to Food on Clinical Parameters, Dietary Intake, and Household Food Insecurity in People with Diabetes: A Systematic Review with Narrative Synthesis

The high cost of healthy foods makes maintaining a healthy dietary pattern challenging, particularly among people with diabetes who are experiencing food insecurity. The objectives of this study were to: 1) review evidence on the impact of providing material benefits (e.g., food coupons/vouchers, free food, or financial subsidies/incentives) to improve access to food on clinical parameters, dietary intake, and household food insecurity in people with diabetes, and 2) review relevant economic evidence. Six databases were searched from inception to March 2023 for longitudinal studies with quantitative outcomes. Twenty-one studies were included in the primary review and 2 in the economic analysis. Risk of bias was high in 20 studies and moderate in 1 study. The number of randomized controlled trials and nonrandomized studies reporting statistically significant improvement, alongside Grading of Recommendations Assessment, Development, and Evaluation (GRADE) certainty of the evidence was: HbA1c: 1/6 and 4/12 (very low), systolic blood pressure: 0/3 and 1/8 (very low), diastolic blood pressure: 0/3 and 1/7 (very low), BMI: 0/5 and 2/8 (very low), body weight: 0/0 and 1/3 (very low), hypoglycemia: 1/2 and 1/2 (very low), daily intake of fruits and vegetables: 1/1 and 1/3 (very low), daily intake of whole grains: 0/0 and 0/2 (very low), overall diet quality: 2/2 and 1/1 (low), and household food insecurity: 2/3 and 0/0 (very low). The 2 studies included in the economic analysis showed no difference in Medicare spending from Supplemental Nutrition Assistance Program participation and cost-savings from medically tailored meals in an economic simulation. Overall, providing material benefits to improve access to food for people with diabetes may improve household food insecurity, fruit and vegetable intake, and overall diet quality, but effects on clinical parameters and whole grain intake are unclear. The certainty of evidence was very low to low by GRADE. PROSPERO (CRD42021212951).

Adherence to a healthy diet and odds of metabolic syndrome: A cross-sectional study

INTRODUCTION

Metabolic syndrome (MetS) is a major health concern around the world. Dietary factors, including diet quality, play a significant role in its pathophysiology. Healthy Eating Index (HEI) is a tool used as a valid measurement of the individual's diet quality. We aimed at investigating the relationship between diet quality as assessed by HEI-2015 and the risk of MetS and its components in a cross-sectional sample of suburban individuals from PERSIAN Kavar cohort study (PKCS), Fars province, Iran.

METHODS

2225 individuals meeting the eligibility criteria participated in the study. The relevant data were obtained from the baseline phase of PKCS. MetS was defined according to cut-offs presented by the National Cholesterol Education Program Adult Treatment Panel III (ATP III). HEI-2015 was calculated for the included individuals. Odds ratios were estimated. P-values <0.05 were considered as significant.

RESULTS

The overall prevalence of MetS was 27.3%. Individuals with lower HEI-2015 scores had higher odds for MetS and its components. We observed that those who were categorized as the top HEI-2015 tertile had 42% (OR: 0.58; 95% CI: 0.38-0.90) lower odds of high blood pressure in the overall population. Also, the odds of high serum triacylglycerol was lower (OR: 0.72; 95% CI: 0.57-0.90) in those with the highest HEI-2015 scores.

CONCLUSION

We found that higher dietary quality measured by HEI will decrease the risk of developing MetS, hypertension, and hypertriglyceridemia among Iranian adults. However, future interventional studies are required to further elucidate the issue.

The Relationship between Whole-Grain Intake and Measures of Cognitive Decline, Mood, and Anxiety-A Systematic Review

Greater intake of whole grains, compared to refined grains, is consistently associated with a reduced risk of cardiovascular disease and type 2 diabetes, both of which are associated with cognitive decline. To better understand the relationship between whole-grain intake, cognition, mood, and anxiety, a systematic review was conducted to synthesize available evidence linking whole grains to these outcomes. Four electronic databases were searched from inception to August 2021 for potentially relevant observational and interventional studies. Risk of bias (RoB) assessments were performed using the newly developed Nutrition Quality Evaluation Strengthening Tools, and the Grades of Recommendation, Assessment, Development, and Evaluation approach was used to determine the strength of evidence for each outcome. In total, 23 studies [4 randomized controlled trials (RCTs) and 19 observational studies] met the predefined eligibility criteria. Of these,12 studies included analysis of whole-grain intake and cognitive decline, 9 included mood outcomes, and 2 included both cognition and mood outcomes. The overall evidence for an association between whole-grain intake and cognition is inconclusive. With respect to mood outcomes, evidence from RCTs prospective cohort and case-control studies suggest that higher intake is linked to improved outcomes for mood and depression although the evidence is mixed for cross-sectional studies. Reporting of whole-grain intake fell short of suggested standards, and the strength of available evidence was low or very low for all outcomes. A high RoB toward studies reporting results was also noted, complicating both the interpretation of some studies and the combined evidence. Of note, few well-designed RCTs assessing the effect of whole-grain intake on measures of cognition, mood, and anxiety were identified, highlighting the need for more studies in this area. The available, although limited, evidence suggests that greater whole-grain intake is associated with better mood and anxiety-related scores and is inconclusive regarding cognitive outcomes. PROSPERO registration: CRD42021266355.

