Cereal fiber, fruit fiber, and type 2 diabetes: Explaining the paradox

Effect of Dietary Approaches to Stop Hypertension (DASH) on Patients with Metabolic Syndrome and Its Potential Mechanisms

Metabolic syndrome (MS) is more prevalent in chronic diseases and, if left untreated, can lead to serious consequences, such as cardiovascular disease (CVD), cerebrovascular disease and type 2 diabetes, which have become significant public health issues globally. Metabolic syndrome is significantly influenced by the daily diet of patients. The dietary approaches to stop hypertension (DASH) diet, originally designed to prevent or control hypertension, offers additional metabolic benefits due to its nutrient composition. The DASH diet recommends the intake of potassium, magnesium, calcium and fibre while limiting total fat, saturated fat and sodium, which is beneficial for patients with MS. Due to its limited fat content and high levels of fibre and calcium, individuals following the DASH diet are less prone to being overweight and obese and have lower concentrations of total and low-density lipoprotein cholesterol. Moreover, the DASH diet can reduce blood pressure and is effective in correcting glucose and insulin abnormalities. This review comprehensively summarises the health benefits of the DASH diet on the risk factors of MS and describes the potential mechanisms based on available evidence.

Current Research on the Role of Isomaltooligosaccharides in Gastrointestinal Health and Metabolic Diseases

The intestinal epithelium plays an important role in maintaining the intestinal barrier and facilitating nutrient absorption. It also serves as a critical physical barrier against the infiltration of foreign substances from the intestinal lumen into the circulation. Intestinal barrier dysfunction has been implicated in the development of several diseases. Isomaltooligosaccharides (IMOs), which are a type of dietary fiber, possess multiple health benefits. However, there is limited information regarding their efficacy against gastrointestinal diseases. This review explores the therapeutic potential of IMOs in obesity, diabetes mellitus, inflammatory bowel disease (IBD), hyperlipidemia, and constipation. High-fat diet (HFD)-induced obesity models have shown that IMOs, administered alone or in combination with other compounds, exhibit potent antiobesity effects, making them promising agents in the treatment of obesity and its associated complications. Moreover, IMOs exhibit preventive effects against HFD-induced metabolic dysfunction by modulating gut microbiota and short-chain fatty acid levels, thereby ameliorating symptoms. Furthermore, IMOs can reduce IBD and alleviate hyperlipidemia, as indicated by the reduced histological colitis scores and improved lipid profiles observed in clinical trials and animal studies. This review highlights IMOs as a versatile intervention strategy that can improve gastrointestinal health by modulating gut microbiota, immune responses, and metabolic parameters, providing a multifaceted approach to address the complex nature of gastrointestinal disorders.

Improved Gut Health May Be a Potential Therapeutic Approach for Managing Prediabetes: A Literature Review

Given the growing global threat and rising prevalence of type 2 diabetes mellitus (T2DM), addressing this metabolic disease is imperative. T2DM is preceded by prediabetes (PD), an intermediate hyperglycaemia that goes unnoticed for years in patients. Several studies have shown that gut microbial diversity and glucose homeostasis in PD or T2DM patients are affected. Therefore, this review aims to synthesize the existing literature to elucidate the association between high-calorie diets, intestinal permeability and their correlation with PD or T2DM. Moreover, it discusses the beneficial effects of different dietary interventions on improving gut health and glucose metabolism. The primary factor contributing to complications seen in PD or T2DM patients is the chronic consumption of high-calorie diets, which alters the gut microbial composition and increases the translocation of toxic substances from the intestinal lumen into the bloodstream. This causes an increase in inflammatory response that further impairs glucose regulation. Several dietary approaches or interventions have been implemented. However, only a few are currently in use and have shown promising results in improving beneficial microbiomes and glucose metabolism. Therefore, additional well-designed studies are still necessary to thoroughly investigate whether improving gut health using other types of dietary interventions can potentially manage or reverse PD, thereby preventing the onset of T2DM.

Dietary fiber intake and its association with diabetic kidney disease in American adults with diabetes: A cross-sectional study

BACKGROUND

Dietary fiber (DF) intake may have a protective effect against type 2 diabetes (T2D); however, its relationship with diabetic kidney disease (DKD) remains unclear.

AIM

To investigate the potential association between DF intake and the prevalence of DKD in individuals diagnosed with T2D.

METHODS

This cross-sectional study used data from the National Health and Nutrition Examination Survey collected between 2005 and 2018. DF intake was assessed through 24-h dietary recall interviews, and DKD diagnosis in individuals with T2D was based on predefined criteria, including albuminuria, impaired glomerular filtration rate, or a combination of both. Logistic regression analysis was used to assess the association between DF intake and DKD, and comprehensive subgroup and sensitivity analyses were performed.

RESULTS

Among the 6032 participants, 38.4% had DKD. With lower DF intake-T1 (≤ 6.4 g/1000 kcal/day)-as a reference, the adjusted odds ratio for DF and DKD for levels T2 (6.5-10.0 g/1000 kcal/day) and T3 (≥ 10.1 g/1000 kcal/day) were 0.97 (95%CI: 0.84-1.12, P = 0.674) and 0.79 (95%CI: 0.68-0.92, P = 0.002), respectively. The subgroup analysis yielded consistent results across various demographic and health-related subgroups, with no statistically significant interactions (all P > 0.05).

CONCLUSION

In United States adults with T2D, increased DF intake may be related to reduced DKD incidence. Further research is required to confirm these findings.

Polysaccharides (pectin, mucilage, and fructan inulin) and their fermented products: A critical analysis of their biochemical, gut interactions, and biological functions as antidiabetic agents

Diabetes mellitus is a globally metabolic endocrine syndrome marked by a deficiency of insulin secretion (type-1 DM) or glucose intolerance arising from insulin response impairment (type-2 DM) leading to abnormal glucose metabolism. With an increasing interest in natural dietary components for diabetes management, the identification of novel agents witnessed major discoveries. Plant-derived mucilage, pectin, and inulin are important non-starch polysaccharides that exhibit effective antidiabetic properties often termed soluble dietary fiber (SDF). SDF affects sugar metabolism through multiple mechanisms affecting glucose absorption and diffusion, modulation of carbohydrate metabolizing enzymes (α-amylase and α-glucosidase), ameliorating β-pancreatic cell dysfunction, and improving insulin release or sensitivity. Certain SDFs inhibit dipeptidyl peptidase-4 and influence the expression levels of genes related to glucose metabolism. This review is designed to discuss holistically and critically the antidiabetic effects of major SDF and their underlying mechanisms of action. This review should aid drug discovery approaches in developing novel natural antidiabetic drugs from SDF.

Nutrition at the Intersection between Gut Microbiota Eubiosis and Effective Management of Type 2 Diabetes

Nutrition is one of the most influential environmental factors in both taxonomical shifts in gut microbiota as well as in the development of type 2 diabetes mellitus (T2DM). Emerging evidence has shown that the effects of nutrition on both these parameters is not mutually exclusive and that changes in gut microbiota and related metabolites such as short-chain fatty acids (SCFAs) and branched-chain amino acids (BCAAs) may influence systemic inflammation and signaling pathways that contribute to pathophysiological processes associated with T2DM. With this background, our review highlights the effects of macronutrients, carbohydrates, proteins, and lipids, as well as micronutrients, vitamins, and minerals, on T2DM, specifically through their alterations in gut microbiota and the metabolites they produce. Additionally, we describe the influences of common food groups, which incorporate varying combinations of these macronutrients and micronutrients, on both microbiota and metabolic parameters in the context of diabetes mellitus. Overall, nutrition is one of the first line modifiable therapies in the management of T2DM and a better understanding of the mechanisms by which gut microbiota influence its pathophysiology provides opportunities for optimizing dietary interventions.

