Depression of the glycemic index by high levels of beta-glucan fiber in two functional foods tested in type 2 diabetes

Structural and rheological characterization of water-soluble and alkaline-soluble fibers from hulless barley

BACKGROUND

Highland hulless barley has garnered attention as a promising economic product and a potential healthy food ingredient. The present study aimed to comprehensively investigate the molecular structure of extractable fibers obtained from a specific highland hulless barley. Water-soluble fiber (WSF) and alkaline-soluble fiber (ASF) were extracted using enzymatic digestion and an alkaline method, respectively. The purified fibers underwent a thorough investigation for their structural characterization.

RESULTS

The monosaccharide composition revealed that WSF primarily consisted of glucose (91.7%), whereas ASF was composed of arabinose (54.5%) and xylose (45.5%), indicating the presence of an arabinoxylan molecule with an A/X ratio of 1.2. The refined structural information was further confirmed through methylation, 1 H NMR and Fourier-transform infrared spectroscopy analyses. WSF fiber exclusively exhibited α-anomeric patterns, suggesting it was an α-glucan. It has a low molecular weight of 5 kDa, as determined by gel permeation chromatography. Conversely, ASF was identified as a heavily branched arabinoxylan with 41.55% of '→2,3,4)-Xylp-(1→' linkages. ASF and WSF exhibited notable differences in their morphology, water absorption capabilities and rheological properties.

CONCLUSION

Based on these findings, molecular models of WSF and ASF were proposed. The deep characterization of these fiber structures provides valuable insights into their physicochemical and functional properties, thereby unlocking their potential applications in the food industry. © 2023 Society of Chemical Industry.

Tremella fuciformis beverage improves glycated hemoglobin A1c and waist circumference in overweight/obese prediabetic subjects: a randomized controlled trial

BACKGROUND

Prediabetes is increasing worldwide. Previous studies have demonstrated the potential of β-glucan derived from oat or barley to lower blood glucose, body weight, and plasma lipid levels. These findings offer a potentially attractive strategy for reducing the risk of diabetes in prediabetic individuals. However, the effects of β-glucan from Tremella fuciformis on glucose metabolism and anthropometric measurements in humans have yet to be studied. We hypothesized that β-glucan from Tremella fuciformis may improve metabolic parameters in subjects with prediabetes. This study aimed to investigate the effects of a once-daily beverage containing Tremella fuciformis (snow mushroom) on anthropometric measurements, metabolic biomarkers, and insulin sensitivity in overweight/obese subjects with prediabetes.

METHODS

In this double-blind RCT, 56 participants were randomly assigned to receive either a Tremella fuciformis beverage or placebo daily for 12 weeks. All parameters were assessed at baseline and after the intervention.

RESULTS

After 12 weeks, participants in the intervention group exhibited significant improvements in glycated hemoglobin A1c (HbA1C; 6.03 ± 0.26% at baseline vs. 5.96 ± 0.25% at 12 weeks, p = 0.047, Cohen's d = 0.39) and waist circumference (95.2 ± 12.51 cm at baseline vs. 93.46 ± 11.48 cm at 12 weeks, p = 0.022, Cohen's d = 0.45). There were no adverse events reported.

CONCLUSION

This exploratory study demonstrated that Tremella fuciformis beverage consumption may improve HbA1C and waist circumference in overweight/obese prediabetic individuals. Further research, including larger-scale RCTs and mechanistic studies, is needed to confirm these findings and optimize the therapeutic potential of Tremella fuciformis derivatives in managing prediabetes and preventing type 2 diabetes.

TRIAL REGISTRATION

Registered in Thai Clinical Trials Registry (14/07/2021, TCTR20210714004).

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.

From Petri Dish to Field: Plant Tissue Culture and Genetic Engineering of Oats for Improved Agricultural Outcomes

Oats (Avena sativa) hold immense economic and nutritional value as a versatile crop. They have long been recognized as an exceptional choice for human consumption and animal feed. Oats' unique components, including proteins, starches, and β-glucans, have led to its widespread use in various food products such as bread, noodles, flakes, and milk. The popularity of oat milk as a vegan alternative to dairy milk has soared due to the increasing number of vegetarians/vegans and growing environmental awareness. Oat milk offers a sustainable option with reduced greenhouse gas emissions during its production, rendering it an appropriate choice for individuals who are lactose-intolerant or have dairy allergies. To ensure improved adaptability and enhanced nutrition, the development of new oat varieties is crucial, considering factors like cultivation, climate, and growing conditions. Plant cell culture plays a crucial role in both traditional and contemporary breeding methods. In classical breeding, plant cell culture facilitates the rapid production of double haploid plants, which can be employed to accelerate the breeding process. In modern breeding methods, it enables genetic manipulation and precise genome editing at the cellular level. This review delves into the importance of oats and their diverse applications, highlighting the advantages of plant cell culture in both classical and modern breeding methods. Specifically, it provides an overview of plant tissue culture, encompassing genetic transformation, haploid technology, protoplast technology, and genome editing.

