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

Gas chromatography/mass spectrometry-based metabolite profiling of chia and quinoa seeds in comparison with wheat and oat

INTRODUCTION

With an increasing interest in healthy and affordable cereal intake, efforts are made toward exploiting underutilized cereals with high nutritional values.

OBJECTIVES

The current study aims to explore the metabolome diversity in 14 cultivars of chia and quinoa collected from Germany, Austria, and Egypt, compared with wheat and oat as major cereals.

MATERIAL AND METHODS

The samples were analyzed using gas chromatography-mass spectrometry (GC-MS). Multivariate data analysis (MVA) was employed for sample classification and markers characterization.

RESULTS

A total of 114 metabolites were quantified (sugars, alcohols, organic and amino acids/nitrogenous compounds, fatty acids/esters), but the inorganic and phenolic acids were only identified. Fatty acids were the major class followed by amino acids in quinoa and chia. Chia and oats were richer in sucrose. Quinoa encompassed higher amino acids. Quinoa and chia were rich in essential amino acids. Higher levels of unsaturated fatty acids especially omega 6 and omega 9 were detected in quinoa versus omega 3 in chia compared with oat and wheat, whereas ω6/ω3 fatty acid ratio of chia was the lowest. To the best of our knowledge, this is the first comprehensive metabolite profiling of these pseudo cereals.

CONCLUSION

Quinoa and chia, especially red chia, are more nutritionally valuable compared with oat and wheat because of their compositional profile of free amino acids, organic acids, and essential fatty acids, besides their low ω6/ω3 fatty acid ratio. Such results pose them as inexpensive alternative to animal proteins and encourage their inclusion in infant formulas.

The acute effect of a β-glucan-enriched oat bread on gastric emptying, GLP-1 response, and postprandial glycaemia and insulinemia: a randomised crossover trial in healthy adults

BACKGROUND

The cereal fibre β-glucan reduces postprandial glycaemia, however, the underlying mechanisms are not fully understood. Thus, the aim of this study was to investigate the acute effect of a β-glucan-enriched oat bread on gastric emptying half-time (T1/2), gastric emptying lag phase (Tlag), and gastric emptying rate (GER), and the secretion of glucagon-like peptide-1 (GLP-1) as potential means to influence postprandial glycaemia.

METHODS

A randomised crossover trial was conducted in 22 healthy adults (age 24.6 ± 3.1 years, BMI 23.1 ± 2.7 kg/m2) receiving 25 g available carbohydrates from a β-glucan-enriched oat bread or a control whole-wheat bread at two non-consecutive days. T1/2, Tlag, and GER were determined based on ultrasound measures of the cross-sectional gastric antrum area in the fasting state and 15, 30, 45, 60, 90, and 120 min postprandially. Capillary glucose, serum insulin, and plasma GLP-1 concentrations were measured at the same time points.

RESULTS

A biphasic pattern of gastric emptying with a distinct Tlag before the commencement of emptying was observed in most subjects for both bread types. While no differences in GER were evident (p = 0.562), consumption of the oat bread significantly increased T1/2 by 18 min and Tlag by 14 min compared with the whole-wheat bread (p = 0.005 and p = 0.010, respectively). In addition, the oat bread significantly reduced iAUC2h for glucose and insulin responses compared with the whole-wheat bread (p = 0.001 and p < 0.001, respectively). There were no significant differences in GLP-1 response between the two breads (p = 0.892).

CONCLUSION

The increased T1/2 and Tlag could offer a potential mechanism for the observed attenuation of postprandial glycaemia and insulinemia after consumption of the β-glucan-enriched oat bread compared with the whole-wheat bread.

TRIAL REGISTRATION

 The study is registered at clinicaltrails.gov (NCT04571866).

Greater adherence to the Healthy Nordic Food Index is associated with lower all-cause mortality in a population-based sample from northern Germany

PURPOSE

Dietary pattern scores reflecting a high intake of beneficial food groups were associated with reduced mortality risk. Data on associations of such dietary pattern scores in population-based samples from northern Germany are lacking. Therefore, we examined the association of three dietary pattern scores with all-cause mortality in a moderate-sized prospective sample from northern Germany.

METHODS

The study sample comprised 836 participants (43.8% females, median age 62.4 years). Based on a validated, self-administered Food Frequency Questionnaire, the dietary scores Dietary Approaches to Stop Hypertension (DASH), Modified Mediterranean Diet Score (MMDS), and Healthy Nordic Food Index (HNFI) were calculated. Cox proportional hazard regression models, adjusted for age, sex, body mass index, waist to hip ratio, education, smoking status, total energy intake, and physical activity, were used to separately relate DASH, MMDS, and HNFI to all-cause mortality.

RESULTS

During a median follow-up period of 11 years, 93 individuals died. While DASH and MMDS scores were not associated with all-cause mortality, greater adherence to HNFI was associated with lower mortality hazards (HR: 0.47 [95% CI 0.25-0.89] when comparing the highest score quartile to the lowest; HR: 0.79 [95% CI 0.64-0.98] for HNFI modeled as a 1-Standard Deviation increment). Among different HNFI components, higher intake of oats and cereals displayed the most conclusive association with all-cause mortality (HR: 0.59 [95% CI 0.38-0.91] when comparing high and low intake).

CONCLUSION

In an elderly general population sample from northern Germany, we observed greater adherence to HNFI to be associated with lower all-cause mortality.

Beneficial glycaemic effects of high-amylose barley bread compared to wheat bread in type 2 diabetes

BACKGROUND

Cereals foods with a high content of dietary fibres or amylose have potential to lower postprandial glucose levels. Optimisation of cereal foods may improve management of type 2 diabetes (T2D).

METHODS

We investigated the impact on 4 h postprandial glucose responses given as incremental area under curve (iAUC) of bread made of either 50% RNAi-based (genetically modified) amylose-only barley flour (AmOn) (and 50% wheat flour), 50% hulless barley flour (and 50% wheat flour) or 75% hulless barley (and 25% wheat flour) in subjects with T2D compared with 100% wheat flour bread.

DESIGN

Twenty adults with T2D were randomly allocated to one of four breads at four separate visits. We measured fasting and 4 h postprandial responses of glucose, insulin, glucagon, triacylglycerol (TG), free fatty acids (FFA), glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP). Mixed model ANOVA was used to examine the differences.