Potential roles of cereal bioactive compounds in the prevention and treatment of type 2 diabetes: A review of the current knowledge

Diabetes is one of the most common non-communicable diseases in both developed and underdeveloped countries with a 9.3% prevalence. Unhealthy diets and sedentary lifestyles are among the most common reasons for type 2 diabetes mellitus (T2DM). Diet plays a crucial role in both the etiology and treatment of T2DM. There are several recommendations regarding the carbohydrate intake of patients with T2DM. One of them is about reducing the total carbohydrate intake and/or changing the type of carbohydrate to reduce the glycaemic index. Cereals are good sources of carbohydrates in the diet with a significant amount of soluble and non-soluble fiber content. Apart from fiber, it has been shown that the bioactive compounds present in cereals such as proteins, phenolic compounds, carotenoids, and tocols have beneficial impacts in the prevention and treatment of T2DM. Moreover, cereal by-products especially the by-products of milling processes, which are bran and germ, have been reported to have anti-diabetic activities mainly because of their fiber and polyphenols content. Considering the potential functions of cereals in patients with T2DM, this review focuses on the roles of cereal bioactive compounds in the prevention and treatment of type 2 diabetes.

Dietary fiber - a scoping review for Nordic Nutrition Recommendations 2023

Dietary fiber is a term crudely defined as carbohydrates (CHOs) that escape digestion and uptake in the small intestine. Lignin, which is not a CHO, is also a part of the dietary fiber definition. Dietary fibers come in different sizes and forms, with a variety of combinations of monomeric units. Health authorities worldwide have for many years recommended a diet rich in dietary fibers based on consistent findings that dietary fibers are associated with reduced incidences of major non-communicable diseases, including obesity, type 2 diabetes, cardiovascular disease, and colorectal cancer. Most fibers come from common edible foods from the plant kingdom, but fibers are also found in food additives, supplements, and breast milk. The recommended intake in Nordic Nutrition Recommendations 2012 (NNR2012) is 25 g/d for women and 35 g/d for men, whereas the actual intake is significantly lower, ranging from 16 g/d to 22 g/d in women and 18 g/d to 26 g/d in men. New studies since NNR2012 confirm the current view that dietary fiber is beneficial for health, advocating intakes of at least 25 g/day.

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.

High cereal fibre but not total fibre is associated with a lower risk of type 2 diabetes: Evidence from the Melbourne Collaborative Cohort Study

AIM

To assess the associations of total dietary fibre and fibre from different food sources (ie, cereal, fruit and vegetables) with the risk of diabetes.

MATERIALS AND METHODS

The Melbourne Collaborative Cohort Study enrolled 41 513 participants aged 40 to 69 years from 1990 to 1994. The first and second follow-ups were conducted in 1994 to 1998 and 2003 to 2007, respectively. Self-reported diabetes incidence was recorded at both follow-ups. We analysed data from 39 185 participants, with a mean follow-up of 13.8 years. The relationships between dietary fibre intake (total, fruit, vegetable and cereal fibre) and the incidence of diabetes were assessed using modified Poisson regression, adjusted for dietary, lifestyle, obesity, socioeconomic and other possible confounders. Fibre intake was categorized into quintiles.

RESULTS

At total of 1989 incident cases were identified over both follow-up surveys. Total fibre intake was not associated with diabetes risk. Higher intake of cereal fibre (P for trend = 0.003), but not fruit (P for trend = 0.3) and vegetable fibre (P for trend = 0.5), was protective against diabetes. For cereal fibre, quintile 5 versus quintile 1 showed a 25% reduction in diabetes risk (incidence risk ratio [IRR] 0.75, 95% confidence interval [CI] 0.63-0.88). For fruit fibre, only quintile 2 versus quintile 1 showed a 16% risk reduction (IRR 0.84, 95% CI 0.73-0.96). Adjustment for body mass index (BMI) and waist-to-hip ratio eliminated the association and mediation analysis showed that BMI mediated 36% of the relationship between fibre and diabetes.

CONCLUSION

Intake of cereal fibre and, to a lesser extent, fruit fibre, may reduce the risk of diabetes, while total fibre showed no association. Our data suggest that specific recommendations regarding dietary fibre intake may be needed to prevent diabetes.

Advances in extraction, purification, structural characteristics and biological activities of hemicelluloses: A review

Hemicelluloses, a major component of plant cell walls, are a non-cellulosic heteropolysaccharide composed of several distinct sugars that is second in abundance to cellulose, which are one of the most abundant and cheapest renewable resources on earth. Hemicelluloses structure is complex and its chemical structure varies greatly among the different plant species. In addition to its wide use in production of feed and other chemical materials, hemicelluloses are known for its remarkable biological activities that remain largely underutilised to date. Therefore, comprehensive investigations of hemicelluloses structural and biological properties would be helpful for achieving rational utilisation and high-value conversion of this underutilised substance into agents with enhanced health benefits for incorporation in drugs and health foods. In this review, details of diverse research initiatives that have enhanced our understanding of hemicelluloses properties are summarised, including hemicelluloses sources, extraction and purification methods, structural characteristics and biological activities. Furthermore, hemicelluloses structure-activity relationships and new directions for future hemicelluloses research studies are discussed.

Functional constituents of plant-based foods boost immunity against acute and chronic disorders

Plant-based foods are becoming an increasingly frequent topic of discussion, both scientific and social, due to the dissemination of information and exchange of experiences in the media. Plant-based diets are considered beneficial for human health due to the supply of many valuable nutrients, including health-promoting compounds. Replacing meat-based foods with plant-based products will provide many valuable compounds, including antioxidants, phenolic compounds, fibers, vitamins, minerals, and some ω3 fatty acids. Due to their high nutritional and functional composition, plant-based foods are beneficial in acute and chronic diseases. This article attempts to review the literature to present the most important data on nutrients of plant-based foods that can then help in the prevention of many diseases, such as different infections, such as coronavirus disease, pneumonia, common cold and flu, asthma, and bacterial diseases, such as bronchitis. A properly structured plant-based diet not only provides the necessary nutrients but also can help in the prevention of many diseases.

Structural and Potential Functional Properties of Alkali-Extracted Dietary Fiber From Antrodia camphorata

Antrodia camphorata is rich in a variety of bioactive ingredients; however, the utilization efficiency of the residue of A. camphorata is low, resulting in serious waste. It is necessary to deeply study the functional components of A. camphorata residues to achieve high-value utilization. In this study, the components, structural characteristics, and functional properties of alkali-extracted dietary fiber extracted from residues of A. camphorata (basswood and dish cultured fruiting body, respectively) were investigated. There were similar components and structural characteristics of ACA-DK (extract from basswood cultured) and ACA-DF (extract from dish cultured). The two alkali-extracted dietary fiber were composed of mainly cellulose and xylan. However, ACA-DK has better adsorption capacities than ACA-DF on lipophilic substances such as oil (12.09 g/g), cholesterol (20.99 mg/g), and bile salts (69.68 mg/g). In vitro immunomodulatory assays stated that ACA-DK had a good effect on promoting the proliferation of RAW 264.7 cells and can activate cell phagocytosis, NO synthesis, and other immune capabilities. The edible fungus A. camphorata is a good source of functional dietary fiber. The alkali-extracted dietary fiber of A. camphorata might be used as a functional ingredient in the medicine and food industry.

