Oat gum lowers glucose and insulin after an oral glucose load

The importance of molecular weight in determining the minimum dose of oat β-glucan required to reduce the glycaemic response in healthy subjects without diabetes: a systematic review and meta-regression analysis

To determine the minimum amount of oat β-glucan (OBG) required to reduce glycaemic responses (MinDose), we conducted a systematic review and meta-regression analysis of acute, crossover, single-meal feeding trials that examined the effects of adding OBG or oat bran to a carbohydrate-containing test-meal versus a control test-meal containing an equivalent amount of available-carbohydrate (avCHO) from the same or similar source. Medline, Embase, and Cochrane Library were searched up to 18 August 2021. The primary outcome was glucose incremental-area-under-the-curve (iAUC). Secondary outcomes included insulin iAUC, and glucose and insulin incremental peak-rise (iPeak). Two independent reviewers extracted data. Results were expressed as ratio-of-means (RoM) with 95% confidence intervals (CIs). Linear associations were assessed by random effects meta-regression. MinDose was defined as the dose at which the upper 95% CI of the regression line cut the line of no effect (i.e., RoM = 1). Fifty-nine comparisons (n = 340) were included; 57 in healthy subjects without diabetes and two in subjects with diabetes; 24 high-MW (>1000 kg/mol), 22 medium-MW (300-1,000 kg/mol), and 13 low-MW (<300 kg/mol). In healthy subjects without diabetes the associations between OBG dose and glucose iAUC and iPeak were linear (non-linear p value >0.05). MinDoses for glucose iAUC for high-MW, medium-MW and low-MW OBG, respectively, were estimated to be 0.2 g, 2.2 g and 3.2 g per 30 g avCHO; MinDoses for glucose iPeak were less than those for iAUC. Insufficient data were available to assess MinDose for insulin, however, there was no evidence of a disproportionate increase in insulin. More high-quality trials are needed to establish MinDose in individuals with diabetes.

Study of Selected Beverages with Β-Glucan from Oats and Barley on Physical Properties, Sensory Perception, Glycemic Index and Satiety

Over recent years, more and more products with β-glucan have appeared in the market. This study was conducted to determine the physical, sensory evaluation and glycemic index (GI) of selected popular beverages with β-glucan in the Malaysian market, which were Biogrow Oat BG22 (from oats) and Biolife Barley BG25 (from barley). The physical parameters measured were colour, viscosity, and total suspended solid. Sensory analysis was conducted on 30 subjects using the 7-point hedonic scale. Attributes assessed were colour, aroma, viscosity, sweetness and overall acceptance. A total of 10 subjects were involved in the determination of GI value of these beverages. A total of 25 g glucose was used as the reference. Test meals also contained 25 g available carbohydrate and all beverages were mixed with 250 mL water. Blood samples (finger prick) were taken every 15 minutes (first hour) and 30 minutes (second hour) for the duration of 120 minutes after the food sample consumption. Test protocol was based on ISO26642:2010. Blood glucose values were determined using glucometer. A total of 30 subjects were chosen for the determination of satiety scores. Labelled magnitude satiety scale was used to measure satiety scores before and after test beverage consumption. Subjects were required to assess their perception of fullness or hunger by marking on the labelled magnitude satiety scale every 15 minutes for the first hour and 30 minutes for subsequent 2 hour for a total of 180 minutes. The colour analysis showed that BG25 and BG22 were slightly yellow due to positive b* value. The BG22 was more viscous and do not contain any sugar compared to BG25. Blood glucose level after glucose intake reached optimum level (9.9 mmol/L) at 30 minutes while BG25 and BG22 reached optimum level at 45 minutes with the value 7.9 mmol/L and 6.4 mmol/L respectively. Significant difference was found for attributes aroma, viscosity and overall acceptance of the two products. Our study found, BG22 from oats were has better physical attributes and is better accepted by the panelists. However, it is suggested that both products be taken together with milk or soy to improve the taste. The GI for BG25 was 79 (high GI) while BG22 was 32 (low GI). The BG22 with lower GI is significantly more satiating than BG25 and perhaps can be a choice of beverage for people who are managing diabetes and obesity.

A Review of Health-Beneficial Properties of Oats

Oat is among the food crops and ancient grains cultivated and consumed worldwide. It is gaining in popularity owing to its nutritional composition and multifunctional benefits of select bioactive compounds. Beta-glucan is an important component of dietary fiber found in oat grains. It is the major active compound in oats with proven cholesterol-lowering and antidiabetic effects. Oats also provide substantial levels of other bioactive compounds such as phenolic acids, tocols, sterols, avenacosides, and avenanthramides. The consumption of oats has been determined to be beneficial for human health by promoting immunomodulation and improving gut microbiota. In addition, oat consumption assists in preventing diseases such as atherosclerosis, dermatitis, and some forms of cancer. While much has been published in relation to oat nutrients and oat fibers and their impact on major diseases, the oat industries and consumers may benefit from greater knowledge and understanding of clinical effects, range of occurrence, distribution, therapeutic doses and food functional attributes of other oat bioactives such as avenanthramides and saponins as well as other anti-inflammatory agents found in the cereal. This review focuses on the various studies relevant to the contribution of the consumption of oats and oat-based products in preventing human diseases and promoting human health.