RESULTS

Bread made from 50% AmOn lowered the 4 h postprandial glucose by 34%, 27%, 23% (P < 0.05) compared with 100% wheat, 50% or 75% hulless barley, respectively. Bread made from 75% hulless barley reduced the postprandial glucose response (iAUC) by 11% (P < 0.05) compared to 100% wheat bread. Postprandial insulin responses (iAUC) were reduced for 50% AmOn compared with 100% wheat and 50% hulless barley and for 75% hulless compared to 50% hulless barley bread (P < 0.05). 4 h postprandial glucagon (tAUC) did not differ between the four bread types (P > 0.05). Lower postprandial GIP (iAUC) was observed after all barley breads compared to 100% wheat (P < 0.05), whereas no difference was seen in postprandial GLP-1. Postprandial TG and FFA (tAUC) were difficult to judge due to differences in fasting values.

CONCLUSIONS

Bread made by replacing wheat flour with either 50% high-amylose or 75% hulless barley flour lowered postprandial glucose responses compared to 100% wheat bread indicating a beneficial impact on glucose regulation in T2D subjects. This trial was registered at clinicaltrials.gov as NCT04646746.

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.

Dietary Fibers in Healthy Children and in Pediatric Gastrointestinal Disorders: A Practical Guide

Dietary fibers include non-digestible plant carbohydrates, lignin and resistant starch. Dietary fibers provide immune, cardiovascular, metabolic and intestinal beneficial effects in humans. Fibers naturally present in foods (fruits, vegetables, legumes, cereals) or used as supplements have different physical, chemical and functional profiles. This narrative review provides an update to the knowledge on the effects of dietary fibers in healthy subjects and in children with gastrointestinal disorders. Soluble fibers are digested by gut bacteria, producing short-chain fatty acids and energy for colonocytes, and may exert prebiotic effects that promote the growth of bifidobacteria and lactobacilli. Non-soluble fibers are bulking agents and may improve intestinal transit. The exact amount and characteristics of the fiber requirement in infants and children need to be further established. There are limited data evaluating fibers in children with gastrointestinal disorders. The low intake of fibers has been associated with constipation, but the intake of excessive fibers is not recommended as it may cause flatulence and abdominal discomfort. Certain fibers (particularly psyllium in irritable bowel syndrome) have shown beneficial effects in children with gastrointestinal disorders, but the limited and heterogenous data do not currently allow a specific recommendation.

Plant compounds for obesity treatment through neuroendocrine regulation of hunger: A systematic review

BACKGROUND

Food intake behavior is influenced by both physiological and psychological complex processes, such as appetite, satiety, and hunger. The neuroendocrine regulation of food intake integrates short- and long-term acting signals that modulate the moment of intake and energy storage/expenditure, respectively. These signals are classified as orexigenic, those that activate anabolic pathways and the desire of eating, and anorexigenic, those that activate the catabolic pathways and a sensation of satiety. Appetite control by natural vegetal compounds is an intense area of research and new pharmacological interventions have been emerging based on an understanding of appetite regulation pathways. Several validated psychometric tools are used to assess the efficacy of these plant ingredients. However, these data are not conclusive if they are not complemented with physiological parameters, such as anthropometric evaluations (body weight and composition) and the analysis of hormones related to adipose tissue and appetite in blood.

PURPOSE

The purpose of this manuscript is the critical analysis of the plant compounds studied to date in the literature with potential for the neuroendocrine regulation of hunger in order to determine if the use of phytochemicals for the treatment of obesity constitutes an effective and/or promising therapeutic tool.

METHODS

Relevant information on neuroendocrine regulation of hunger and satiety for the treatment of obesity by plant compounds up to 2022 in English and/or Spanish were derived from online databases using the PubMed search engine and Google Scholar with relevant keywords and operators.

RESULTS

Accordingly, the comparison performed in this review between previous studies showed a high degree of experimental heterogeneity. Among the studies reviewed here, only a few of them establish comprehensively a potential correlation between the effect of the ingredient on hunger or satiety, body changes and a physiological response.

CONCLUSIONS

More systematic clinical studies are required in future research. The first approach should be to decode the pattern of circulating hormones regulating hunger, satiety, and appetite in overweight/obese subjects. Thereafter, studies should correlate brain connectivity at the level of the hypothalamus, gut and adipose tissue with the hormone patterns modulating appetite and satiety. Extracts whose mode of action have been well characterized and that are safe, can be used clinically to perform a moderate, but continuous, caloric restriction in overweight patients to lose weight excess into a controlled protocol.

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.

Effect of a regular consumption of traditional and roasted oat and barley flakes on blood lipids and glucose metabolism-A randomized crossover trial

Background

Regular consumption of the soluble dietary fiber β-glucan is associated with decreased total cholesterol (TC), low-density lipoprotein (LDL) cholesterol and blood glucose. Barley and oat flakes as natural sources of β-glucan were roasted to improve sensory quality. The aim of this study was to investigate whether roasting of barley and oat flakes changes the physiological impact of the β-glucan-rich flakes on glucose and lipid metabolism.

Method

A five-armed randomized crossover trial design was used. The intervention study was conducted from May 2018 to May 2019 and included 32 healthy subjects with moderately increased LDL cholesterol (≥2.5 mmol/L). During the 3-week intervention periods, 80 g of roasted or traditional barley or oat flakes, or four slices of white toast bread per day were consumed for breakfast. At the start and the end of each intervention, fasting and postprandial blood was taken. The intervention periods were separated by 3-week wash-out periods.

Results

During the interventions with the cereal flakes, TC and LDL cholesterol concentrations were significantly reduced compared to baseline values by mean differences of 0.27-0.33 mmol/L and 0.21-0.30 mmol/L, respectively (p < 0.05), while high-density lipoprotein (HDL) cholesterol was only reduced after the intervention with barley flakes (p < 0.05). After the intervention period with toast, TC and HDL cholesterol increased (p < 0.05). The fasting levels of triglycerides, fasting blood glucose and insulin did not change in any group. The effects of traditional and roasted varieties on blood lipids did not differ between the groups.

Conclusion

The regular consumption of traditional or roasted barley and oat flakes contributes to the management of cardiovascular diseases by improving TC and LDL cholesterol.

Clinical trial registration

https://clinicaltrials.gov/ct2/show/NCT03648112, identifier NCT03648112.

Potential Role of ROS in Butyrate- and Dietary Fiber-Mediated Growth Inhibition and Modulation of Cell Cycle-, Apoptosis- and Antioxidant-Relevant Proteins in LT97 Colon Adenoma and HT29 Colon Carcinoma Cells

The aim of the present study was to examine whether reactive oxygen species (ROS) contribute to chemopreventive effects of fermentation supernatants (FS) of different dietary fibers (Synergy1^®, oat-, barley-, yeast β-glucan, Curdlan) and butyrate as a fermentation metabolite. LT97 and HT29 cells were treated with butyrate and FS alone or with N-acetyl-cysteine (NAC) and their impact on ROS formation, cell growth, and protein expression (Cyclin D2, p21, PARP, Bid, GPx2) was investigated. Butyrate and FS significantly decreased cell growth. ROS levels were significantly increased, particularly in LT97 cells, while co-treatment with NAC decreased ROS formation and growth inhibitory effects in both cell lines. After treatment with butyrate and FS, Cyclin D2 expression was reduced in LT97 cells and p21 expression was increased in both cell lines. Levels of full-length PARP and Bid were decreased, while levels of cleaved PARP were enhanced. GPx2 expression was significantly reduced by fiber FS in HT29 cells. A notable effect of NAC on butyrate- and FS-modulated protein expression was observed exclusively for PARP and Bid in HT29 cells. From the present results, a contribution of ROS to growth inhibitory and apoptotic effects of butyrate and FS on LT97 and HT29 cells cannot be excluded.