A Three-Day Intervention With Granola Containing Cereal Beta-Glucan Improves Glycemic Response and Changes the Gut Microbiota in Healthy Individuals: A Crossover Study

Intake of soluble fibers including beta-glucan, is known to improve post-prandial glycemic response. The mechanisms have been attributed to the viscous gel forming in the stomach and small intestine, giving a longer absorption time. However, recent evidence suggests a link between intake of beta-glucan and improved glycemic regulation at subsequent meals through the gut microbiota. We investigated the short-term effect of granola with different amounts of cereal beta-glucan on glycemic response and gut microbiota. After a two-week run-in period (baseline), fourteen healthy, normal weight adults completed a dose-response dietary crossover study. Different amounts of cereal beta-glucan (low: 0.8 g, medium: 3.2 g and high: 6.6 g) were provided in granola and eaten with 200 ml low-fat milk as an evening meal for three consecutive days. Blood glucose and insulin were measured fasted and after an oral glucose tolerance test (OGTT) the following day, in addition to peptide YY (PYY) and glucagon-like peptide (GLP-2), fasting short chain fatty acids (SCFA) in blood, breath H2, and gut microbiota in feces. Only the intervention with medium amounts of beta-glucan decreased blood glucose and insulin during OGTT compared to baseline. Fasting PYY increased with both medium and high beta-glucan meal compared to the low beta-glucan meal. The microbiota and SCFAs changed after all three interventions compared to baseline, where acetate and butyrate increased, while propionate was unchanged. Highest positive effect size after intake of beta-glucan was found with Haemophilus, followed by Veillonella and Sutterella. Furthermore, we found several correlations between different bacterial taxa and markers of glycemic response. In summary, intake of granola containing 3.2 g cereal beta-glucan as an evening meal for three consecutive days reduced the glycemic response after an OGTT 0-180 min and changed gut microbiota composition. Since we cannot rule out that other fiber types have contributed to the effect, more studies are needed to further explore the effect of cereal beta-glucan on glycemic regulation.

Clinical Trial Registration

[www.clinicaltrials.gov], identifier [NCT03293693].

New alternatives from sustainable sources to wheat in bakery foods: Science, technology, and challenges

Ongoing research in the food industry is striving to replace wheat flour with new alternatives from sustainable sources to overcome the disease burden in the existing population. Celiac disease, wheat allergy, gluten sensitivity, or non-celiac gluten sensitivity are some common disorders associated with gluten present in wheat. These scientific findings are crucial to finding appropriate alternatives in introducing new ingredients supporting the consumer's requirements. Among the alternatives, amaranth, barley, coconut, chestnut, maize, millet, teff, oat, rye, sorghum, soy, rice flour, and legumes could be considered appropriate due to their chemical composition, bioactive profile, and alternatives utilization in the baking industry. Furthermore, the enrichment of these alternatives with proper ingredients is considered effective. Literature demonstrated that the flours from these alternative sources significantly enhanced the physicochemical, pasting, and rheological properties of the doughs. These flours boost a significant reduction in gluten proteins associated with food intolerance, in comparison with wheat highlighting a visible market opportunity with nutritional and organoleptic benefits for food producers. PRACTICAL APPLICATIONS: New alternatives from sustainable sources to wheat in bakery foods as an approach that affects human health. Alternatives from sustainable sources are important source of nutrients and bioactive compounds. Alternatives from sustainable sources are rising due to nutritional and consumer demand in bakery industry. New alternatives from sustainable sources improve physicochemical, pasting, and rheological properties of dough. Non-wheat-based foods from non-traditional grains have a potential to increase consumer market acceptance.

Current Research on the Effects of Non-Digestible Carbohydrates on Metabolic Disease

Metabolic diseases (MDs), including cardiovascular diseases (CVDs) and diabetes, occur when the body’s normal metabolic processes are disrupted. Behavioral risk factors such as obesity, physical inactivity, and dietary habits are strongly associated with a higher risk of MD. However, scientific evidence strongly suggests that balanced, healthy diets containing non-digestible carbohydrates (NDCs), such as dietary fiber and resistant starch, can reduce the risk of developing MD. In particular, major properties of NDCs, such as water retention, fecal bulking, viscosity, and fermentation in the gut, have been found to be important for reducing the risk of MD by decreasing blood glucose and lipid levels, increasing satiety and insulin sensitivity, and modifying the gut microbiome. Short chain fatty acids produced during the fermentation of NDCs in the gut are mainly responsible for improvement in MD. However, the effects of NDCs are dependent on the type, source, dose, and duration of NDC intake, and some of the mechanisms underlying the efficacy of NDCs on MD remain unclear. In this review, we briefly summarize current studies on the effects of NDCs on MD and discuss potential mechanisms that might contribute to further understanding these effects.

Exploring diet associations with Covid-19 and other diseases: a Network Analysis-based approach

The current global pandemic, Covid-19, is a severe threat to human health and existence especially when it is mutating very frequently. Being a novel disease, Covid-19 is impacting the patients with comorbidities and is predicted to have long-term consequences, even for those who have recovered from it. To clearly recognize its impact, it is important to comprehend the complex relationship between Covid-19 and other diseases. It is also being observed that people with good immune system are less susceptible to the disease. It is perceived that if a correlation between Covid-19, other diseases, and diet is realized, then caregivers would be able to enhance their further course of medical action and recommendations. Network Analysis is one such technique that can bring forth such complex interdependencies and associations. In this paper, a Network Analysis-based approach has been proposed for analyzing the interplay of diets/foods along with Covid-19 and other diseases. Relationships between Covid-19, diabetes mellitus type 2 (T2DM), non-alcoholic fatty liver disease (NAFLD), and diets have been curated, visualized, and further analyzed in this study so as to predict unknown associations. Network algorithms including Louvain graph algorithm (LA), K nearest neighbors (KNN), and Page rank algorithms (PR) have been employed for predicting a total of 60 disease-diet associations, out of which 46 have been found to be either significant in disease risk prevention/mitigation or in its progression as validated using PubMed literature. A precision of 76.7% has been achieved which is significant considering the involvement of a novel disease like Covid-19. The generated interdependencies can be further explored by medical professionals and caregivers in order to plan healthy eating patterns for Covid-19 patients. The proposed approach can also be utilized for finding beneficial diets for different combinations of comorbidities with Covid-19 as per the underlying health conditions of a patient. Graphical abstract.

Habitual Dietary Fiber Intake, Fecal Microbiota, and Hemoglobin A1c Level in Chinese Patients with Type 2 Diabetes

High-fiber diet interventions have been proven to be beneficial for gut microbiota and glycemic control in diabetes patients. However, the effect of a low level of fiber in habitual diets remains unclear. This study aims to examine the associations of habitual dietary fiber intake with gut microbiome profiles among Chinese diabetes patients and identify differential taxa that mediated associations of dietary fiber with HbA1c level. Two cross-sectional studies and one longitudinal study were designed based on two follow-up surveys in a randomized trial conducted during 2015−2017. The study included 356 and 310 participants in the first and second follow-ups, respectively, with 293 participants in common in both surveys. Dietary fiber intake was calculated based on a 3-day 24-h diet recall at each survey and was classified into a lower or a higher group according to the levels taken based on the two surveys using 7.2 g/day as a cut-off value. HbA1c was assayed to assess glycemic status using a cut-off point of 7.0% and 8.0%. Microbiome was profiled by 16S rRNA sequencing. A high habitual dietary fiber intake was associated with a decrease in α-diversity in both the cross-sectional and longitudinal analyses. At the first follow−up, phylum Firmicutes and Fusobacteria were negatively associated with a higher dietary fiber intake (p < 0.05, Q < 0.15); at the second follow-up, genus Adlercreutzia, Prevotella, Ruminococcus, and Desulfovibrio were less abundant in patients taking higher dietary fiber (p < 0.05, Q < 0.15); genus Desulfovibrio and Ruminococcaceae (Unknown), two identified differential taxa by HbA1c level, were negatively associated with dietary fiber intake in both the cross-sectional and longitudinal analyses, and mediated the dietary fiber-HbA1c associations among patients taking dietary fiber ≥ 7.2 g/day (mediation effect β [95%CI]: −0.019 [−0.043, −0.003], p = 0.018 and −0.019 [−0.046, −0.003], p = 0.016). Our results suggest that habitual dietary fiber intake has a beneficial effect on gut microbiota in Chinese diabetes patients. Further studies are needed to confirm our results.