Ancient grains as novel dietary carbohydrate sources in canine diets

Ancient grains are becoming an increasingly abundant carbohydrate source in the pet food market as a result of their popularity and novelty in the human market. Thus, it is imperative to evaluate the characteristics of these ingredients in vivo. Ten adult intact female beagles were used in a replicated 5 × 5 Latin square design. Five dietary treatments were evaluated containing either: rice (CON), amaranth (AM), white proso millet (WPM), quinoa (QU), or oat groats (OG). All diets were formulated to include 40% of the test grain and to be isonitrogenous, isocaloric, and nutritionally complete and balanced for adult dogs at maintenance. The objectives were 1) to evaluate the effects of the novel carbohydrate sources on total apparent total tract digestibility (ATTD), fecal microbiota, and fermentative end-product concentrations and 2) to evaluate the effects of novel carbohydrate sources on the postprandial glycemic and insulinemic responses in healthy adult dogs. All diets were well accepted by the dogs and fecal scores remained within the ideal range for all treatments. In terms of ATTD, all diets were well digested by the dogs; WPM had the highest digestibility of dry and organic matter in contrast with dogs fed the other treatments (P < 0.05). Additionally, ATTD of total dietary fiber was highest for WPM (72.6%) in contrast with QU (63.5%) and CON (50.8%) but did not differ from AM (65.7%) and OG (66.6%). Dogs fed AM or OG had greater (P < 0.05) fecal concentrations of total short-chain fatty acids, as well as propionate and butyrate concentrations, than CON. Ancient grain inclusion appears to beneficially shift fecal microbial populations, with increases in relative abundances of butyrogenic bacteria (i.e., members of the Lachnospiraceae family) observed for OG and reductions in Fusobacteriaceae for both AM and OG when compared with CON. Postprandial glycemic and insulinemic responses did not differ among treatments. Together, these data suggest that ancient grains can be included up to 40% of the diet while eliciting beneficial effects on the overall host health without detrimentally affecting nutrient digestibility.

The effect of oat β-glucan on postprandial blood glucose and insulin responses: a systematic review and meta-analysis

To determine the effect of oat β‑glucan (OBG) on acute glucose and insulin responses and identify significant effect modifiers we searched the MEDLINE, EMBASE, and Cochrane databases through October 27, 2020 for acute, crossover, controlled feeding trials investigating the effect of adding OBG (concentrate or oat-bran) to carbohydrate-containing test-meals compared to comparable or different carbohydrate-matched control-meals in humans regardless of health status. The primary outcome was glucose incremental area-under-the-curve (iAUC). Secondary outcomes were insulin iAUC, and glucose and insulin incremental peak-rise (iPeak). Two reviewers extracted the data and assessed risk-of-bias and certainty-of-evidence (GRADE). Data were pooled using generic inverse-variance with random-effects model and expressed as ratio-of-means with [95% CIs]. We included 103 trial comparisons (N = 538). OBG reduced glucose iAUC and iPeak by 23% (0.77 [0.74, 0.81]) and 28% (0.72 [0.64, 0.76]) and insulin by 22% (0.78 [0.72, 0.85]) and 24% (0.76 [0.65, 0.88]), respectively. Dose, molecular-weight, and comparator were significant effect modifiers of glucose iAUC and iPeak. Significant linear dose-response relationships were observed for all outcomes. OBG molecular-weight >300 kg/mol significantly reduced glucose iAUC and iPeak, whereas molecular-weight <300 kg/mol did not. Reductions in glucose iAUC (27 vs 20%, p = 0.03) and iPeak (39 vs 25%, p < 0.01) were significantly larger with different vs comparable control-meals. Outcomes were similar in participants with and without diabetes. All outcomes had high certainty-of-evidence. In conclusion, current evidence indicates that adding OBG to carbohydrate-containing meals reduces glycaemic and insulinaemic responses. However, the magnitude of glucose reduction depends on OBG dose, molecular-weight, and the comparator.

GUT Microbiome-GUT Dysbiosis-Arterial Hypertension: New Horizons

Arterial hypertension is a progressive cardiovascular syndrome arising from complex and interrelated etiologies. The human microbiome refers to the community of microorganisms that live in or on the human body. They influence human physiology by interfering in several processes such as providing nutrients and vitamins in Phase I and Phase II drug metabolism. The human gut microbiota is represented mainly by Firmicutes and Bacteroidetes and to a lesser degree by Actinobacteria and Proteobacteria, with each individual harbouring at least 160 such species. Gut microbiota contributes to blood pressure homeostasis and the pathogenesis of arterial hypertension through production, modification, and degradation of a variety of microbial-derived bioactive metabolites. Animal studies and to a lesser degree human research has unmasked relative mechanisms, mainly through the effect of certain microbiome metabolites and their receptors, outlining this relationship. Interventions to utilize these pathways, with probiotics, prebiotics, antibiotics and fecal microbiome transplantation have shown promising results. Personalized microbiome-based disease prediction and treatment responsiveness seem futuristic. Undoubtedly, a long way of experimental and clinical research should be pursued to elucidate this novel, intriguing and very promising horizon.