Acute effect of Melon Manis Terengganu peel powder on glycemic response, perceived satiety, and food intake: a randomized, placebo-controlled crossover trial in adults at risk of type 2 diabetes

BACKGROUND

Melon Manis Terengganu (MMT) peel has a high dietary fiber content, but there is no data examining its health benefits in adults at risk of type 2 diabetes. The objective of the study was to evaluate whether consumption of MMT peel powder improves glycemic response, satiety, and food intake in adults at risk of type 2 diabetes.

METHODS

An open-label, randomized, placebo-controlled, crossover design trial was conducted among adults (n = 30, ages 18-59 y) at risk of type 2 diabetes. They consumed Formulation 3 (formulated MMT peel powder) [A] and control (glucose) [B] with study breakfast based on randomly assigned treatment sequences (AB, BA) established by Research Randomizer ( www.randomizer.org ). Capillary blood glucose and perceived satiety were determined at baseline (0 min), 30, 60, 90 and 120 min, followed by a post-intervention food intake measurement.

RESULTS

The repeated measures analysis of variance (ANOVA) revealed significant time (F = 84.37, p <  0.001, η_p² = 0.744), condition (F = 22.89, p <  0.001, η_p² = 0.441), and time*condition effects (F = 24.40, p <  0.001, η_p² = 0.457) in blood glucose levels. Respondents (n = 30) who consumed Formulation 3 also had a significantly lower blood glucose 2-hour incremental area under the curve (iAUC) of 134.65 ± 44.51 mmol/L*min and maximum concentration (CMax) of 7.20 (7.10, 8.20) mmol/L with relative reduction of 26.8 and 13.3% respectively, when compared with control (p <  0.001). Besides, significantly greater perceived satiety, lower energy and fat intake as well as higher dietary fiber intake were also observed in the intervention group compared with the placebo group (p <  0.05). There were no marked side effects associated with the ingestion of the test products.

CONCLUSIONS

Short-term consumption of formulated MMT peel powder may improve glycemic response, increase perceived satiety and reduce food intake in adults at risk of type 2 diabetes with the potential to be utilized as a functional beverage. Medium-to long-term clinical trial is warranted to determine whether taking this formulated MMT peel powder on a daily basis has an influence on health outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05298111. Registered 28/03/2022.

Effect of oat supplementation interventions on cardiovascular disease risk markers: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

Oat supplementation interventions (OSIs) may have a beneficial effect on cardiovascular disease (CVD) risk. However, dietary background can modulate such effect. This systematic review assesses the effects of OSIs on CVD risk markers among adults, accounting for different dietary backgrounds or control arms.

METHODS

We included randomized clinical trials (RCTs) that assessed the effect of oat, oat beta-glucan-rich extracts or avenanthramides on CVD risk markers.

RESULTS

Seventy-four RCTs, including 4937 predominantly hypercholesterolemic, obese subjects, with mild metabolic disturbances, were included in the systematic review. Of these, 59 RCTs contributed to the meta-analyses. Subjects receiving an OSI, compared to control arms without oats, had improved levels of total cholesterol (TC) [weighted mean difference and (95% CI) - 0.42 mmol/L, (- 0.61; - 0.22)], LDL cholesterol [- 0.29 mmol/L, (- 0.37; - 0.20)], glucose [- 0.25 nmol/L, (- 0.36; - 0.14)], body mass index [- 0.13 kg/m2, (- 0.26; - 0.01)], weight [- 0.94 kg, (- 1.84: - 0.05)], and waist circumference [- 1.06 cm, (- 1.85; - 0.27)]. RCTs on inflammation and/or oxidative stress markers were scarce and with inconsistent findings. RCTs comparing an OSI to heterogeneous interventions (e.g., wheat, eggs, rice, etc.), showed lowered levels of glycated haemoglobin, diastolic blood pressure, HDL cholesterol and apolipoprotein B. The majority of included RCTs (81.1%) had some concerns for risk of bias.

CONCLUSION

Dietary OSIs resulted in lowered levels of blood lipids and improvements in anthropometric parameters among participants with predominantly mild metabolic disturbances, regardless of dietary background or control. Further high-quality trials are warranted to establish the role of OSIs on blood pressure, glucose homeostasis and inflammation markers.

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].

Postprandial Glucose Response after Consuming Low-Carbohydrate, Low-Calorie Rice Cooked in a Carbohydrate-Reducing Rice Cooker

This study evaluates whether blood glucose response differs upon consuming rice cooked in a carbohydrate (carb)-reducing rice cooker. Rice cooked this way exhibited 19% reduced total carbohydrate (34.0 ± 0.3 vs. 27.6 ± 0.9 g/100 g rice) and 20% reduced total calorie (149.0 ± 1.0 vs. 120.8 ± 3.7 kcal/100 g rice) contents. We measured the blood glucose response (at 0, 15, 30, 45, 60, 90, and 120 min) in 13 healthy participants after consuming 6 different rice types: regular white rice (regular WR, 50 g of available carbohydrate (AC)), low-carb WR with equivalent weight as regular WR (low-carb WR (EW)), low-carb WR with equivalent carb as regular WR (low-carb WR (EC), regular mixed-grain rice (regular MR), low-carb MR (EW) as regular MR, and low-carb MR (EC) as regular MR. All rice samples were prepared in an electric carb-reducing rice cooker. Postprandial blood glucose, sensory, and appetite were assessed after each test meal. The incremental area under the curve of 15 and 30 min after rice consumption was significantly lower in low-carb WR (EW) than that in regular WR. These results suggest possible health benefits of low-carb WR in reducing early postprandial spikes in blood glucose level without significant differences in satiety and satisfaction.