Health Effects of Whole Grains: A Bibliometric Analysis

Whole grains have been recommended in the diet in most countries, with numerous publications focusing on their health effect. A systematic analysis of these publications on different research methods, regions and perspectives will contribute to an understanding of the innovation pattern in this field. This bibliometric study analyzes the global publication characteristics, hotspots and frontiers of whole grain health benefit research, and discusses the trends and prospects of this topic. The overall number of publications is on the rise, with the United States contributing the most publications. The most cited literature shows that observational studies, systematic reviews and meta-analysis are the most widely used methods. The main focus in this area is on dietary fiber and bioactive substances, while the latter has received increased attention in recent years in particular. With the increasingly prominent problems of hidden hunger and chronic disease, the development of whole grain foods and their optimum intake have gradually become hot topics. In addition to the need to reveal the mechanism of whole grain health effects, consensus needs to be reached on standards and definitions for whole grain foods, and attention should be paid to the retention of taste and healthy nutrients in processing.

Associations between dietary fiber intake and cardiovascular risk factors: An umbrella review of meta-analyses of randomized controlled trials

Although several meta-analyses have revealed the beneficial effects of dietary fiber intake on human health, some have reported inconsistent findings. The purpose of this work was to perform an umbrella meta-analysis to evaluate the relevant evidence and elucidate the effect of dietary fiber intake on glycemic control, lipid profiles, systematic inflammation, and blood pressure. Eligible studies were searched in several electronic databases, including Web of Science, PubMed, Scopus, and the Cochrane Library, up to March 2022. A total of 52 meta-analyses involving 47,197 subjects were identified to assess the pooled effect size. Overall, higher dietary fiber intake was significantly associated with reductions in parameters involving glycemic control, including fasting plasma glucose (ES = -0.55, 95% CI: -0.73, -0.38, P < 0.001), fasting plasma insulin (ES = -1.22, 95% CI: -1.63, -0.82, P < 0.001), homeostasis model assessment of insulin resistance (HOMA-IR) (ES = -0.43, 95% CI: -0.60, -0.27, P < 0.001), and glycosylated hemoglobin (HbA1c) (ES = -0.38, 95% CI: -0.50, -0.26, P < 0.001). In terms of lipid profiles, higher dietary fiber intake was associated with significant reductions in the serum level of total cholesterol (ES = -0.28, 95% CI: -0.39, -0.16, P < 0.001) and low-density lipoprotein cholesterol (ES = -0.25, 95% CI: -0.34, -0.16, P < 0.001), but not triglycerides (ES = -0.001, 95% CI: -0.006, 0.004, P = 0.759) and high-density lipoprotein cholesterol (ES = -0.002, 95% CI: -0.004, 0.000, P = 0.087). Higher dietary fiber intake was also significantly associated with improved tumor necrosis factor-alpha serum levels (ES = -0.78, 95% CI: -1.39, -0.16, P = 0.013), while no significant effect was observed for C-reactive protein (ES = -0.14, 95% CI: -0.33, 0.05, P = 0.156). Finally, blood pressure was also significantly improved following higher dietary fiber intake (systolic blood pressure: ES = -1.72, 95% CI: -2.13, -1.30, P < 0.001; diastolic blood pressure: ES = -0.67, 95% CI: -0.96, -0.37, P < 0.001). Subgroup analysis revealed that the study population and type of dietary fiber could be partial sources of heterogeneity. In conclusion, the present umbrella meta-analysis provides evidence for the role of dietary fiber supplementation in the improvement of established cardiovascular risk factors.

Effects of Diet, Lifestyle, Chrononutrition and Alternative Dietary Interventions on Postprandial Glycemia and Insulin Resistance

As years progress, we are found more often in a postprandial than a postabsorptive state. Chrononutrition is an integral part of metabolism, pancreatic function, and hormone secretion. Eating most calories and carbohydrates at lunch time and early afternoon, avoiding late evening dinner, and keeping consistent number of daily meals and relative times of eating occasions seem to play a pivotal role for postprandial glycemia and insulin sensitivity. Sequence of meals and nutrients also play a significant role, as foods of low density such as vegetables, salads, or soups consumed first, followed by protein and then by starchy foods lead to ameliorated glycemic and insulin responses. There are several dietary schemes available, such as intermittent fasting regimes, which may improve glycemic and insulin responses. Weight loss is important for the treatment of insulin resistance, and it can be achieved by many approaches, such as low-fat, low-carbohydrate, Mediterranean-style diets, etc. Lifestyle interventions with small weight loss (7–10%), 150 min of weekly moderate intensity exercise and behavioral therapy approach can be highly effective in preventing and treating type 2 diabetes. Similarly, decreasing carbohydrates in meals also improves significantly glycemic and insulin responses, but the extent of this reduction should be individualized, patient-centered, and monitored. Alternative foods or ingredients, such as vinegar, yogurt, whey protein, peanuts and tree nuts should also be considered in ameliorating postprandial hyperglycemia and insulin resistance. This review aims to describe the available evidence about the effects of diet, chrononutrition, alternative dietary interventions and exercise on postprandial glycemia and insulin resistance.