Changes in physio-biochemical parameters and expression of metallothioneins in Avena sativa L. in response to drought

Drought is one of the major threats to food security. Among several mechanisms involved in plant stress tolerance, one protein family-the plant metallothioneins (MTs)-shows great promise for enhancing drought resistance. Plant metallothioneins in oat (Avena sativa L.) have not yet been deeply analysed, and the literature lacks a comprehensive study of the whole family of plant MTs in response to drought. In this study, we showed that the number and nature of cis-elements linked with stress response in promoters of AsMTs1-3 differed depending on the MT type. Drought stress in oat plants caused an increase in the expression of AsMT2 and AsMT3 and a decrease in the expression of AsMT1 compared to well-watered plants. Moreover, the low values of relative water content, water use efficiency, net photosynthesis (P_N), transpiration (E), stomatal conductance (g_s), chlorophyll a, and carotenoid were accompanied by high levels of electrolyte leakage, internal CO₂ concentration (C_i) and abscisic acid content, and high activity of antioxidants enzymes in plants under drought stress. The present study puts forward the idea that AsMTs are crucial for oat response to drought stress not only by regulating antioxidant activity but also by changing the plant water regime and photosynthesis. Our results support the hypothesis that structural differences among types of plant MTs reflect their diversified physiological roles.

The comparison of polymorphism among Avena species revealed by retrotransposon-based DNA markers and soluble carbohydrates in seeds

Here, we compared the polymorphism among 13 Avena species revealed by the iPBS markers and soluble carbohydrate profiles in seeds. The application of seven iPBS markers generated 83 bands, out of which 20.5% were polymorphic. No species-specific bands were scored. Shannon's information index (I) and expected heterozygosity (H_e) revealed low genetic diversity, with the highest values observed for A. nuda (I = 0.099; He = 0.068). UPGMA clustering of studied Avena accessions and PCoA results showed that the polyploidy level is the main grouping criterion. High-resolution gas chromatography revealed that the studied Avena accessions share the same composition of soluble carbohydrates, but significant differences in the content of total (5.30-22.38 mg g^-1 of dry weight) and particular sugars among studied samples were observed. Sucrose appeared as the most abundant sugar (mean 61.52% of total soluble carbohydrates), followed by raffinose family oligosaccharides (31.23%), myo-inositol and its galactosides (6.16%), and monosaccharides (1.09%). The pattern of interspecific variation in soluble carbohydrates, showed by PCA, was convergent to that revealed by iPBS markers. Thus, both methods appeared as a source of valuable data useful in the characterization of Avena resources or in the discussion on the evolution of this genus.

Cow's Milk in Human Nutrition and the Emergence of Plant-Based Milk Alternatives

Cow's milk is considered a complete food, providing high-quality protein and essential micronutrients, including vitamins and minerals. For medical reasons or as a lifestyle choice, consumers are replacing cow's milk with plant-based milk alternatives (PBMA); some perceive them as healthier alternatives to cow's milk due to their low saturated fatty acid content and no cholesterol content. However, the nutritional composition of PBMA is quite variable between different types and even within, which makes a comparison with cow's milk a complex issue. Furthermore, the consumption of PBMA has been associated with the development of some diseases in infants and children. Meanwhile, the consumption of cow's milk in human health is a controversial issue since it has been associated with a favorable effect in some diseases (such as obesity, type 2 diabetes, and Alzheimer's) and a negative effect in others (such as prostate cancer risk and Parkinson's disease); while in some diseases, there is no consensus in the cow's milk consumption effect. The aim of this review is to make a nutritional comparison of cow's milk with PBMA and to clarify the potential health issues related to their consumption.

Effect of sorghum and barley-containing bread on plasma total polyphenols, antioxidant status and inflammation in healthy subjects

The aim of this study was to investigate the effect of bread incorporated with whole-grain red sorghum and barley flours on biomarkers of oxidative stress and inflammation in humans. In a randomized cross-over study, 20 healthy subjects consumed either control bread made of all-purpose wheat flour only or bread containing 40% whole-grain red sorghum and barley flours (20% each), with a washout period of 1-2 week. The test breads were fed at breakfast after 12 h fast. Blood samples were collected at baseline (fasting) and 2 h after intake of breads. Plasma total polyphenols, total antioxidant capacity (T-AOC), superoxide dismutase (SOD) activity, thiobarbituric acid reactive substances (TBARS) and highly sensitive C-reactive protein were assessed. Compared to fasting values, the 2 h postprandial levels of plasma total polyphenols (P = 0.001), T-AOC (P = 0.031) and SOD activity (P = 0.026) were significantly higher following consumption of sorghum and barley-containing bread (SBB). Moreover, net changes in plasma total polyphenols (P = 0.001), T-AOC (P = 0.047) and SOD activity (P = 0.035) were significantly higher following consumption of SBB. In conclusion, bread containing whole-grain red sorghum and barely flours enhanced plasma total polyphenols and antioxidant status and hence its consumption would modulate biomarkers of cardio-metabolic health.