Use of the β-Glucan-Producing Lactic Acid Bacteria Strains Levilactobacillus brevis and Pediococcus claussenii for Sourdough Fermentation-Chemical Characterization and Chemopreventive Potential of In Situ-Enriched Wheat and Rye Sourdoughs and Breads

The aim of the present study was to examine β-glucan production and the potential prebiotic and chemopreventive effects of wheat and rye sourdoughs and breads generated with wild-type and non-β-glucan-forming isogenic mutant strains of Levilactobacillus brevis and Pediococcus claussenii. Sourdough and bread samples were subjected to in vitro digestion and fermentation. Fermentation supernatants (FS) and pellets (FP) were analyzed (pH values, short-chain fatty acids (SCFA), ammonia, bacterial taxa) and the effects of FS on LT97 colon adenoma cell growth, viability, caspase-2 and -3 activity, genotoxic and antigenotoxic effects and on gene and protein expression of p21, cyclin D2, catalase and superoxide dismutase 2 (SOD2) were examined. Concentrations of SCFA were increased and concentrations of ammonia were partly reduced in the FS. The relative abundance of Bifidobacteriaceae was increased in all FPs. Treatment with FS reduced the growth and viability of LT97 cells and significantly increased caspase-2 and -3 activities without exhibiting genotoxic or antigenotoxic effects. The p21 mRNA and protein levels were increased while that of cyclin D2 was reduced. Catalase and SOD2 mRNA and protein expression were marginally induced. The presented results indicate a comparable chemopreventive potential of wheat and rye sourdoughs and breads without an additional effect of the formed β-glucan.

Viscosity development from oat bran β-glucans through in vitro digestion is lowered in the presence of phenolic compounds

Dietary fibres have been shown to aggregate and lose viscosity and water binding capacity in solution in the presence of phenolic compounds. This study aimed to verify this observation in a complex grain system containing β-glucans. The viscosity of uncooked and cooked oat bran digested in vitro was measured in the presence of 1-30 mM phenolic acids or flavonoids, and digestograms were modelled to understand the effects of phenolic compounds on the drivers of viscosity. The final viscosity of the digesta, driven by β-glucans, underwent a significant decrease of up to 31% upon the addition of phenolic compounds. To account for the inhibitory activity of phenolic compounds on digestive enzymes, modelling of the digestograms was adjusted with reference to that from previous work. The models suggest that phenolic compounds can simultaneously: (1) slow down the release of β-glucans by slowing down digestion through enzyme inhibition, and (2) decrease the viscosity of solubilised β-glucans, likely through colloidal aggregation as observed in solution before. These in vitro results suggest that the health benefits of oats linked to digestive viscosity of β-glucans may be altered by co-formulation with or co-ingestion of phenolic compounds.

A randomised controlled trial of a probiotic and a prebiotic examining metabolic and mental health outcomes in adults with pre-diabetes

AIMS

To evaluate the effect of the probiotic Lactobacillus rhamnosus HN001 and/or cereal enriched with oat-derived beta-glucan (OBG) on metabolic and mental health outcomes when administered to adults with pre-diabetes.

DESIGN

2×2 factorial design randomised, parallel-groups placebo-controlled; double-blinded for probiotic, single-blinded for cereals.

PARTICIPANTS

Community-dwelling adults aged 18-80 years with pre-diabetes: glycated haemoglobin (HbA_1c) 41-49 mmol/mol.

INTERVENTIONS

Capsules containing Lactobacillus rhamnosus (HN001) (6×10⁹ colony-forming units/day), or placebo capsules; and cereal containing 4 g/day OBG or calorie-matched control cereal, taken daily, for 6 months. Study groups were: (A) HN001 capsules+OBG cereal; (B) HN001 capsules+control cereal; (C) placebo capsules+OBG cereal and (D) placebo capsules+control cereal.

OUTCOME MEASURES

Primary outcome: HbA_1c at 6 months.

SECONDARY OUTCOMES

fasting plasma glucose, fasting insulin, homeostatic model assessment of insulin resistance, fasting lipids, blood pressure, body weight, waist circumference, body mass index and mental well-being.

RESULTS

153 participants were randomised. There was complete HbA_1c outcome data available for 129 participants. At 6 months the mean (SD) HbA_1c was 45.9 (4.4) mmol/mol, n=66 for HN001, and 46.7 (4.3) mmol/mol, n=63 for placebo capsules; 46.5 (4.0) mmol/mol, n=67 for OBG and 46.0 (4.6) mmol/mol n=62 for control cereal. The estimated difference between HN001-placebo capsules was -0.83, 95% CI -1.93 to 0.27 mmol/mol, p=0.63, and between OBG-control cereals -0.17, 95% CI -1.28 to 0.94 mmol/mol, p=0.76. There was no significant interaction between treatments p=0.79. There were no differences between groups or significant interactions between treatments for any of the secondary outcomes.

CONCLUSIONS

This study found no evidence of clinical benefit from the supplementation with either HN001 and/or cereal containing 4 g OBG on HbA_1c and all secondary outcomes relevant to adults with pre-diabetes.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clincial Trials Registry number ACTRN12617000990325.

Functionality of oat fiber concentrate and faba bean protein concentrate in plant-based substitutes for minced meat

Oat has been recognized for its health-promoting fiber, β-glucan, while protein-rich faba bean has remained underutilized in Nordic countries despite its good nutritional quality. This research investigated the functionality of oat fiber concentrate and faba bean protein concentrate in plant-based substitutes for minced meat (SMs). The resulting product aimed at mimicking the mechanical and physicochemical characteristics of beef minced meat (BM) and its applications (i.e., fried and burger patty). In this regard, the mechanical properties (e.g., chewiness, Young's modulus) of original/fried SMs were comparable to or higher than those of original/fried BM. SM patties (45% SMs) were structurally weaker than beef burger patties (100% BM). The rheological analysis showed that the presence of oat fiber concentrate increased the gel-like properties of the blend, which correlated with the overall strength of original SMs (e.g., Young's modulus). The results suggested that SMs could be used as BM for the preparation of vegetarian meat-like products.

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SMs containing up to 36% dietary fiber—the half being β-glucan—were obtained.

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Oat-fiber- and faba-bean-protein-concentrate were successfully combined into SMs.

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SMs were mechanically comparable to beef minced meat.

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Patties containing SMs were softer than beef patties.

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Oat fiber concentrate increased the gel-like properties of the blend.

Evaluation of the acute, sub-chronic and chronic oral toxicity, genetic toxicity, and safety of a Lomens-P0

Extracts of Hordeum vulgare and Chrysanthemum zawadskii, two traditional herbal medicines, have long been used to treat women's diseases. Our previous studies have confirmed that these extracts could help relieve the symptoms of premenstrual syndrome by inhibiting prolactin release. A mixture of these natural products was named Lomens-P0. In this study, we conducted three genotoxicity tests (bacterial reverse mutation, mammalian chromosome aberration, and mammalian erythrocyte micronucleus studies) and four oral toxicity tests (single-dose, 2-week repeated-dose, and 13-week repeated-dose studies in rodents, and a single-dose dose-escalation toxicity study in a non-rodent model) to confirm the potential toxicity and safety of Lomens-P0. The results of this series of tests indicated Lomens-P0 did not induce genotoxicity, and the NOAEL for the rodent was 2000 mg/kg BW/day. Similarly, no toxic effects were evident in the single-dose-escalation study in the non-rodent model. In conclusion, we confirmed that Lomens-P0 might have potential utility as a raw material for nutraceuticals and natural medicines.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s43188-021-00090-5.