Unravelling the Effects of Soluble Dietary Fibre Supplementation on Energy Intake and Perceived Satiety in Healthy Adults: Evidence from Systematic Review and Meta-Analysis of Randomised-Controlled Trials

Consumption of soluble dietary fibre is recommended as part of a healthy diet. Evidence has shown that soluble dietary fibre slows gastric emptying, increases perceived satiety and plays a significant role in appetite regulation. This systematic review examined the effects of soluble dietary fibre using randomised-controlled trials (RCTs). Three different electronic databases were used, namely PubMed, Scopus® and the Cochrane Central Register of Controlled Trials (CENTRAL). Effect size (Cohen's d) was calculated based on the intergroup mean difference and standard deviation (SD) followed by Cochran's Q and I² determination. The effect size was statistically pooled in the meta-analyses and presented as a forest plot. The risk of bias was high for each study as assessed using the Jadad scale. Meta-analysis of statistically pooled data for guar gum showed a sizeable effect on post-meal energy intake, followed by β-glucan, alginate, polydextrose and pectin, with pooled effect sizes of -0.90, -0.44, -0.42, -0.36 and -0.26, respectively. Guar gum (5 g) effectively reduced energy intake when prepared in milk beverages compared with control milk (p < 0.001). Alginate, when prepared in liquid (5 g) or solid (9 g) meals, effectively reduced energy intake compared with control (p < 0.001). A high dose of polydextrose (25 g) prepared in liquid meal form significantly reduced energy intake (p = 0.01). This study suggests that soluble fibres are not all created equal. Further interventional studies are needed to determine whether combinations of these soluble fibres might have greater effects than individual fibres per se.

A proof-of-concept study to evaluate the efficacy and safety of BTI320 on post-prandial hyperglycaemia in Chinese subjects with pre-diabetes

BACKGROUND

Galactomannan(s) are plant-derived fiber shown to reduce post-prandial blood glucose by delaying intestinal absorption of carbohydrates and slowing down gastric emptying. We examined glucose-lowering effects of BTI320, a propriety fractionated mannan(s) administered as a chewable tablet before meal in a proof-of-concept study in Chinese subjects with prediabetes.

METHODS

Sixty Chinese adults aged 18-70 years with either impaired fasting glucose, impaired glucose tolerance, or glycated haemoglobin 5.7-6.4% (39-46 mmol/mol), were randomly assigned in 2:2:1 ratio to either BTI320 8 g (high dose), BTI320 4 g (low dose) or matching-placebo three times daily before meal for 16 weeks. The primary endpoint was change in fructosamine in subjects treated with BTI320 compared with placebo from baseline to week 4. Indices of glycaemic variability based on continuous glucose monitoring (CGM) and standard meal tolerance test were explored in secondary analyses.

RESULTS

Of 60 subjects randomized, 3 subjects discontinued study treatment prematurely. In intention-to-treat analysis, no significant differences in change in serum fructosamine between low or high dose BTI320 and placebo were observed. Using random effect models, adjusted for variability by meals, treatment with low dose BTI320 was associated with reduction in 1-h (p < 0.01), 2-h (p = 0.01) and 3-h (p = 0.02) post-prandial incremental glucose area-under-curve and post-meal maximum glucose (p = 0.03) compared with placebo. Subjects receiving low dose BTI320 had greater body weight reduction than placebo group.

CONCLUSIONS

BTI320 did not change fructosamine levels compared with placebo. BTI320 reduced glycaemic variability based on CGM indices.

TRIAL REGISTRATION

The study was registered at www.clinicaltrials.gov , reference number NCT02358668 (9 February 2015).

The gut microbiome and hypertension

PURPOSE OF REVIEW

The mammalian mucosal surfaces are densely inhabited by a diverse microbial ecosystem termed the microbiota. Among these highly heterogeneous populations, the largest and richest is the gut microbiota, recently suggested to affect various physiological traits and susceptibility to disease. Novel metagenomic and metabolomic approaches, which have been developed in the past decade, have enabled the elucidation of the contribution of the microbiota to metabolic, immunologic, neurologic and endocrine homeostasis.

RECENT FINDINGS

Dysbiosis, the alteration in the gut microbiota composition and function, has been lately associated with the pathogenesis of multifactorial diseases such as obesity, diabetes and cardiovascular disorders. Recent studies have also suggested associations between dysbiosis and essential hypertension, a common chronic medical condition affecting 20% or more of the adult population worldwide, which is considered a major causative factor for heart disease, stroke, chronic renal failure, blindness and dementia.

SUMMARY

In this review, we discuss the accumulating research pointing to possible interplays between the gut microbiome and hypertension and highlight future prospects by which utilization of microbiome-related techniques may be incorporated into the diagnosis and therapeutic arsenal of hypertension management.

Effect of adding oat bran to instant oatmeal on glycaemic response in humans - a study to establish the minimum effective dose of oat β-glucan

Reducing the glycaemic response to carbohydrate-containing foods may have desirable physiological effects for many people. Here, we aimed to determine the minimum amount of oat β-glucan from oat-bran which, when added to instant-oatmeal, would reduce the glycaemic response by 20% compared to a β-glucan-free cereal. Therefore, the glycaemic responses elicited by one serving (27 g) instant-oatmeal plus 247 g 2% milk (IO, 28 g available-carbohydrate, 1.2 g β-glucan) or IO plus 0.2, 0.4, 0.8 or 1.6 g oat β-glucan (OBG) from oat-bran, or an available-carbohydrate matched portion of cream of rice (CR) plus milk were measured over 2 h in n = 40 subjects using a randomized, cross-over design. The primary endpoint was incremental area under the curve (iAUC). The secondary endpoint was glucose peak-rise. The results showed that grams OBG consumed were significantly correlated with mean iAUC (p = 0.009) and with mean glucose peak-rise (p = 0.002). Each gram of OBG reduced iAUC by 7% and peak-rise by 15%. Thus, to achieve a ≥20% reduction in iAUC relative to CR, 1.6 g OBG had to be added to IO (74 ± 7 vs. 93 ± 6 mmol min L^-1, p < 0.05), but, to achieve a 20% reduction in peak-rise, only 0.4 g OBG was required (2.00 ± 0.1 vs. 2.40 ± 0.1 mmol, p < 0.05). We conclude that adding OBG to IO flattened postprandial glycaemic responses in a dose-dependent fashion; 1.6 g OBG was required to reduce iAUC by ≥20% versus CR, but a 20% reduction in peak-rise required only 0.4 g. The greater effect of OGB on peak-rise than iAUC presumably reflects the way viscous dietary fibres modulate glucose absorption kinetics.