The regulatory roles of dietary fibers on host health via gut microbiota-derived short chain fatty acids

As a component of nutraceuticals, dietary fibers (DFs) are essential for maintain human growth and health via the regulation of gut microbiota in the digestive tract. In this review, we summarize food-derived DFs and their effect on gut microbiota-derived short-chain fatty acids (SCFAs). DFs accelerate the production of SCFAs mainly by stimulating intestinal Lactobacillus, Bifidobacterium and Akkermansia to treat diabetes, obesity, cancer, inflammation and immunodeficiency. Further studies should focus on clarifying the detailed mechanism between DFs and diseases associated with gut microbiota-mediated SCFAs.

Nutrients and Dietary Approaches in Patients with Type 2 Diabetes Mellitus and Cardiovascular Disease: A Narrative Review

Cardiovascular disease (CVD) is the most common cause of morbidity and mortality in developed countries. The prevalence of CVD is much higher in patients with type 2 diabetes mellitus (T2DM), who may benefit from lifestyle changes, which include adapted diets. In this review, we provide the role of different groups of nutrients in patients with T2DM and CVD, as well as dietary approaches that have been associated with better and worse outcomes in those patients. Many different diets and supplements have proved to be beneficial in T2DM and CVD, but further studies, guidelines, and dietary recommendations are particularly required for patients with both diseases.

Soluble Dietary Fiber, One of the Most Important Nutrients for the Gut Microbiota

Dietary fiber is a widely recognized nutrient for human health. Previous studies proved that dietary fiber has significant implications for gastrointestinal health by regulating the gut microbiota. Moreover, mechanistic research showed that the physiological functions of different dietary fibers depend to a great extent on their physicochemical characteristics, one of which is solubility. Compared with insoluble dietary fiber, soluble dietary fiber can be easily accessed and metabolized by fiber-degrading microorganisms in the intestine and produce a series of beneficial and functional metabolites. In this review, we outlined the structures, characteristics, and physiological functions of soluble dietary fibers as important nutrients. We particularly focused on the effects of soluble dietary fiber on human health via regulating the gut microbiota and reviewed their effects on dietary and clinical interventions.

The Effects of Almonds on Gut Microbiota, Glycometabolism, and Inflammatory Markers in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

The use of nutritional interventions for managing diabetes is one of the effective strategies aimed at reducing the global prevalence of the condition, which is on the rise. Almonds are the most consumed tree nut and they are known to be rich sources of protein, monounsaturated fatty acids, essential minerals, and dietary fibre. Therefore, the aim of this review was to evaluate the effects of almonds on gut microbiota, glycometabolism, and inflammatory parameters in patients with type 2 diabetes.

METHODS

This systematic review and meta-analysis was carried out according to the preferred reporting items for systematic review and meta-analysis (PRISMA). EBSCOhost, which encompasses the Health Sciences Research Databases; Google Scholar; EMBASE; and the reference lists of articles were searched based on population, intervention, control, outcome, and study (PICOS) framework. Searches were carried out from database inception until 1 August 2021 based on medical subject headings (MesH) and synonyms. The meta-analysis was carried out with the Review Manager (RevMan) 5.3 software.

RESULTS

Nine randomised studies were included in the systematic review and eight were used for the meta-analysis. The results would suggest that almond-based diets have significant effects in promoting the growth of short-chain fatty acid (SCFA)-producing gut microbiota. Furthermore, the meta-analysis showed that almond-based diets were effective in significantly lowering (p < 0.05) glycated haemoglobin (HbA1c) levels and body mass index (BMI) in patients with type 2 diabetes. However, it was also found that the effects of almonds were not significant (p > 0.05) in relation to fasting blood glucose, 2 h postprandial blood glucose, inflammatory markers (C-reactive protein and Tumour necrosis factor α, TNF-α), glucagon-like peptide-1 (GLP-1), homeostatic model assessment of insulin resistance (HOMA-IR), and fasting insulin. The biological mechanisms responsible for the outcomes observed in this review in relation to reduction in HbA1c and BMI may be based on the nutrient composition of almonds and the biological effects, including the high fibre content and the low glycaemic index profile.

CONCLUSION

The findings of this systematic review and meta-analysis have shown that almond-based diets may be effective in promoting short-chain fatty acid-producing bacteria and lowering glycated haemoglobin and body mass index in patients with type 2 diabetes compared with control. However, the effects of almonds were not significant (p > 0.05) with respect to fasting blood glucose, 2 h postprandial blood glucose, inflammatory markers (C-reactive protein and TNF-α), GLP-1, HOMA-IR, and fasting insulin.

An Update on the Epidemiology of Type 2 Diabetes: A Global Perspective

Type 2 diabetes (T2D) is a public health burden associated with immense health care and societal costs, early death, and morbidity. Largely because of epidemiologic changes, including nutrition transitions, urbanization, and sedentary lifestyles, T2D is increasing in every region of the world, particularly in low-income and middle-income countries. This article highlights global trends in T2D and discusses the role of genes, early-life exposures, and lifestyle risk factors in the cause of T2D, with an emphasis on populations in current hotspots of the epidemic. It also considers potential impacts of the coronavirus disease 2019 pandemic and T2D prevention policies and action.

Specific fruit but not total fruit intake during early pregnancy is inversely associated with gestational diabetes mellitus risk: a prospective cohort study

OBJECTIVES

Fruit intake may influence gestational diabetes mellitus (GDM) risk. However, prospective evidence remains controversial and limited. The current study aimed to investigate whether total fruit and specific fruit intake influence GDM risk.

DESIGN

A prospective cohort study was conducted. Dietary information was collected by a 3-d 24-h dietary recall. All participants underwent a standard 75-g oral glucose tolerance test at 24-28 gestational weeks. Log-binomial models were used to estimate the association between fruit intake and GDM risk, and the results are presented as relative risks (RR) and 95 % CI.

SETTING

Southwest China.

PARTICIPANTS

Totally, 1453 healthy pregnant women in 2017.

RESULTS

Total fruit intake was not associated with lower GDM risk (RR of 1·03 (95 % CI 0·83, 1·27) (Ptrend = 0·789)). The RR of GDM risk was 0·73 for the highest anthocyanin-rich fruit intake quartile compared with the lowest quartile (95 % CI 0·56, 0·93; Ptrend = 0·015). A higher grape intake had a linear inverse association with GDM risk (Q4 v. Q1: RR = 0·65; 95 % CI 0·43, 0·98; Ptrend = 0·044), and after further adjustment for anthocyanin intake, the inverse association tended to be non-linear (Q4 v. Q1: RR = 0·65; 95 % CI 0·44, 0·98; Ptrend = 0·079). However, we did not find an association between glycaemic index-grouped fruit, glycaemic load-grouped fruit or other fruit subtype intake and GDM risk.

CONCLUSIONS

In conclusion, specific fruit intake (particularly anthocyanin-rich fruit and grapes) but not total fruit intake was inversely associated with GDM risk.

Procyanidin B1 and p-Coumaric Acid from Highland Barley Grain Showed Synergistic Effect on Modulating Glucose Metabolism via IRS-1/PI3K/Akt Pathway

INTRODUCTION

Phenolic extract in highland barley grain has showed hypoglycemic effect, while little information is available about the active compounds and whether there exist additive or synergistic effect on modulating glucose metabolism.

METHODS AND RESULTS

Procyanidin B1 (PB) and p-coumaric acid (CA) are the active compounds in highland barley grain and show synergistic effect on improving glucose uptake and glycogen synthesis by upregulating glucose transporter (GLUT4) and downregulating glycogen synthase kinase-3β (GSK-3β) protein expression, respectively. The mechanism may be attributed to target insulin receptor (IRβ) and regulate insulin receptor substrate-1 (IRS-1)/phosphatidylinositol 3-kinase (PI3K)/ protein kinase B (Akt) pathway. Furthermore, PB + CA exhibits synergistic effect on restoring glucose intolerance and insulin resistance, and improving hepatic glycogen synthesis in impaired glucose tolerance (IGT) mice. The postprandial blood glucose (PBG), homeostasis model assessment (HOMA)-IR values and serum insulin contents in PB + CA-treated IGT mice with dosage of 300 mg kg^-1 BW are reversed to normal levels. Additionally, PC + CA shows additive effect on inhibiting gluconeogenesis in vitro and in vivo.