Whole grain intake, compared to refined grain, improves postprandial glycemia and insulinemia: a systematic review and meta-analysis of randomized controlled trials

Whole grain (WG) intake has been associated with reduced risk of type 2 diabetes (T2D) and may protect against T2D by lowering postprandial glycemia and insulinemia and improving insulin sensitivity. The objective of this systematic review and meta-analysis was to evaluate the effect of WG intake, compared to refined grain (RG) intake, on postprandial glycemia and insulinemia and markers of glycemic control and insulin resistance in randomized controlled trials (RCTs) in adults. A search of PubMed and Scopus yielded 80 relevant RCTs. Compared to RG, WG intake significantly reduced postprandial glycemia (SMD: -0.30; 95% CI: -0.43, -0.18; P < 0.001), insulinemia (SMD: -0.23; 95% CI: -0.35, -0.10; P < 0.001) and glycated hemoglobin (HbA1c) (SMD: -0.21; 95% CI: -0.37, -0.06; P = 0.007). There was no effect of WG on fasting glucose, fasting insulin, or homeostatic model assessment of insulin resistance (HOMA-IR). These results suggest WG foods improve short-term glycemia and insulinemia, which may improve HbA1c, a marker of long-term glycemic control. This may partially explain the inverse association between WG intake and risk of T2D, but further investigations are needed to understand if short-term reductions in glycemia translate to longer term benefits in reducing the risk of T2D.Systematic Review Registration: PROSPERO Registration CRD42020180069.

Nutraceuticals and Herbal Food Supplements for Weight Loss: Is There a Prebiotic Role in the Mechanism of Action?

Numerous nutraceuticals and botanical food supplements are used with the intention of modulating body weight. A recent review examined the main food supplements used in weight loss, dividing them according to the main effects for which they were investigated. The direct or indirect effects exerted on the intestinal microbiota can also contribute to the effectiveness of these substances. The aim of this review is to evaluate whether any prebiotic effects, which could help to explain their efficacy or ineffectiveness, are documented in the recent literature for the main nutraceuticals and herbal food supplements used for weight loss management. Several prebiotic effects have been reported for various nutraceutical substances, which have shown activity on Bifidobacterium spp., Lactobacillus spp., Akkermansia muciniphila, Faecalibacterium prausnitzi, Roseburia spp., and the Firmicutes/Bacteroidetes ratio. Different prebiotics have beneficial effects on weight and the related metabolic profile, in some cases even acting on the microbiota with mechanisms that are completely independent from those nutraceuticals for which certain products are normally used. Further studies are necessary to clarify the different levels at which a nutraceutical substance can exert its action.

Configured for the Human Gut Microbiota: Molecular Mechanisms of Dietary β-Glucan Utilization

The β-glucans are a disparate group of structurally diverse polysaccharides, whose members are widespread in human diets as components of the cell walls of plants, algae, and fungi (including yeasts), and as bacterial exopolysaccharides. Individual β-glucans from these sources have long been associated with positive effects on human health through metabolic and immunological effects. Remarkably, the β-configured glucosidic linkages that define these polysaccharides render them inaccessible to the limited repertoire of digestive enzymes encoded by the human genome. As a result, the various β-glucans become fodder for the human gut microbiota (HGM) in the lower gastrointestinal tract, where they influence community composition and metabolic output, including fermentation to short chain fatty acids (SCFAs). Only recently, however, have the specific molecular systems that enable the utilization of β-glucans by select members of the HGM been fully elucidated by combined genetic, biochemical, and structural biological approaches. In the context of β-glucan structures and their effects on human nutrition and health, we summarize here the functional characterization of individual polysaccharide utilization loci (PULs) responsible for the saccharification of mixed-linkage β(1→3)/β(1→4)-glucans, β(1→6)-glucans, β(1→3)-glucans, β(1→2)-glucans, and xyloglucans in symbiotic human gut bacteria. These exemplar PULs serve as well-defined biomarkers for the prediction of β-glucan metabolic capability in individual bacterial taxa and across the global human population.

Pleurotus eryngii improves postprandial glycaemia, hunger and fullness perception, and enhances ghrelin suppression in people with metabolically unhealthy obesity

The aim of this study was to examine potential postprandial benefits of Pleurotus eryngii in nineteen volunteers with metabolically unhealthy obesity. An acute, randomized, crossover-designed trial comparing a meal with Pleurotus eryngii and a control meal was performed. The two meals matched in macronutrient and caloric content. Participants consumed both meals in random order after an overnight fast. Blood samples were drawn before and 30, 60, 90, 120, 150 and 180 min after meal consumption (in total 266 samples) to determine glucose, insulin, ghrelin, peptide YY, glucagon-like peptide-1 and glicentin. Visual analog scales measuring the subjective perception of hunger and fullness were completed at the same time points. The test meal resulted in lower glucose incremental area under the curve (iAUC). Additionally, the iAUC of the ghrelin response over time was substantially lower after the test meal (p = 0.033). Lower desire to eat and higher fullness was reflected by significantly lower hunger iAUC (p = 0.046) and higher fullness iAUC (p = 0.042) after the test meal. No differences in insulin, PYY, GLP-1 and glicentin were observed. Pleurotus eryngii can ameliorate postprandial glycaemia, appetite and regulate ghrelin levels at the postprandial state. This effect is attributed to the bioactive polysaccharides that inhibit the activity of enzymes catalysing carbohydrate hydrolysis, cause a delayed gastric emptying and glucose absorption.

Fermentation profile, cholesterol-reducing properties and chemopreventive potential of β-glucans from Levilactobacillus brevis and Pediococcus claussenii - a comparative study with β-glucans from different sources

The aim of the present study was to investigate whether β-glucans obtained from the lactic acid bacteria (LAB) Levilactobacillus (L.) brevis and Pediococcus (P.) claussenii exhibit similar physiological effects such as cholesterol-binding capacity (CBC) as the structurally different β-glucans from oat, barley, and yeast as well as curdlan. After in vitro fermentation, fermentation supernatants (FSs) and/or -pellets (FPs) were analyzed regarding the concentrations of short-chain fatty acids (SCFAs), ammonia, bile acids, the relative abundance of bacterial taxa and chemopreventive effects (growth inhibition, apoptosis, genotoxicity) in LT97 colon adenoma cells. Compared to other glucans, the highest CBC was determined for oat β-glucan (65.9 ± 8.8 mg g^-1, p < 0.05). Concentrations of SCFA were increased in FSs of all β-glucans (up to 2.7-fold). The lowest concentrations of ammonia (down to 0.8 ± 0.3 mmol L^-1) and bile acids (2.5-5.2 μg mL^-1) were detected in FSs of the β-glucans from oat, barley, yeast, and curdlan. The various β-glucans differentially modulated the relative abundance of bacteria families and reduced the Firmicutes/Bacteroidetes ratio. Treatment of LT97 cells with the FSs led to a significant dose-dependent growth reduction and increase in caspase-3 activity without exhibiting genotoxic effects. Though the different β-glucans show different fermentation profiles as well as cholesterol- and bile acid-reducing properties, they exhibit comparable chemopreventive effects.