Comparative Analysis of Nutritional and Bioactive Properties of Aerial Parts of Snake Gourd (Trichosanthes cucumerina Linn.)

The present investigation was carried out to determine the nutritional and functional properties of T. cucumerina. Water extracts of freeze dried flowers, fruits, and leaves of T. cucumerina were evaluated for their total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity, α-amylase inhibitory activity, and fiber and mineral contents. Antioxidant activity, TPC, and TFC were significantly higher (P ≤ 0.05) in leaves than in flowers and fruits. A significant linear correlation was observed between the TPC, TFC, and antioxidant activities of plant extracts. Although, leaves and flower samples showed a significantly higher (P ≤ 0.05) amylase inhibitory activity than the fruit samples, the overall amylase inhibition was low in all three parts of T. cucumerina. Soluble and insoluble dietary fiber contents were significantly higher (P ≤ 0.05) in fruits than in flowers and leaves. Ca and K contents were significantly higher (P ≤ 0.05) in leaf followed by fruit and flower and Mg, Fe, and Zn contents were significantly higher (P ≤ 0.05) in leaves followed by flowers and fruits. In conclusion, T. cucumerina can be considered as a nourishing food commodity which possesses high nutritional and functional benefits for human health.

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

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

Rice (Oryza sativa japonica) Albumin Suppresses the Elevation of Blood Glucose and Plasma Insulin Levels after Oral Glucose Loading

The suppressive effect of rice albumin (RA) of 16 kDa on elevation of blood glucose level after oral loading of starch or glucose and its possible mechanism were examined. RA suppressed the increase in blood glucose levels in both the oral starch tolerance test and the oral glucose tolerance test. The blood glucose concentrations 15 min after the oral administration of starch were 144 ± 6 mg/dL for control group and 127 ± 4 mg/dL for RA 200 mg/kg BW group, while those after the oral administration of glucose were 157 ± 7 mg/dL for control group and 137 ± 4 mg/dL for RA 200 mg/kg BW group. However, in the intraperitoneal glucose tolerance test, no significant differences in blood glucose level were observed between RA and the control groups, indicating that RA suppresses the glucose absorption from the small intestine. However, RA did not inhibit the activity of mammalian α-amylase. RA was hydrolyzed to an indigestible high-molecular-weight peptide (HMP) of 14 kDa and low-molecular-weight peptides by pepsin and pancreatin. Furthermore, RA suppressed the glucose diffusion rate through a semipermeable membrane like dietary fibers in vitro. Therefore, the indigestible HMP may adsorb glucose and suppress its absorption from the small intestine.

The role of alginates in regulation of food intake and glycemia: a gastroenterological perspective

Regulation of food intake through modulation of gastrointestinal responses to ingested foods is an ever-growing component of the therapeutic approaches targeting the obesity epidemic. Alginates, viscous and gel-forming soluble fibers isolated from the cell wall of brown seaweeds and some bacteria, are recently receiving considerable attention because of their potential role in satiation, satiety, and food intake regulation in the short term. Enhancement of gastric distension, delay of gastric emptying, and attenuation of postprandial glucose responses may constitute the basis of their physiological benefits. Offering physical, chemical, sensorial, and physiological advantages over other viscous and gel-forming fibers, alginates constitute promising functional food ingredients for the food industry. Therefore, the current review explores the role of alginates in food intake and glycemic regulation, their underlying modes of action and their potential in food applications.

High Molecular Weight Barley β-Glucan Alters Gut Microbiota Toward Reduced Cardiovascular Disease Risk

The physiological cholesterol-lowering benefits of β-glucan have been well documented, however, whether modulation of gut microbiota by β-glucan is associated with these physiological effects remains unknown. The objectives of this study were therefore to determine the impact of β-glucan on the composition of gut microbiota in mildly hypercholesterolemic individuals and to identify if the altered microbiota are associated with bioactivity of β-glucan in improving risk factors of cardiovascular disease (CVD). Using a randomized, controlled crossover study design, individuals received for 5-week either a treatment breakfast containing 3 g high molecular weight (HMW), 3 g low molecular weight (LMW), 5 g LMW barley β-glucan, or wheat and rice. The American Heart Association (AHA) diet served as the background diet for all treatment groups. Phases were separated by 4-week washout periods. Fecal samples were collected at the end of each intervention phase and subjected to Illumina sequencing of 16S rRNA genes. Results revealed that at the phylum level, supplementation of 3 g/d HMW β-glucan increased Bacteroidetes and decreased Firmicutes abundances compared to control (P < 0.001). At the genus level, consumption of 3 g/d HMW β-glucan increased Bacteroides (P < 0.003), tended to increase Prevotella (P < 0.1) but decreased Dorea (P < 0.1), whereas diets containing 5 g LMW β-glucan and 3 g LMW β-glucan failed to alter the gut microbiota composition. Bacteroides, Prevotella, and Dorea composition correlated (P < 0.05) with shifts of CVD risk factors, including body mass index, waist circumference, blood pressure, as well as triglyceride levels. Our data suggest that consumption of HMW β-glucan favorably alters the composition of gut microbiota and this altered microbiota profile associates with a reduction of CVD risk markers. Together, our study suggests that β-glucan induced shifts in gut microbiota in a MW-dependent manner and that might be one of the underlying mechanisms responsible for the physiological benefits of β-glucan.