CONCLUSION

PB + CA in highland barley grain synergistically modulate glucose metabolism. These results may provide evidence of whole highland barley grain diet achieve superior effect on restoring IGT than isolated components.

Association of Habitual Preoperative Dietary Fiber Intake With Complications After Colorectal Cancer Surgery

IMPORTANCE

Postoperative complications are associated with increased morbidity and mortality among patients with colorectal cancer. As a modifiable factor associated with gut health, dietary fiber intake is of interest with regard to the risk of complications after surgery for colorectal cancer.

OBJECTIVE

To examine the association between preoperative dietary fiber intake and risk of complications after surgery for colorectal cancer.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used data from the Colorectal Longitudinal, Observational Study on Nutritional and Lifestyle Factors (COLON) study, which recruited adult patients with colorectal cancer at any stage at diagnosis from 11 hospitals in the Netherlands between August 2010 and December 2017. The present study included patients with stage I to IV colorectal cancer who underwent elective abdominal surgery. Data were analyzed between December 2019 and September 2020.

EXPOSURES

Habitual dietary fiber intake was assessed at diagnosis using a 204-item food frequency questionnaire.

MAIN OUTCOMES AND MEASURES

Any complications, surgical complications, and anastomotic leakage occurring during the 30 days after surgery for colorectal cancer. The association between fiber intake and risk of postoperative complications was assessed using logistic regression analyses. Additional analyses stratified by sex, tumor location, and fiber source were performed.

RESULTS

Among the 1399 patients included in the analysis, the median age at inclusion was 66 years (interquartile range, 61-72 years) and 896 (64%) were men. Any complications occurred in 397 patients (28%), and surgical complications occurred in 235 patients (17%). Of 1237 patients with an anastomosis, 67 (5%) experienced anastomotic leakage. Higher dietary fiber intake (per 10 g per day) was associated with a lower risk of any complications (odds ratio [OR], 0.75; 95% CI, 0.62-0.92) and surgical complications (OR, 0.76; 95% CI, 0.60-0.97), whereas no association with anastomotic leakage was found (OR, 0.97; 95% CI, 0.66-1.43). Among women, higher dietary intake was associated with any complications (OR, 0.64; 95% CI, 0.44-0.94), whereas there was no association among men (OR, 0.79; 95% CI, 0.63-1.01). Fiber intake from vegetables (per 1 g per day) was inversely associated with any (OR, 0.90; 95% CI, 0.83-0.99) and surgical (OR, 0.87; 95% CI, 0.78-0.97) complications.

CONCLUSIONS AND RELEVANCE

In this cohort study, higher habitual dietary fiber intake before surgery was associated with a lower risk of postoperative complications among patients with colorectal cancer. The findings suggest that improving preoperative dietary fiber intake may be considered in future prehabilitation programs for patients undergoing surgery for colorectal cancer.

The Effect of Dietary Fibre on Gut Microbiota, Lipid Profile, and Inflammatory Markers in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Background: A disequilibrium of the gut microbial community has been closely associated with systemic inflammation and metabolic syndromes including type 2 diabetes. While low fibre and high fat diets may lead to dysbiosis of the gut microbiome as a result of the loss of useful microbes, it has been reported that a high fibre diet may prevent the fermentation of protein and may promote eubiosis of gut microbiota. Aim: This review aims to evaluate the effect of dietary fibre (DF) on gut microbiota, lipid profile, and inflammatory markers in patients with type 2 diabetes. Methods: The PRISMA framework was relied on to conduct this systematic review and meta-analysis. Searches were carried out using electronic databases and reference list of articles. Results: Eleven studies were included in the systematic review, while ten studies were included in the meta-analysis. The findings revealed five distinct areas including the effects of DF on (a) gut microbiota (122 participants); (b) lipopolysaccharides (LPS, 79 participants) and lipopolysaccharides binding protein (LBP, 81 participants); (c) lipid profile; (d) inflammatory markers; and (e) body mass index (BMI, 319 participants). The relative abundance of Bifidobacterium increased by 0.73 (95% CI: 0.57, 0.89) in the DF group in contrast to the control (p < 0.05). With respect to LPS, the level was lower in the DF group than the control and the difference was significant (p < 0.05). The standardised mean difference for LPS was −0.45 (95% CI: −0.90, −0.01) although the difference between the two groups in relation to LBP was not significant (p = 0.08) and the mean difference was 0.92 (95% CI: −0.12, 1.95). While there was a decrease of −1.05 (95% CI: −2.07, −0.02) with respect to total cholesterol (356 participants) in the DF group as compared with the control (p < 0.05), both groups were not significantly different (p > 0.05) in the other lipid parameters. The difference between the groups was significant (p < 0.05) in relation to C-reactive protein, and the mean difference was 0.43 (95% CI: 0.02, 0.84). This could be due to the short duration of the included studies and differences in participants’ diets including the amount of dietary fibre supplements. However, the groups were not significantly different (p > 0.05) with respect to the other inflammatory markers. The meta-analysis of the BMI showed that the DF group decreased by −0.57 (95% CI: −1.02, −0.12) as compared with the control and this was significant (p < 0.01). Conclusion: DF significantly (p < 0.05) increased the relative abundance of Bifidobacterium and significantly decreased (p < 0.05) LPS, total cholesterol, and BMI as compared with the control. However, DF did not seem to have an effect that was significant on LBP, triglyceride, HDL cholesterol, LDL cholesterol, IL-6, TNF-α, adiponectin, and leptin. These findings have implications for public health in relation to the use of dietary fibre in nutritional interventions and as strategies for managing type 2 diabetes.

Health beneficial effects of resistant starch on diabetes and obesity via regulation of gut microbiota: a review

Resistant starch (RS) is well known to prevent type 2 diabetes mellitus (T2DM) and obesity. Recently, attention has been paid to gut microbiota which mediates the RS's impact on T2DM and obesity, while a mechanistic understanding of how RS prevents T2DM and obesity through gut microbiota is not clear yet. Therefore, this review aims at exploring the underlying mechanisms of it. RS prevents T2DM and obesity through gut microbiota by modifying selective microbial composition to produce starch-degrading enzymes, promoting the production of intestinal metabolites, and improving gut barrier function. Therefore, RS possessing good functional features can be used to increase the fiber content of healthier food. Furthermore, achieving highly selective effects on gut microbiota based on the slight differences of RS's chemical structure and focusing on the effects of RS on strain-levels are essential to manipulate the microbiota for human health.

Nutritional Components in Western Diet Versus Mediterranean Diet at the Gut Microbiota-Immune System Interplay. Implications for Health and Disease

The most prevalent diseases of our time, non-communicable diseases (NCDs) (including obesity, type 2 diabetes, cardiovascular diseases and some types of cancer) are rising worldwide. All of them share the condition of an "inflammatory disorder", with impaired immune functions frequently caused or accompanied by alterations in gut microbiota. These multifactorial maladies also have in common malnutrition related to physiopathology. In this context, diet is the greatest modulator of immune system-microbiota crosstalk, and much interest, and new challenges, are arising in the area of precision nutrition as a way towards treatment and prevention. It is a fact that the westernized diet (WD) is partly responsible for the increased prevalence of NCDs, negatively affecting both gut microbiota and the immune system. Conversely, other nutritional approaches, such as Mediterranean diet (MD), positively influence immune system and gut microbiota, and is proposed not only as a potential tool in the clinical management of different disease conditions, but also for prevention and health promotion globally. Thus, the purpose of this review is to determine the regulatory role of nutritional components of WD and MD in the gut microbiota and immune system interplay, in order to understand, and create awareness of, the influence of diet over both key components.