Short-Term Effects of Traditional Greek Meals: Lentils with Lupins, Trahana with Tomato Sauce and Halva with Currants and Dried Figs on Postprandial Glycemic Responses-A Randomized Clinical Trial in Healthy Humans

Low glycemic index (GI) diets have been associated with decreased chronic disease risk. In a randomized, cross-over study we investigated the GI and glycemic response to three traditional Greek mixed meals: Lentils, Trahana, and Halva. Twelve healthy, fasting individuals received isoglucidic test meals (25 g available carbohydrate) and 25 g glucose reference, in random order. GI was calculated and capillary blood glucose (BG) samples were collected at 0-120 min after meal consumption. Subjective appetite ratings were assessed. All three tested meals provided low GI values. Lentils GI was 27 ± 5, Trahana GI was 42 ± 6, and Halva GI was 52 ± 7 on glucose scale. Peak BG values were lowest for Lentils, followed by Trahana and then by Halva (p for all <0.05). Compared to the reference food, BG concentrations were significantly lower for all meals at all time-points (p for all <0.05). Lentils provided lower glucose concentrations at 30 and 45 min compared to Trahana (p for all <0.05) and at 30, 45, and 60 min compared to Halva (p for all <0.05). BG concentrations did not differ between Trahana and Halva at all time points. No differences were observed for fasting BG, time to peak rise for BG, and subjective appetite ratings. In conclusion, all three mixed meals attenuated postprandial glycemic response in comparison to glucose, which may offer advantages to glycemic control.

Effect and mechanism of glycerol monostearate dimer (GMS-D) and baking-treatment on the structure, in vitro digestion of gelatinized potato starch-GMS-D

With the increasing progress of society and in-depth scientific research, dietary regulations, especially sustained glucose releases, are regarded as an effective and significant way to lighten or even cut the emergence of diabetes. In this research, the starch-lipid complex gelatinized potato starch-glycerol monostearate dimer (GPS-GMS-D) was developed to provide a low-glycemic index functional food component for type 2 diabetes. Briefly, the higher complexation index (CI, 71.02%), lower rapidly digestible starch (RDS, 35.57%), and lower estimated glycemic index (eGI, 52.34%) were referred to as GPS-GMS-D. It was assumed that the solid V-type crystal structure, induced with the helix between GMS-D and GPS due to high amylose, high saturation, and low steric hindrance, contributed to the lower digestibility. In addition, baking treatment for 5 min was systematically exerted to improve the flavor of GPS-GMS-D with a relatively high CI (59.98%) and low eGI (54.15%). It was believed that rapid dehydration and close interaction during baking treatment could slow down the decomposition of GPS-GMS-D and conversions of starch fractions. Therefore, these results suggested that the as-developed GPS-GMS-D was a promising low GI functional dietary food component for diabetes mellitus, and a suitable baking post-thermal treatment was successfully proposed to enhance the flavor of GPS-GMS-D. PRACTICAL APPLICATION: The higher amylose and solid V-type crystal structure in gelatinized potato starch-glycerol monostearate dimer (GPS-GMS-D) would induce the formation of slowly digestive starch (SDS) and resistant starch (RS) to suppress enzymatic hydrolysis. Moreover, the flavor of GPS-GMS-D was enhanced with appropriate and moderate thermal processing (baking), which was likely to improve the quality of life of a person with diabetes. Thus, we believe that GPS-GMS-D is a promising functional food component for diabetes mellitus.

Effects of Spaghetti Differing in Soluble Fiber and Protein Content on Glycemic Responses in Humans: A Randomized Clinical Trial in Healthy Subjects

This randomized, single blind, cross-over study investigated the glycemic responses to three spaghetti No 7 types differing in dietary protein and soluble fiber content. Fourteen clinically and metabolically healthy, fasting individuals (25 ± 1 years; ten women; BMI 23 ± 1 kg/m²) received isoglucidic test meals (50 g available carbohydrate) and 50 g glucose reference, in random order. GI was calculated using the FAO/WHO method. Capillary blood glucose and salivary insulin samples were collected at 0, 15, 30, 45, 60, and 120 min. Subjective appetite ratings (hunger, fullness, and desire to eat) were assessed by visual analogue scales (VAS, 100 mm) at baseline and 120 min. All three spaghetti types (regular, whole wheat, and high soluble fiber–low carbohydrates) provided low GI values (33, 38, and 41, respectively, on glucose scale) and lower peak glucose values compared to glucose or white bread. No differences were observed between spaghetti No 7 types for fasting glucose, fasting and post-test-meal insulin concentrations, blood pressure (systolic and diastolic), and subjective appetite. Conclusions: all spaghetti No 7 types, regardless of soluble fiber and/or protein content, attenuated postprandial glycemic response, which may offer advantages to glycemic control.