An oat bran-based beverage reduce postprandial glycaemia equivalent to yoghurt in healthy overweight subjects

An acute meal study was performed to determine postprandial glucose and insulin responses after consumption of two fermented oat bran-based beverages (with and without exopolysaccharides) and yoghurt. This randomized, single-blind, within-subject study included 18 healthy, overweight participants. Four breakfast meals, including a reference meal, were tested; all meals contained 50 g of available carbohydrates, but differed in energy and macronutrient composition. All experimental meals reduced the postprandial glucose response compared with the reference meal. The oat drinks as well as the yoghurt elicited higher early (0-15 min) insulin responses, but the overall insulinaemia were similar to the reference meal. A new food product containing fermented liquid oat bran and milk reduced the postprandial blood glucose response as efficiently as yoghurt after a high-glycaemic index white wheat bread meal, but the presence of microbial exopolysaccharides did not affect the outcome.

A double-blind randomised controlled trial testing the effect of a barley product containing varying amounts and types of fibre on the postprandial glucose response of healthy volunteers

The aim of the present study was to determine if the consumption of barley tortillas varying in fibre and/or starch composition affected postprandial glucose, insulin, glucagon-like peptide-1 (GLP-1) or peptide YY concentrations. A double-blind, randomised, controlled trial was performed with twelve healthy adults. They each consumed one of five barley tortillas or a glucose drink on six individual visits separated by at least 1 week. Tortillas were made from 100% barley flour blends using five different milling fractions to achieve the desired compositions. All treatments provided 50 g of available carbohydrate and were designed to make the following comparisons: (1) low-starch amylose (0%) v. high-starch amylose (42%) with similar β-glucan and insoluble fibre content; (2) low β-glucan (4.5 g) v. medium β-glucan (7.8 g) v. high β-glucan (11.6 g) with similar starch amylose and insoluble fibre content; and (3) low insoluble fibre (7.4 g) v. high insoluble fibre (19.6 g) with similar starch amylose and β-glucan content. Blood was collected at fasting and at multiple intervals until 180 min after the first bite/sip of the test product. Amylose and insoluble fibre content did not alter postprandial glucose and insulin, but high-β-glucan tortillas elicited a lower glucose and insulin response as compared to the low-β-glucan tortillas. The tortillas with high insoluble fibre had a higher AUC for GLP-1 as compared to the tortillas with low insoluble fibre, whereas amylose and β-glucan content had no effect. Results show that processing methods can be used to optimise barley foods to reduce postprandial blood glucose responses and factors that may influence satiety.

Whole grain oats improve insulin sensitivity and plasma cholesterol profile and modify gut microbiota composition in C57BL/6J mice

BACKGROUND

Whole grain consumption reduces the risk of major chronic diseases. It is not clear how whole grains exert their beneficial effects.

OBJECTIVE

The aim was to compare the physiologic effects of whole grain oat (WGO) flour with low bran oat (LBO) flour.

METHODS

Two AIN-93G-based diets were formulated with either WGO or LBO flour. Five-week-old male C57BL/6J mice were fed LBO (n = 11) and WGO (n = 13) diets for 8 wk. Cecal microbiota was profiled by pyrosequencing of the 16S ribosomal RNA gene. Data are reported as means ± SEMs or antilogs of the mean (mean - SEM, mean + SEM).

RESULTS

The weight gain was 14.6% less in the WGO group during week 7 (P = 0.04). WGO improved insulin sensitivity as reflected by significantly lower plasma insulin [1500 (1370, 1650) ng/L vs. 2340 (2090, 2620) ng/L; P = 0.006], C-peptide (3980 ± 548 ng/L vs. 7340 ± 1050 ng/L; P = 0.007), and homeostasis model assessment-estimated insulin resistance (21.4 ± 2.3 vs. 34.7 ± 4.9; P = 0.03). Plasma total cholesterol was 9.9% less and non-HDL cholesterol was 11% less in the WGO group. A comparison of relative abundance indicated Prevotellaceae, Lactobacillaceae, and Alcaligenaceae families were 175.5% (P = 0.03), 184.5% (P = 0.01), and 150.0% (P = 0.004), respectively, greater in the WGO group and Clostridiaceae and Lachnospiraceae families were 527% (P = 0.004) and 62.6% (P = 0.01), respectively, greater in the LBO group. Cecal microbiota composition predicts 63.9% variation in plasma insulin and 88.9% variation in plasma non-HDL cholesterol.

CONCLUSIONS

In mice, WGOs improved insulin sensitivity and plasma cholesterol profile compared with LBOs, and the effects were associated with the changes in cecal microbiota composition. Increasing WGO consumption may help improve insulin sensitivity and dyslipidemia in chronic diseases.

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.