Effects of Dietary Supplementation with High Fiber (Stevia Residue) on the Fecal Flora of Pregnant Sows

Simple Summary

This study aimed to investigate the effects of different supplementation levels of stevia residues in high-fiber diets on the fecal microorganisms of pregnant sows. Stevia residue supplementation significantly increased the abundance of beneficial bacteria, such as g__Lachnospiraceae_XPB1014_group, g__Christensenellaceae_R-7_group, and g__Ruminococcaceae_UCG-005 (p < 0.05), and significantly reduced the abundance of harmful bacteria, such as Treponema_2 (p < 0.05), at the genus level. The stevia-residue supplementation reduced the feed cost, with the highest reduction rate being 13.33%. In conclusion, high-fiber diets can improve the intestinal balance and evenness index of the intestinal flora in pregnant sows, promote the relative abundance of beneficial bacteria, reduce the relative abundance of harmful bacteria, and reduce feed cost.

Abstract

This study aimed to investigate the effects of different supplementation levels of stevia residues in high-fiber diets on the fecal microorganisms of pregnant sows. Forty-eight first-farrowing Danish Landrace sows with similar weight, age, and due date were randomly divided into four groups. The control group was fed a normal diet (CON; 3.15% crude fiber content), and the treatment groups were supplemented with 20% stevia residue (SRL), 30% stevia residue (SRM), or 40% stevia residue (SRH) stevia residue, with crude fiber content of 7.79%, 9.15%, and 10.68%, respectively. The test period was 135 days, and Illumina Miseq high-throughput sequencing was used to test the fecal bacteria of the pregnant sows on day 56. Compared to the control group, species diversity was greater in the 30% stevia residue group. At the phylum level, Firmicutes and Spirochaetes had the greatest relative abundances; Firmicutes was most abundant in the SRM group, and Spirochaetes was most abundant in the CON group. At the genus level, Lactobacillus, Streptococcus, and Lachnospiraceae_XPB1014_group, and Treponema_2 had the highest relative abundances in the stevia-residue treatments. Among them, Lactobacillus and Treponema_2 were more abundant in SRL, Streptococcus was more abundant in SRH, and Lachnospiraceae_XPB1014_group was more abundant in SRM. Linear discriminant analysis effect size (LEfSe) showed that the bacterial species differed among the stevia residue treatments. SRL mainly included g__Lactobacillus and g__Romboutsi, SRM mainly included g__Lachnospiraceae_XPB1014_group and g__Ruminococcaceae_UCG_014, SRH mainly included g__Streptococcus, and CON mainly included g__Treponema_2, f__Clostridiaceae_1, g__norank_f__Muribaculaceae, and g__norank_f__p_251_o5. Stevia-residue supplementation significantly increased the abundance of beneficial bacteria, such as g__Lachnospiraceae_XPB1014_group, g__Christensenellaceae_R-7_group, and g__Ruminococcaceae_UCG-005 (p < 0.05), and significantly reduced the abundance of harmful bacteria, such as Treponema_2 (p < 0.05). Moreover, compared with the control group, the stevia-residues treatment groups reduced the feed cost 8.33%, 12.50%, and 13.33% per sow per day, respectively. In conclusion, high-fiber diets can improve the intestinal balance and evenness index of the intestinal flora in pregnant sows, promote the relative abundance of beneficial bacteria, reduce the relative abundance of harmful bacteria, and reduce feed cost. The optimal supplementation level of the stevia residue was found to be 30%.

Bioactive Components and Health Beneficial Properties of Whole Wheat Foods

Epidemiological studies have found that whole wheat consumption is inversely associated with the risk of chronic diseases, such as obesity, type 2 diabetes, cardiovascular diseases, and cancer. The health benefits of whole wheat foods are attributed to their bioactive components, including phytochemicals and dietary fiber. In this review, the current studies regarding bioactive components and their health-promoting roles and the underlying mechanisms were summarized and discussed. The current research advances in processing technologies capable of potentially enhancing the nutritional quality of wheat and wheat-based foods were also included. This review may promote the research, development, and consumption of whole wheat foods in reducing the risk of human chronic diseases.

Dietary Acid Load and Cardiometabolic Risk Factors-A Narrative Review

The Western, diet rich in acidogenic foods (e.g., meat, fish and cheese) and low in alkaline foods (e.g., vegetables, fruits and legumes), is deemed to be a cause of endogenous acid production and elevated dietary acid load (DAL), which is a potential cause of metabolic acidosis. Multiple authors have suggested that such a dietary pattern increases the excretion of calcium and magnesium, as well as cortisol secretion. In addition, it is associated with decreased citrate excretion. All of these seem to increase blood pressure and insulin resistance and may contribute to the development of cardiometabolic disorders. However, there are inconsistencies in the results of the studies conducted. Therefore, this narrative literature review aims to present the outcomes of studies performed in recent years that investigated the association between DAL and the following cardiometabolic risk factors: blood pressure, hypertension, carbohydrate metabolism and lipid profile. Study outcomes are divided into (i) statistically significant positive association, (ii) statistically significant inverse association, and (iii) no statistically significant association.

The Role of Dietary Fibre in Modulating Gut Microbiota Dysbiosis in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Background: The prevalence of type 2 diabetes is on the increase worldwide, and it represents about 90% of adults who are diagnosed with diabetes. Overweight and obesity, lifestyle, genetic predisposition and gut microbiota dysbiosis have been implicated as possible risk factors in the development of type 2 diabetes. In particular, low intake of dietary fibre and consumption of foods high in fat and sugar, which are common in western lifestyle, have been reported to contribute to the depletion of specific bacterial taxa. Therefore, it is possible that intake of high dietary fibre may alter the environment in the gut and provide the needed substrate for microbial bloom. Aim: The current review is a systematic review and meta-analysis which evaluated the role of dietary fibre in modulating gut microbiota dysbiosis in patients with type 2 diabetes. Methods: This is a systematic review and meta-analysis of randomised controlled trials which relied on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework. Electronic searches were conducted using EBSCOHost with links to Health Sciences Research Databases, EMBASE and Google Scholar. The reference lists of articles were also searched for relevant studies. Searches were conducted from date of commencement of the database to 5 August 2020. The search strategy was based on the Population, Intervention, Comparator, Outcomes, Studies (PICOS) framework and involved the use of synonyms and medical subject headings (MesH). Search terms were combined with Boolean operators (OR/AND). Results: Nine studies which met the inclusion criteria were selected for the systematic review and meta-analysis, and four distinct areas were identified: the effect of dietary fibre on gut microbiota; the role of dietary fibre on short-chain fatty acids (SCFAs); glycaemic control; and adverse events. There was significant difference (p < 0.01) in the relative abundance of Bifidobacterium with a mean difference of 0.72 (95% CI, 0.56, 0.89) between the dietary fibre group compared with placebo. In relation to the meta-analysis for SCFAs, while there was significant difference (p = 0.02) between the dietary fibre group and placebo with a standardised mean difference of 0.5 (95% CI, 0.08, 0.91) regarding total SCFAs, the differences were not significant (p > 0.05) in relation to acetic acid, propionic acid and butyric acid. There was only significant improvement (p = 0.002) with respect to glycated haemoglobin with a mean difference of −0.18 (95% CI, −0.29, −0.06) between the dietary fibre group and placebo group. Differences between the two groups were not significant (p > 0.05) in relation to fasting blood glucose and homeostatic model assessment of insulin resistance (HOMA-IR). Furthermore, there were no significant differences between the two groups in subjects who reported adverse events. It is possible that the promotion of SCFA producers in greater diversity and abundance by dietary fibre in this review led to improvement in glycated haemoglobin, partly due to increased glucagon-like peptide-1 (GLP-1) production. In addition, Bifidobacterium lactis has been reported to increase glycogen synthesis, decrease expression of hepatic gluconeogenesis genes, improve translocation of glucose transport-4 and promote glucose uptake. It is also possible that the reduction in body weight of participants in the intervention group compared with control may have contributed to the observed improvement in glycated haemoglobin. Conclusion: This systematic review and meta-analysis have demonstrated that dietary fibre can significantly improve (p < 0.05) the relative abundance of Bifidobacterium, total SCFAs and glycated haemoglobin. However, dietary fibre did not appear to have significant effect (p > 0.05) on fasting blood glucose, HOMA-IR, acetic acid, propionic acid, butyric acid and adverse events.