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.

Process-Induced Changes in the Quantity and Characteristics of Grain Dietary Fiber

Daily use of wholegrain foods is generally recommended due to strong epidemiological evidence of reduced risk of chronic diseases. Cereal grains, especially the bran part, have a high content of dietary fiber (DF). Cereal DF is an umbrella concept of heterogeneous polysaccharides of variable chemical composition and molecular weight, which are combined in a complex network in cereal cell walls. Cereal DF and its distinct components influence food digestion throughout the gastrointestinal tract and influence nutrient absorption and other physiological reactions. After repeated consumption of especially whole grain cereal foods, these effects manifest in well-demonstrated health benefits. As cereal DF is always consumed in the form of processed cereal food, it is important to know the effects of processing on DF to understand, safeguard and maximize these health effects. Endogenous and microbial enzymes, heat and mechanical energy during germination, fermentation, baking and extrusion destructurize the food and DF matrix and affect the quantity and properties of grain DF components: arabinoxylans (AX), beta-glucans, fructans and resistant starch (RS). Depolymerization is the most common change, leading to solubilization and loss of viscosity of DF polymers, which influences postprandial responses to food. Extensive hydrolysis may also remove oligosaccharides and change the colonic fermentability of DF. On the other hand, aggregation may also occur, leading to an increased amount of insoluble DF and the formation of RS. To understand the structure–function relationship of DF and to develop foods with targeted physiological benefits, it is important to invest in thorough characterization of DF present in processed cereal foods. Such understanding also demands collaborative work between food and nutritional sciences.

Structural Studies of Water-Insoluble β-Glucan from Oat Bran and Its Effect on Improving Lipid Metabolism in Mice Fed High-Fat Diet

Water-insoluble β-glucan has been reported to have beneficial effects on human health. However, no studies have thoroughly characterized the structure and function of water-insoluble β-glucan in oat bran. Thus, the structure and effect of water-insoluble β-glucan on weight gain and lipid metabolism in high-fat diet (HFD)-fed mice were analyzed. First, water-insoluble β-glucan was isolated and purified from oat bran. Compared with water-soluble β-glucan, water-insoluble β-glucan had higher DP3:DP4 molar ratio (2.12 and 1.67, respectively) and molecular weight (123,800 and 119,200 g/mol, respectively). Notably, water-insoluble β-glucan exhibited more fibrous sheet-like structure and greater swelling power than water-soluble β-glucan. Animal experiments have shown that oral administration of water-insoluble β-glucan tended to lower the final body weight of obese mice after 10 weeks treatment. In addition, water-insoluble β-glucan administration significantly improved the serum lipid profile (triglyceride, total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol levels) and epididymal adipocytes size. What is more, water-insoluble β-glucan reduced the accumulation and accelerated the decomposition of lipid in liver. In conclusion, water-insoluble β-glucan (oat bran) could alleviate obesity in HFD-fed mice by improving blood lipid level and accelerating the decomposition of lipid.

Novel Steroidal Saponins in Oat Identified by Molecular Networking Analysis and Their Levels in Commercial Oat Products

Through the use of the Global Natural Product Social (GNPS) feature-based networking system, a series of newly identified steroidal saponins were discovered in oat. The structures of the three new major steroidal saponins, sativacosides A-C (1-3), were characterized by analyzing their high-resolution MS, 1D and 2D NMR spectra, and an additional eight new steroidal saponins were also tentatively identified (4-11) based on their tandem mass spectra and typical fragments. Using ultrahigh-performance liquid chromatography with tandem mass spectrometry techniques, a complete profile of the new sativacoside series was established, and the contents of sativacosides A-C were quantified in 18 different commercial oat products. The total levels of sativacosides A-C varied from 62.2 to 192.9 μg/g in these 18 products, in which oat bran (11 samples) and oatmeal (3 samples) had higher levels than cold oat cereal (4 samples).

Barley-based probiotic food mixture: health effects and future prospects

Consumers around the globe are increasingly aware of the relation between nutrition and health. In this sense, food products that can improve gastrointestinal health such as probiotics, prebiotics and synbiotics are the most important segment within functional foods. Cereals are the potential substrates for probiotic products as they contain nutrients easily assimilated by probiotics and serve as the transporters of Lactobacilli through the severe conditions of gastrointestinal tract. Barley is one of the important substrates for the probiotic formulation because of its high phenolic compounds, β-glucans and tocols. The purpose of this review is to examine recent information regarding barley-based probiotic foods with a specific focus on the potential benefits of barley as a substrate for probiotic microorganisms in the development of dairy and nondairy based food products, and to study the effects of food matrices containing barley β-glucans on the growth and features of Lactobacillus strains after fermentation.

Effect of processing on oat β-glucan viscosity, postprandial glycemic response and subjective measures of appetite

Oat has procured its acclaim as a health promoting food partially due to its positive effect on glucose control. It has been demonstrated that oat β-glucan can interfere with postprandial glucose response. A large majority of this action is attributed to the increase in viscosity due to the β-glucan content in oat foods. While it is known that an increase in viscosity due to higher molecular weight of β-glucan can improve its glycemic effects, it is not known if an increase in viscosity attained by processing variables can further enhance the positive effect of oat on glucose control. In the current study we have examined the effect of kilning, tempering, microwaving, cooking, soaking and flaking on oat β-glucan viscosity. An acute randomized crossover clinical trial was also conducted to test oatmeal products containing low, medium and high β-glucan viscosity for their effect on postprandial glycemic response. Results from the processing experiments demonstrate that kilned samples, when tempered to 25% moisture and microwaved for 2 minutes, can produce much higher final viscosity compared to other samples with similar β-glucan content, molecular weight and solubility. However, results from the clinical trial show that the increase in the viscosity of the oat β-glucan attained through processing in this study did not have any effect on postprandial glucose control.

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.