Overview of food products and dietary constituents with antidiabetic properties and their putative mechanisms of action: a natural approach to complement pharmacotherapy in the management of diabetes

Diabetes is one of the fastest growing chronic, noncommunicable diseases worldwide. Currently, 11 major classes of pharmacotherapy are available for the management of this metabolic disorder. However, the usage of these drugs is often associated with undesirable side effects, including weight gain and hypoglycemia. There is thus a need for new, safe and effective treatment strategies. Diet is known to play a major role in the prevention and management of diabetes. Numerous studies have reported the putative association of the consumption of specific food products, or their constituents, with the incidence of diabetes, and mounting evidence now suggests that some dietary factors can improve glycemic regulation. Foods and dietary constituents, similar to synthetic drugs, have been shown to modulate hormones, enzymes, and organ systems involved in carbohydrate metabolism. The present article reviews the major classes and modes of action of antidiabetic drugs, and examines the evidence on food products and dietary factors with antidiabetic properties as well as their plausible mechanisms of action. The findings suggest potential use of dietary constituents as a complementary approach to pharmacotherapy in the prevention and/or management of diabetes, but further research is necessary to identify the active components and evaluate their efficacy and safety.

Effects of juices enriched with xanthan and β-glucan on the glycemic response and satiety of healthy men

This study compared the effects of 3 palatable juices enriched with different polysaccharides with a control nonenriched juice on glucose and insulin responses as well as on appetite sensations and determined whether the polysaccharide-induced viscosity contributed to the effects of enriched juices on these variables. Using a randomized crossover design, 14 healthy male subjects consumed 4 juices: 3 juices were enriched with either xanthan gum, β-glucan, or a mix of xanthan gum and β-glucan, and the control juice had no added polysaccharides. Viscosity was measured at a shear rate of 30 s−1, which represented an approximation of the viscosity in the gastrointestinal tract. One-sided tests were used in this study. Compared with the control juice, the juice supplemented with the mix of xanthan gum and β-glucan and the juice enriched with β-glucan alone led to a significant attenuation of the incremental peak of glucose (–0.8 mmol·L−1, p = 0.001; and –0.5 mmol·L−1, p = 0.03; respectively). However, no difference between juices was found for the incremental area under the curve for glucose, insulin, and appetite sensations. At 30 s−1, only juices enriched with either the β-glucan/xanthan mixture or β-glucan alone yielded viscosity values higher than 0.1 Pa·s. These results highlight that the consumption of a palatable juice enriched with β-glucan alone or in mixture with xanthan gum reduces the glucose peak response compared with a juice with no added polysaccharides. The viscosity at a shear rate of 30 s−1 seems to be linked to this effect.

Review of human studies investigating the post-prandial blood-glucose lowering ability of oat and barley food products

Oat and barley foods have been shown to reduce human glycaemic response, compared to similar wheat foods or a glucose control. The strength of the evidence supporting the hypothesis that the soluble fibre, mixed linkage β-glucan, reduces glycaemic response was evaluated. A search of the literature was conducted to find clinical trials with acute glycaemic response as an end point using oat or barley products. Of the 76 human studies identified, 34 met the inclusion and exclusion criteria. Dose response and ratio of β-glucan to available carbohydrate as predictors of glycaemic response were assessed. Meals provided 0.3-12.1 g oat or barley β-glucan, and reduced glycaemic response by an average of 48 ± 33 mmol · min/l compared to a suitable control. Regression analysis on 119 treatments indicated that change in glycaemic response (expressed as incremental area under the post-prandial blood-glucose curve) was greater for intact grains than for processed foods. For processed foods, glycaemic response was more strongly related to the β-glucan dose alone (r(2)=0.48, P<0.0001) than to the ratio of β-glucan to the available carbohydrate (r(2)=0.25, P<0.0001). For processed foods containing 4 g of β-glucan, the linear model predicted a decrease in glycaemic response of 27 ± 3 mmol · min/l, and 76% of treatments significantly reduced glycaemic response. Thus, intact grains as well as a variety of processed oat and barley foods containing at least 4 g of β-glucan and 30-80 g available carbohydrate can significantly reduce post-prandial blood glucose.

Impact of a resistant dextrin with a prolonged oxidation pattern on day-long ghrelin profile

OBJECTIVES

The effects of a new resistant dextrin ingested at breakfast on day-long metabolic parameters and ghrelin profile at subsequent lunch were investigated.

METHODS

In this randomized, single-blinded, crossover study, 12 healthy men ingested a standardized breakfast with 50 g of NUTRIOSE 10, a resistant dextrin (RD), or of maltodextrin (Malto) and a standardized lunch 5 hours later. Both products (RD and Malto) were derived from corn naturally rich in (13)C to follow their metabolic fate (by using stable isotope analysis). Oxidation and fermentation patterns were assessed by simultaneous (13)CO(2)/H(2) breath testing. The appearance of exogenous (13)C-glucose in plasma, glycemia, insulinemia, nonesterified fatty acids (NEFAs), and ghrelin concentrations were measured for 10 hours following breakfast ingestion.

RESULTS

With RD, H(2) excretion (fermentation) was significantly enhanced compared with Malto, whereas the appearance of (13)CO(2) (oxidation) was significantly prolonged (p < 0.0001). Following breakfast, ghrelin secretion was significantly less inhibited and NEFA concentration was higher with RD (p < 0.05), but unexpectedly, both remained lower after lunch and up to T600 minutes. According to the reduced bioavailability of RD compared with Malto, the appearance of (13)C-glucose in plasma (p < 0.0001) and glycemic and insulinemic responses to breakfast (p < 0.05) were significantly reduced.