Physicochemical, Sensory, and Cooking Qualities of Pasta Enriched with Oat β-Glucans, Xanthan Gum, and Vital Gluten

The functional properties of β-glucans derived from oats and barley are confirmed by numerous in vitro and in vivo studies. This study aimed to assess the effect of adding 0, 5, 10, 15, and 20% oat (1,3)(1,4)-β-D-glucans to physicochemical properties, as well as the cooking and sensory qualities of durum wheat pasta. Additionally, to improve the cooking and sensory qualities of pasta, we added 5% of xanthan gum and vital gluten. The present study showed that the addition of β-glucans led to an increase of the water absorption index (WAI), water solubility index (WSI), and viscosity of products. At the same time, an increase in the content of fat, ash, and dietary fiber was observed. The addition of (1,3)(1,4)-β-D-glucans influenced the cooking quality of the pasta, extending the minimum cooking time and increasing the loss of dry matter. At the same time, the color of the product changed. In the case of cooked pasta, the addition of β-glucans decreased the brightness and increased the yellowness and redness. It was found that the products enriched with 10–15% of β-glucans, as well as 5% of xanthan gum and vital gluten would yield functional pasta that may offer health benefits beyond its nutritional value. Further, this could influence high cooking and sensory quality.

Dietary Fibre from Whole Grains and Their Benefits on Metabolic Health

The consumption of whole grain products is often related to beneficial effects on consumer health. Dietary fibre is an important component present in whole grains and is believed to be (at least partially) responsible for these health benefits. The dietary fibre composition of whole grains is very distinct over different grains. Whole grains of cereals and pseudo-cereals are rich in both soluble and insoluble functional dietary fibre that can be largely classified as e.g., cellulose, arabinoxylan, β-glucan, xyloglucan and fructan. However, even though the health benefits associated with the consumption of dietary fibre are well known to scientists, producers and consumers, the consumption of dietary fibre and whole grains around the world is substantially lower than the recommended levels. This review will discuss the types of dietary fibre commonly found in cereals and pseudo-cereals, their nutritional significance and health benefits observed in animal and human studies.

Effects of a ready-to-eat cereal formula powder on glucose metabolism, inflammation, and gut microbiota in diabetic db/db mice

The cereal formula powder, Zhengda Jingshan (ZDJS), comprises dietary fiber, multivitamins, fine protein, and various cereal ingredients. The present study evaluated the effects of ZDJS on glucose metabolism and explored the corresponding mechanisms in terms of modulating gut microbiota and the fecal metabolome. Type 2 diabetic db/db mice were given ZDJS (1 g/kg) orally twice daily for 55 days, after which glucose metabolism, inflammation, gut microbiota, and fecal metabolomics were assayed. Repeated administration of ZDJS was associated with a trend toward decreasing fasting blood glucose and a 0.12% decrease in hemoglobin A1c (HbA1c), as well as statistically significant increases in the insulin sensitivity index and decreases in serum levels of tumor necrosis factor (TNF-α) and ileum expression of mucin-2. ZDJS also ameliorated the compensatory enlargement of islets and decreased the ratio of the α-cell area to total islet area; however, this amelioration of impaired oral glucose tolerance became less pronounced as treatment continued. In addition, ZDJS remarkably decreased the abundance of phylum Proteobacteria and the phylum ratio of Firmicutes to Bacteroidetes, as well as altered the fecal metabolic profile. Taken together, our findings demonstrate that ZDJS improved glucose metabolism and reduced inflammation in type 2 diabetic db/db mice, which may be associated with a reshaping of the gut microbiome and fecal metabolome in db/db mice. Thus, our study suggests that ZDJS may represent a complementary therapy for patients with type 2 diabetes.

Carbohydrate quality, glycemic index, glycemic load and cardiometabolic risks in the US, Europe and Asia: A dose-response meta-analysis

BACKGROUND AND AIMS

Despite the proven evidence of high glycemic index (GI) and glycemic load (GL) diets to increase cardiometabolic risks, knowledge about the meta-evidence for carbohydrate quality within world geographic regions is limited. We conducted a meta-analysis to synthesize the evidence of GI/GL studies and carbohydrate quality, gathering additional exposures for carbohydrate, high glycemic carbohydrate, total dietary fiber, and cereal fiber and risks for type 2 diabetes (T2DM), coronary heart disease (CHD), stroke, and mortality, grouped into the US, Europe, and Asia. Secondary aims examined cardiometabolic risks in overweight/obese individuals, by sex, and dose-response dietary variable trends.

METHODS AND RESULTS

40-prospective observational studies from 4-Medline bibliographical databases (Ovid, PubMed, EBSCOhost, CINAHL) were search up to November 2019. Random-effects hazard ratios (HR) and 95% confidence intervals (CI) for highest vs. lowest categories and continuous form combined were reported. Heterogeneity (I²>50%) was frequent in US GI/GL studies due to differing study characteristics. Increased risks ((HR_GI,T2DM,US=1.14;CI:1.06,1.21), HR_GL,T2DM,US=1.02 (1.01, 1.03)), HR_GI,T2DM,Asia=1.25;1.02,1.53), and HR_GL,T2DM,Asia=1.37 (1.17, 1.60)) were associated with cardiometabolic diseases. GI/GL in overweight/obese females had the strongest magnitude of risks in US-and Asian studies. Total dietary fiber (HR_T2DM,US = 0.92;0.88,0.96) and cereal fiber (HR_T2DM,US = 0.83;0.77,0.90) decreased risk of developing T2DM. Among females, we found protective dose-response risks for total dietary fiber (HR_{5g-total-dietary-fiber,T2DM,US} = 0.94;0.92,0.97)_, but cereal fiber showed better ability to lower T2DM risk (HR_{5g-cereal-fiber},_T2DM,US = 0.67;0.60,0.74). Total dietary-and cereal fibers' dose-response effects were nullified by GL, but not so for cereal fiber with GI.

CONCLUSIONS

Overweight/obese females could shift their carbohydrate intake for higher cereal fiber to decrease T2DM risk, but higher GL may cancel-out this effect.

Hypocaloric, plant-based oatmeal interventions in the treatment of poorly-controlled type 2 diabetes: A review

BACKGROUND

Lifestyle interventions, including dietary modifications, play a key role in the treatment of type 2 diabetes. By the second half of the last century, dietary oatmeal interventions had frequently been used in patients with diabetes; however, with the widespread introduction of insulin, this practice gradually fell into disuse. Within the last decades, the original oatmeal intervention, first described in 1903, has been modified towards a hypocaloric, low-fat, and plant-based intervention.

AIM

The aim of this review was to investigate the current role of these adapted short-term dietary oatmeal interventions in the treatment of patients suffering from poorly-controlled type 2 diabetes. A special focus was put on opportunities for and barriers to its clinical implementation and its potential mechanisms of action.

METHODS

The electronic databases of PubMed and Google Scholar were searched using the keywords "oat," "oats," "oatmeal," and "diabetes."

RESULTS

While there are a limited number of clinical studies including hypocaloric short-term dietary oatmeal interventions, there is evidence that these interventions may lead to a significant decrease in mean blood glucose levels and a significant reduction of insulin dosage in patients suffering from poorly-controlled type 2 diabetes.

CONCLUSION

Modified short-term dietary oatmeal interventions are an effective and economical tool in the treatment of patients suffering from poorly-controlled type 2 diabetes.