A Practical Perspective for a Conservative Estimate of Blood Glucose Level during Restaurant Dining and Supermarket Shopping

Foods today are so diverse and enjoyable, making healthy choices difficult. In this perspective, an in vitro-in silico approach for obtaining a conservative estimate of the postprandial blood glucose concentration, which is a realistic estimate nevertheless, after intake of a certain portion of meals is proposed. The rationales and feasibilities of the approach are described and discussed to an extent. The key idea is to first measure the maximum amount of glucose released in an in vitro test under standardized conditions from a specified serving size of a meal or dish or a packaged product sold in a supermarket. The value can then be translated by a literate consumer to the highest estimate of blood glucose rise prior to purchasing or eating through an established in silico blood glucose prediction model in the medical field. The strategy proposed here would help health conscious (diabetics included) and other life quality conscious individuals to make quantitative decisions on consuming the portions of different foods of desire. This strategy may be more effective in reality compared to the conventional GI (Glycemic Index) and GL (Glycemic Load) concepts.

Emerging science on benefits of whole grain oat and barley and their soluble dietary fibers for heart health, glycemic response, and gut microbiota

The aim of this work is to review the major mechanisms by which consumption of whole grain oats and barley, and β-glucans, reduces the risk of coronary heart disease, type 2 diabetes, and other noncommunicable chronic conditions. These effects have been predominantly explained by the role of soluble dietary fibers and smaller bioactive compounds, such as phenolic compounds, in oats and barley. These help to reduce the level of serum low-density lipoprotein cholesterol, decreasing postprandial blood glucose and modulating gut microbiota. In the present review, the role of viscosity development of the intestinal content by β-glucans in these mechanisms is discussed, as well as the impact of processing conditions altering the composition or the physicochemical characteristics of β-glucans.

Effects of Whole Grain Intake, Compared with Refined Grain, on Appetite and Energy Intake: A Systematic Review and Meta-Analysis

Results from observational studies indicate that whole grain (WG) intake is inversely associated with BMI and risk of weight gain. WG intake may influence energy balance and body composition through effects on appetite and energy intake. To evaluate the impact of WG food consumption on appetite and energy intake, a systematic review and meta-analysis was performed of results from randomized controlled trials (RCTs) assessing WG food consumption, appetite, and energy intake in adults. A search of PubMed, Scopus, and Food Science and Technology Abstracts yielded 36 RCTs measuring subjective appetite ratings after consuming WG foods compared with refined grain (RG) controls. Thirty-two of these studies reported AUCs for subjective appetite (hunger, fullness, satiety, desire to eat, or prospective consumption) and/or energy intake and were included in the meta-analysis. Pooled estimates from meta-analyses are expressed as standardized mean differences (SMDs). Compared with RG foods, intake of WG foods resulted in significant differences in AUCs for subjective hunger (SMD: -0.34; 95% CI: -0.46, -0.22; P < 0.001), fullness (SMD: 0.49; 95% CI: 0.31, 0.66; P < 0.001), satiety (SMD: 0.33; 95% CI: 0.18, 0.47; P < 0.001), and desire to eat (SMD: -0.33; 95% CI: -0.46, -0.20; P < 0.001). There were small, nonsignificant reductions in prospective consumption ratings (P = 0.08) and energy intake (P = 0.07) with WG intake compared with RG. These results support the view that consumption of WG foods, compared with RG foods, significantly impacts subjective appetite, and might partly explain the inverse associations between WG food intake and risk of overweight, obesity, and weight gain over time. PROSPERO registration: CRD42020148217.

Thermal Processing has no Impact on Chemopreventive Effects of Oat and Barley Kernels in LT97 Colon Adenoma Cells

The unique dietary fiber composition with high contents of β-glucan contributes to the health-promoting properties of oat and barley and may mediate a reduction of colon cancer risk. In the present study, chemopreventive effects of oat and barley (beta^®barley) kernels were investigated. In order to address the impact of thermal processing on these effects, kernels were roasted (150-180 °C, approx. 20 min), digested and fermented using an In Vitro human digestion model. Concentrations of short-chain fatty acids (SCFA) and ammonia were determined in fermentation supernatants (FS). Growth inhibition, apoptosis, DNA integrity and gene expression of catalase were analyzed in LT97 colon adenoma cells. Concentrations of SCFA, particularly butyrate, were higher in oat/barley FS (2.2-fold, on average), while ammonia levels were significantly lower (0.7-fold, on average) than in the fermentation control. Treatment of LT97 cells with FS of oat/barley kernels led to a significant time- and dose-dependent growth reduction, a significant increase in caspase-3 activity and enhanced levels of catalase mRNA, without exhibiting genotoxic effects. In general, the results indicate a chemopreventive potential of In Vitro fermented oat and waxy winter barley mediated mainly by growth inhibitory and apoptotic effects, which are preserved after thermal processing.

Impact of processing degree on fermentation profile and chemopreventive effects of oat and waxy barley in LT97 colon adenoma cells

The chemopreventive effects of β-glucan-rich cereals such as oat and barley (beta®barley) have been examined previously, but studies comparing fermentation characteristics and chemopreventive effects of oat and barley of different processing stages are rare. Therefore, the present study aims at investigating the fermentation end points (pH values, concentrations of short-chain fatty acids (SCFA) and ammonia) in fermentation supernatants (FS) obtained from differently processed oat and barley samples (kernels, thick and thin flakes). Chemopreventive effects of FS, such as growth inhibition, apoptosis, and induction of cell cycle- and redox-relevant genes (p21, SOD2), were analysed in LT97 colon adenoma cells. After fermentation, pH values were reduced (∆ pH − 1.3, on average) and SCFA concentrations were increased (∆ + 59 mmol/L, on average) with a shift towards butyrate formation in FS obtained from oat and barley samples compared to the fermentation negative control (FS blank). Ammonia was reduced more effectively in FS obtained from barley (∆ − 4.6 mmol/L, on average) than from oat samples (∆ − 1.0 mmol/L, on average). Treatment of LT97 cells with FS resulted in a time- and dose-dependent reduction of cell number, an increase in caspase-3 activity (up to 9.0-fold after 24 h, on average) and an induction of p21 (2.1-fold, on average) and SOD2 (2.3-fold, on average) mRNA expression, while no genotoxic effects were observed. In general, the results indicate no concrete effect of the type of cereal or processing stage on fermentation and chemopreventive effects of oat and barley.