CONCLUSIONS

Ingestion of this new resistant dextrin at breakfast decreased ghrelin concentrations in response to the subsequent lunch, even if the caloric load ingested at breakfast was lower. This effect may be linked to the prolonged fermentation/oxidation pattern seen in the late postprandial phase (up to 10 hours after ingestion at breakfast), and thus prolonged energy release with the resistant dextrin.

Beta glucan: health benefits in obesity and metabolic syndrome

Despite the lack of international agreement regarding the definition and classification of fiber, there is established evidence on the role of dietary fibers in obesity and metabolic syndrome. Beta glucan (β-glucan) is a soluble fiber readily available from oat and barley grains that has been gaining interest due to its multiple functional and bioactive properties. Its beneficial role in insulin resistance, dyslipidemia, hypertension, and obesity is being continuously documented. The fermentability of β-glucans and their ability to form highly viscous solutions in the human gut may constitute the basis of their health benefits. Consequently, the applicability of β-glucan as a food ingredient is being widely considered with the dual purposes of increasing the fiber content of food products and enhancing their health properties. Therefore, this paper explores the role of β-glucans in the prevention and treatment of characteristics of the metabolic syndrome, their underlying mechanisms of action, and their potential in food applications.

Lupin and soya reduce glycaemia acutely in type 2 diabetes

Addition of fibre or protein to carbohydrate-rich foods can reduce the glycaemic response to those foods. This may assist with glycaemic management in individuals with type 2 diabetes. Lupin is a legume rich in fibre and protein. We assessed the acute effects of lupin- and soya-based beverages on glucose and insulin responses in type 2 diabetic individuals. We hypothesised that the lupin and soya beverages would lower the acute glycaemic response compared with a control beverage containing no protein or fibre, and that lupin would reduce the postprandial glucose more than soya. In a randomised, controlled, cross-over trial, twenty-four diabetic adults (nineteen men and five women) attended three testing sessions, each 1 week apart. At each session, participants consumed a beverage containing 50 g glucose (control), 50 g glucose plus lupin kernel flour with 12·5 g fibre and 22 g protein (lupin), or 50 g glucose plus 12·5 g fibre and 22 g protein from soya isolates (soya). Serum glucose, insulin and C-peptide were measured periodically for 4 h following beverage consumption. Compared with the control beverage, the 4 h post-beverage glucose response was lower (P < 0·001), and the 4 h post-beverage insulin and C-peptide responses were higher (P < 0·001) for lupin and soya. Glucose (P = 0·25) and C-peptide (P = 0·07) responses did not differ significantly between lupin and soya, but lupin resulted in a lower insulin response compared with soya (P = 0·013). Adding lupin or soya to a carbohydrate-rich beverage reduces glycaemia acutely in type 2 diabetic individuals. This may have a beneficial role in glycaemic management.

Development of shelf stable protein rich composite cereal bar

Protein rich composite cereal bar based on cereal ingredients was prepared using semi automatic tablet making machine, packed in poly propylene (PP), paper aluminium foil polyethylene (PFP), metallised polyester (MP) followed by vacuum packing in metallized polyester films. Proximate composition, mineral contents as well as changes in peroxide value (PV), free fatty acid value (FFA), thiobarbituric acid value (TBA), browning, fatty acid profile, vitamins, effect of water activity on lipid peroxidation, fortification with vitamins and minerals, microbiological as well as sensory parameters during storage under ambient (15-34°C) and 37°C temperature conditions were studied. Composite cereal bar remained shelf stable for 3 months in PP and 6 months in PFP, MP and MP plus vacuum packing under ambient and 37°C temperature conditions.

[Dietary fibers: current trends and health benefits in the metabolic syndrome and type 2 diabetes]

Dietary fiber may contribute to both the prevention and treatment of type 2 diabetes mellitus (T2DM). In epidemiological studies the intake of insoluble fiber, but not the intake of soluble fiber, has been inversely associated with the incidence of T2DM. In contrast, in postprandial studies, meals containing sufficiently quantities of beta-glucan, psyllium, or guar gum have decreased insulin and glucose responses in both healthy individuals and patients with T2DM. Diets enriched sufficiently in soluble fiber may also improve overall glycemic control in T2DM. Insoluble fiber has little effect on postprandial insulin and glucose responses. Fiber increases satiety. In some studies, insoluble fiber has been associated with less weight gain over time. Limited cross-sectional evidence suggests an inverse relationship between intake of cereal fiber and whole-grains and the prevalence of the metabolic syndrome. Although long-term data from trials focusing on specifically dietary fiber are lacking, meeting current recommendations for a minimum fiber intake of 25 g/d based on a diet rich in whole grains, fruits and legumes will probably decrease the risk of obesity, the metabolic syndrome and T2DM.

Effect of adding the novel fiber, PGX®, to commonly consumed foods on glycemic response, glycemic index and GRIP: a simple and effective strategy for reducing post prandial blood glucose levels--a randomized, controlled trial

BACKGROUND

Reductions in postprandial glycemia have been demonstrated previously with the addition of the novel viscous polysaccharide (NVP), PolyGlycopleX® (PGX®), to an OGTT or white bread. This study explores whether these reductions are sustained when NVP is added to a range of commonly consumed foods or incorporated into a breakfast cereal.