Effects of insoluble and soluble fibers isolated from barley on blood glucose, serum lipids, liver function and caecal short-chain fatty acids in type 2 diabetic and normal rats

Large prospective cohort studies suggested an important role of cereal insoluble fiber in the prevention and management of type 2 diabetes, which challenge the traditional view that viscosity and solubility are the main driving factors for these beneficial effects of dietary fiber. To evaluate the anti-diabetic effects of insoluble- (BIF) and soluble fibers (BSF) enzymatically isolated from barley, a conventional rat model and a type 2 diabetes rat model were used. Our results showed that 4-week treatment of BIF or BSF effectively reduced FBG in the diabetic condition, with caecal level of propionic acid and minor SCFAs increased by BIF and that of butyric acid and insulin sensitivity improved by BSF, respectively. The two treatments further ameliorated liver function, judged by the recovered serum level of ALT, albumin and total protein levels. BIF and BSF also increased HDL-C and decreased serum MDA. In normal rats, BIF and BSF showed a hypolipidaemic effect in triglycerides and LDL-C, reduced body weight and enhanced the caecal production of minor SCFAs. Furthermore, the two treatments reduced the caecal level of butyric acid while BSF increased that of propionic acid. In conclusion, BIF could exert anti-diabetic effects that might via a different mechanism from BSF.

Functional Cereal Products in the Diet for Type 2 Diabetes Patients

Type 2 diabetes has become one of the major health problems of the modern world. It is assumed that environmental factors have a significant impact on the development of the disease, and great importance is ascribed to the diet, which can be modified accordingly. The diet can exert prophylactic and therapeutic effects; changes in the diet in advanced disease can improve the quality of life of diabetic patients and minimise the risk of complications, which are the direct cause of diabetes-related death. Functional food, which has a potentially health-enhancing effect in addition to its nutritional value, has been increasingly recognised and required. Cereal products are crucial in diabetic nutrition. Their function can additionally be enhanced by fortification with compounds with proven hypoglycaemic effects. Pasta has a low glycaemic index and is a good carrier of fortifying substances; hence, it can be highly recommended in diets for diabetic patients.

Dietary Approaches to Stop Hypertension (DASH): potential mechanisms of action against risk factors of the metabolic syndrome

The metabolic syndrome is a cluster of disorders dominated by abdominal obesity, hypertriacylglycerolaemia, low HDL-cholesterol, high blood pressure and high fasting glucose. Diet modification is a safe and effective way to treat the metabolic syndrome. Dietary Approaches to Stop Hypertension (DASH) is a dietary pattern rich in fruits, vegetables and low-fat dairy products, and low in meats and sweets. DASH provides good amounts of fibre, K, Ca and Mg, and limited quantities of total fat, saturated fat, cholesterol and Na. Although DASH was initially designed for the prevention or control of hypertension, using a DASH diet has other metabolic benefits. In the present review, the effect of each dietary component of DASH on the risk factors of the metabolic syndrome is discussed. Due to limited fat and high fibre and Ca content, individuals on the DASH diet are less prone to overweight and obesity and possess lower concentrations of total and LDL-cholesterol although changes in TAG and HDL-cholesterol have been less significant and available evidence in this regard is still inconclusive. Moreover, high amounts of fruit and vegetables in DASH provide great quantities of K, Mg and fibre, all of which have been shown to reduce blood pressure. K, Mg, fibre and antioxidants have also been effective in correcting glucose and insulin abnormalities. Evidence is provided from cross-sectional investigations, cohort studies and randomised controlled trials, and, where available, from published meta-analyses. Mechanisms are described according to human studies and, in the case of a lack of evidence, from animal and cell culture investigations.

Association Between Okinawan Vegetables Consumption and Risk of Type 2 Diabetes in Japanese Communities: The JPHC Study

Background

Some Okinawan vegetables have been reported to have anti-diabetic activity; however, no prospective cohort study has clarified whether consumption of Okinawan vegetables is associated with a risk of type 2 diabetes. This study aimed to determine the association between consumption of Okinawan vegetables and risk of type 2 diabetes through a large-scale, population-based, prospective study in Japan.

Methods

We examined 10,732 participants (4,714 men and 6,018 women) aged 45–74 years who resided in Okinawa. Participants were asked to answer a 147-item food frequency questionnaire. We calculated the overall amount of Okinawan vegetables consumed and the amount of seven specific kinds of Okinawan vegetables consumed. The odds ratios (ORs) for self-reported type 2 diabetes during 5 years of follow-up were estimated via multivariate logistic regression analysis.

Results

During the 5-year period, 216 new cases (123 men and 93 women) of type 2 diabetes were reported. Comparing the highest tertile to the lowest tertile of intake, the overall amount of Okinawan vegetables consumed was not associated with risk of type 2 diabetes in men (OR 1.22; 95% confidence interval [CI], 0.74–2.01, P-trend = 0.53) or in women (OR 0.96; 95% CI, 0.57–1.62, P-trend = 0.89). The consumption of seven specific kinds of Okinawan vegetables was also not associated with the risk of type 2 diabetes.

Conclusions

The consumption of total Okinawan vegetables was not associated with the risk of type 2 diabetes.

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 sources and human benefits: The case study of cereal and pseudocereals

Dietary fiber (DF) includes the remnants of the edible part of plants and analogous carbohydrates that are resistant to digestion and absorption in the human small intestine with complete or partial fermentation in the human large intestine. DF can be classified into two main groups according to its solubility, namely insoluble dietary fiber (IDF) that mainly consists on cell wall components, including cellulose, some hemicelluloses, lignin and resistant starch, and soluble dietary fiber (SDF) that consists of non-cellulosic polysaccharides as non-digestible oligosaccharides, arabinoxylans (AX), β-glucans, some hemicelluloses, pectins, gums, mucilages and inulin. The intake of DF is associated with health benefits. IDF can contribute to the normal function of the intestinal tract and it has an important role in the prevention of colonic diverticulosis and constipation. SDF is extensively fermented by gut microbiota and it is associated with carbohydrate and lipid metabolism, with important health benefits due to its hypocholesterolemic properties. Due to these nutritional and health properties, DF is widely used as functional ingredients in food industry, being whole grain cereals, pulses, fruits and vegetables the main sources of DF. Also some synthetic sources are employed, namely polydextrose, hydroxypropyl methylcellulose or cyclodextrins. The DF content of cereals varies depending on cultivars, their botanical components (pericarp, emdosperm and germ) and the processing conditions they have undergone (baking, extrusion, etc.). In cereal grains, AX are the predominant non-cellulose DF polysaccharides followed by cellulose and β-glucans, while in pseudocereals, pectins are quantitatively predominant.

Dietary fibers as emerging nutritional factors against diabetes: focus on the involvement of gut microbiota

Diabetes mellitus (DM) increases the risk of cardiovascular diseases and other secondary complications, such as nephropathy, neuropathy, retinopathy, etc. The important risk factors for the pathogenesis of DM are aging, family history, sedentary lifestyle, unhealthy dietary habits, and obesity. Evidence from epidemiological studies also indicates that DM is characterized by specific alterations in the human gut microbiota (GM). GM transplantation in rodents and humans revealed that a specific GM constituent can be the cause and not just the consequence of the DM condition and complications. These findings suggest a potential role of GM in human health, disease prevention, and treatment. Dietary intervention studies using dietary fibers (DFs) suggested that modulation of the GM can suppress the metabolic risk markers in humans. However, a causal role of GM in such studies remains unexplored. Long-term follow-up studies disclosed that the diet rich in insoluble and non-viscous fibers are responsible for DF-mediated antidiabetic activities, while soluble and viscous fibers have little influence on DM despite having a profound impact on glycemia. However, general conclusions cannot be drawn simply based on these findings. Long-term follow-up studies are urgently required in this area to explore the therapeutic potential of different DFs in treating DM and to delineate the exact role of GM involvement. Here we review and discuss the signature of GM during DM, antidiabetic activity of metformin via GM modulation, DFs from different sources and their antidiabetic activity, and the possible role of GM involvement.