Quantitative Analysis and Anti-inflammatory Activity Evaluation of the A-Type Avenanthramides in Commercial Sprouted Oat Products

Avenanthramides (AVAs) are unique phytochemicals in oat that contain two distinct groups of compounds. The first group is constituted by N-cinnamoylanthranilic acids with a single double bond (referred to as C type), and the other group is constituted by N-avenalumoylanthranilic acids with two double bonds (referred to as A type). C-type AVAs have been reported with their chemical profiles and levels in commercial oat products as well as their bioactivities. However, the accurate levels of A-type AVAs in commercial sprouted oat products and their bioactivity are still unknown. In this study, we purified seven A-type AVAs from sprouted oat bran and characterized their structures with corresponding mass spectrometry and nuclear magnetic resonance data. Among them, five compounds were isolated from oat bran for the first time. The purified A-type AVAs were used as authentic standards to establish the chemical profile of A-type AVAs in oat and to quantify the levels of all individual A-type AVAs in six commercial sprouted oat products using ultra-high-performance liquid chromatography with tandem mass spectrometry. The total A-type AVA contents in the various oat products ranged from 7.85 to 133.3 μg/g. Furthermore, the inhibition of lipopolysaccharide-induced nitric oxide production and inducible nitric oxide synthase expression by A- and C-type AVAs in macrophages were compared. The most abundant A-type AVAs (2p_d, 2c_d, and 2f_d) have similar anti-inflammatory activity to the major C-type AVAs (2p, 2c, and 2f). To the best of our knowledge, this is the first report on the bioactivity of A-type AVAs.

Quantitative characterization of the digestive viscosity profile of cereal soluble dietary fibers using in vitro digestion in Rapid ViscoAnalyzer

A standard method measuring viscosity (η) of cereal products through in vitro digestion in a Rapid ViscoAnalyzer has been developed previously and is predictive of some physiological effects of cereal foods. This paper proposes a simple mathematical model to analyze quantitatively the digestograms obtained by that method. Digestograms of twelve uncooked and cooked cereal products were generated and data quality was assessed. Experimental data were fitted with a viscosity model η_model=η₁+η₂, where [Formula: see text] and [Formula: see text] were respectively viscosity decrease and viscosity increase components. The model showed very good agreement with experimental data and enabled interpretation of the digestograms in relation to the composition of the products: η₁ was interpreted as the decreasing viscosity of digestible polymeric nutrients whereas η₂ was interpreted as the viscosity development of viscous dietary fibers. This model may be useful to investigate quantitatively the biological effects of soluble dietary fibers in cereal products and similar products.

The effect of beta-glucan supplementation on glycemic control and variability in adolescents with type 1 diabetes mellitus

AIMS

This study aimed to investigate whether supplemental soluble fiber, oat β-glucan, has any effect on glycemic control and variability of adolescents with type 1 diabetes mellitus.

METHODS

This study was conducted in 30 adolescents with type 1 diabetes mellitus and it consisted of three phases lasting one week. At Phase I, all subjects followed a standard diet program. For Phase II and Phase III, the subjects continued their standard diet program and added natural oat flakes containing 3 g/day and 6 g/day β-glucan, respectively. Glucose levels were monitored by continuous glucose monitoring (CGM). The maximal, minimal, mean and daytime and night blood glucose levels, percentages of glucose values in a target range and below and above a target values were calculated for each of the phases. Premeal, postmeal, peak blood glucose values and peak times of meals were evaluated for each of the phases. Glycemic variability was measured via SD, CV, MAGE, IQR, MODD, LBGI, HBGI, and CONGA parameters.

RESULTS

The maximal, mean and daytime and night blood glucose levels were the lowest at Phase III (p < 0.05). Minimal blood glucose levels were the highest at Phase III (p < 0.05). Phase I, II, and III showed similar durations elapsed for Level 2 and Level 1 hypoglycemia, euglycemia, Level 1 and Level 2 hyperglycemia (p > 0.05). Premeal and postmeal blood glucose levels were lowest at Phase III for breakfast, lunch, and overall (p < 0.05). The lowest peak blood glucose levels were detected at Phase III for breakfast, lunch, dinner and overall (p < 0.05). Phase III also showed delayed peaks for all time-points (p < 0.05 for each) compared to other phases. Phase III had significantly lower levels of SD, CV, LBGI, and CONGA levels than those in either Phase I or Phase II (p < 0.05 for each).

CONCLUSION

6 g/day oat β-glucan have favorable outcomes in glycemic control and variability in adolescents with type 1 diabetes mellitus.

Effect of Different Amounts of Hybrid Barley in Diets on the Growth Performance and Selected Biochemical Parameters of Blood Serum Characterizing Health Status in Fattening Pigs

Simple Summary

The aim of the present study was to determine the effect of dietary hybrid barley and/or wheat on production parameters, selected biochemical parameters of blood serum characterizing health status in fattening pigs. The use of hybrid barley as the basic ingredient of diets for fattening pigs provided similar production parameters as those obtained with wheat. No significant differences were noted in case of performance results and meatiness of fatteners. However, usage of hybrid barley with high level in diet decreased level of total cholesterol and LDL (low-density lipoprotein fraction) fraction in blood. It means that barley had a beneficial effect on blood lipid indices.

Abstract

The aim of the study was to determine the effect of dietary hybrid barley and/or wheat on production parameters, selected biochemical parameters of blood serum characterizing health status in fattening pigs. In group I, hybrid barley constituted 80% of feed; in II—wheat and hybrid barley were used, each in amount of 40% feed; in III—contained 80% of wheat. No significant differences were noted in case of performance results (body weight gains, feed intake, and feed conversion ratio) and meatiness of fatteners. All estimated biochemical indices determined in serum were within normal range. Usage of 80% hybrid barley decreased concentration of total cholesterol, low-density lipoprotein fraction (LDL), and triglycerides in blood (p < 0.05). However, high-density lipoprotein fraction (HDL) content increased (p < 0.01) up to 1.04 mmol·dm⁻³, comparing to the group with 80% of wheat (0.84 mmol·dm⁻³). Summarized, the diet with high level of barley had a beneficial effect on blood lipid indices, what indicate a good health status of all animals.

Nutritional value of barley cereal and better opportunities for its processing as a value-added food: a comprehensive review

Barley is one of the most important cereal crops and arranged globally as fourth after wheat, rice, and corn. It is known for its beneficial effects against degenerative diseases including diabetes, obesity, hypertension, and colon inflammation which are associated with eating habits and improper lifestyles. These effects are mainly attributed to its rich dietary fibers, i.e., β-glucan composition. Moreover, barley considered as a good source of starch, minerals, vitamins, and protein pose it as an ideal food supplement. Nevertheless, about 2% of the barley global production is utilized due to unacceptable organoleptic characters. Therefore, continuous modifications are ongoing either to develop new cultivars for different purposes, or novel processing methods to improve its organoleptic characters. In this review, we provide a comprehensive overview of the macroconstituents and microconstituents of barley, its nutritional value and prebiotic effects. Further, different processing procedures performed to improve its organoleptic characters or to decrease its antinutrient levels are outlined with suggestions for further needed cultivars that could preserve the different benefits of barley and maximize its value as a major cereal crop.