METHODS

Ten healthy subjects (4M, 6F; age 37.3 ± 3.6 y; BMI 23.8 ± 1.3 kg/m2), participated in an acute, randomized controlled trial. The glycemic response to cornflakes, rice, yogurt, and a frozen dinner with and without 5 g of NVP sprinkled onto the food was determined. In addition, 3 granolas with different levels of NVP and 3 control white breads and one white bread and milk were also consumed. All meals contained 50 g of available carbohydrate. Capillary blood samples were taken fasting and at 15, 30, 45, 60, 90 and 120 min after the start of the meal. The glycemic index (GI) and the glycemic reduction index potential (GRIP) were calculated. The blood glucose concentrations at each time and the iAUC values were subjected to repeated-measures analysis of variance (ANOVA) examining for the effect of test meal. After demonstration of significant heterogeneity, differences between individual means was assessed using GLM ANOVA with Tukey test to adjust for multiple comparisons.

RESULTS

Addition of NVP reduced blood glucose response irrespective of food or dose (p < 0.01). The GI of cornflakes, cornflakes+NVP, rice, rice+NVP, yogurt, yogurt+NVP, turkey dinner, and turkey dinner+NVP were 83 ± 8, 58 ± 7, 82 ± 8, 45 ± 4, 44 ± 4, 38 ± 3, 55 ± 5 and 41 ± 4, respectively. The GI of the control granola, and granolas with 2.5 and 5 g of NVP were 64 ± 6, 33 ± 5, and 22 ± 3 respectively. GRIP was 6.8 ± 0.9 units per/g of NVP.

CONCLUSION

Sprinkling or incorporation of NVP into a variety of different foods is highly effective in reducing postprandial glycemia and lowering the GI of a food.

CLINICAL TRIAL REGISTRATION

NCT00935350.

Reduction of postprandial glycemia by the novel viscous polysaccharide PGX, in a dose-dependent manner, independent of food form

OBJECTIVE

Health benefits of viscous fiber intake are well established; nevertheless few effective and palatable preparations are available. The objective of the study therefore was to determine palatability and effectiveness of escalating doses of PGX, a novel viscous polysaccharide (NVP), in reducing postprandial glycemia when added to a liquid and a solid meal.

DESIGN

Two open-label, randomized, controlled trials were undertaken.

SETTING

Glycemic Index Laboratories, Inc, Toronto, Ontario, Canada.

SUBJECTS

Two groups of 10 healthy subjects each (group 1: 5 M, 5 F; 35.6 +/- 13.2 y; 24.6 +/- 2.1 kg/m(2); and group 2: 3 M, 7 F; 33.5 +/- 11.1 y; 26.3 +/- 5.2 kg/m(2)) were studied.

INTERVENTIONS

Zero, 2.5, 5, and 7.5 g of NVP were added to a glucose drink (group 1) or to white bread and margarine (WB + Marg) (group 2). Subjects repeated glucose control (group 1) or WB control (group 2) 3 times to allow calculation of the glycemic index (GI). Measures of Outcomes: Palatability of foods and capillary blood glucose concentrations were measured fasting and at 15, 30, 45, 60, 90, and 120 minutes after the start of the meal.

RESULTS

Addition of NVP to the meal reduced blood glucose incremental areas under the curve irrespective of dose, reaching significance at the 7.5 g dose when added to glucose (p < 0.01), and at the 5 and 7.5 g doses when added to WB + Marg (p < 0.001). The GI values of glucose with 0, 2.5, 5, or 7.5 g of NVP were (mean +/- standard error of the mean [SEM]) 100.0 +/- 0.0, 83.7 +/- 9.0, 77.7 +/- 8.2, and 72.5 +/- 5.9, respectively; the GI of the WB alone, or of WB + Marg, with 0, 2.5, 5, or 7.5 g of NVP was 71.0 +/- 0.0, 66.8 +/- 3.0, 47.5 +/- 5.9, 37.3 +/- 5.9, and 33.9 +/- 3.6, respectively.

CONCLUSION

Addition of NVP to different food matrices is highly effective in lowering the glycemic index of a food in a dose-responsive manner.

New hypotheses for the health-protective mechanisms of whole-grain cereals: what is beyond fibre?

Epidemiological studies have clearly shown that whole-grain cereals can protect against obesity, diabetes, CVD and cancers. The specific effects of food structure (increased satiety, reduced transit time and glycaemic response), fibre (improved faecal bulking and satiety, viscosity and SCFA production, and/or reduced glycaemic response) and Mg (better glycaemic homeostasis through increased insulin secretion), together with the antioxidant and anti-carcinogenic properties of numerous bioactive compounds, especially those in the bran and germ (minerals, trace elements, vitamins, carotenoids, polyphenols and alkylresorcinols), are today well-recognised mechanisms in this protection. Recent findings, the exhaustive listing of bioactive compounds found in whole-grain wheat, their content in whole-grain, bran and germ fractions and their estimated bioavailability, have led to new hypotheses. The involvement of polyphenols in cell signalling and gene regulation, and of sulfur compounds, lignin and phytic acid should be considered in antioxidant protection. Whole-grain wheat is also a rich source of methyl donors and lipotropes (methionine, betaine, choline, inositol and folates) that may be involved in cardiovascular and/or hepatic protection, lipid metabolism and DNA methylation. Potential protective effects of bound phenolic acids within the colon, of the B-complex vitamins on the nervous system and mental health, of oligosaccharides as prebiotics, of compounds associated with skeleton health, and of other compounds such as alpha-linolenic acid, policosanol, melatonin, phytosterols and para-aminobenzoic acid also deserve to be studied in more depth. Finally, benefits of nutrigenomics to study complex physiological effects of the 'whole-grain package', and the most promising ways for improving the nutritional quality of cereal products are discussed.