Valorization of cereal by-product hemicelluloses: Fractionation and purity considerations

The biomass from cereal side streams is rich in valuable components, such as hemicelluloses. Among the hemicelluloses, arabinoxylans and β-glucans are the most acknowledged for potential health benefits. Numerous publications discuss the potential to use purified forms of these hemicelluloses for various applications. However, as the purification of hemicelluloses may not be economically feasible to upscale, sustainable and cost-effective methods are needed to make their valorization more realistic for industrial applications. Co-components present in hemicellulose-rich fractions may also provide added functionality, such as flavonoid content and antioxidant capacity. This review provides an overview on the feasibility of sustainably upscaling hemicellulose extraction processes, focusing on by-products from different cereal streams. We describe the hemicelluloses' physicochemical properties and provide various possible applications of pure and impure fractions from small scale to pilot and industrial scale. Furthermore, real case examples on the industrial utilization of cereal side streams are enclosed. This review provides pathways for future research for developing the hemicellulose extraction methods to obtain fractions with optimized purity, and offers suggestions to valorize them.

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

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

Oat-Based Foods: Chemical Constituents, Glycemic Index, and the Effect of Processing

The desire for foods with lower glycemic indices has led to the exploration of functional ingredients and novel food processing techniques. The glycemic index (GI) is a well-recognized tool to assess the capacity of foods to raise blood glucose levels. Among cereal crops, oats have shown the greatest promise for mitigating glycemic response. This review evaluated decades of research on the effects of oat components on the GI level of oat-based foods with specific emphasis on oat starch, β-glucans, proteins, and phenolics. The effects of commonly used processing techniques in oats on GI level, including heating, cooling, and germination were also discussed. In addition, the GI of oat-based foods in various physical formats such as whole grain, flakes, and flour was systematically summarized. The aim of this review was to synthesize knowledge of the field and to provide a deeper understanding of how the chemical composition and processing of oats affect GI, thereby further benefiting the development of low-GI oat foods.

Synthesis of functional oligosaccharides and their derivatives through cocultivation and cellular NTP regeneration

Carbohydrates play an important role in the life cycle. Among them, functional oligosaccharides show a complex and diverse structures with unique physiological activities and biological functions. However, different preparation methods directly affect the structure, molecular weight, and other functions of oligosaccharides, as well as their application fields and manufacturing costs. In the preparation of β-1,3-glucan oligosaccharides (OBGs), water insolubility of β-1,3-glucans hampers the hydrolysis efficiency. The synthesis of some functional oligosaccharides requires the consumption of energy substrates, such as ATP, CTP, and uridine triphosphate, for sugar nucleotide synthesis, leading to increased capital costs. A more economical solution to solve energy supply is to adopt microbial cocultivation or cellular nucleoside triphosphate regeneration. This review focused on the sources, preparation methods, biological activities of OBG, and the cultivation methods and applications of microbial cocultivation and fermentation. We also reviewed the preparation methods of other functional oligosaccharides, such as sialylated oligosaccharides, β-nicotinamide mononucleotide, and α-galacto-oligosaccharides.

Insights on the Functional Role of Beta-Glucans in Fungal Immunity Using Receptor-Deficient Mouse Models

Understanding the host anti-fungal immunity induced by beta-glucan has been one of the most challenging conundrums in the field of biomedical research. During the last couple of decades, insights on the role of beta-glucan in fungal disease progression, susceptibility, and resistance have been greatly augmented through the utility of various beta-glucan cognate receptor-deficient mouse models. Analysis of dectin-1 knockout mice has clarified the downstream signaling pathways and adaptive effector responses triggered by beta-glucan in anti-fungal immunity. On the other hand, assessment of CR3-deficient mice has elucidated the compelling action of beta-glucans in neutrophil-mediated fungal clearance, and the investigation of EphA2-deficient mice has highlighted its novel involvement in host sensing and defense to oral mucosal fungal infection. Based on these accounts, this review focuses on the recent discoveries made by these gene-targeted mice in beta-glucan research with particular emphasis on the multifaceted aspects of fungal immunity.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

TRIAL REGISTRATION

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

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.

β-Glucans as a panacea for a healthy heart? Their roles in preventing and treating cardiovascular diseases

Cardiovascular diseases (CVDs) are the leading cause of death worldwide. Factors increasing the risks for CVD development are related to obesity, diabetes, high blood cholesterol, high blood pressure and lifestyle. CVD risk factors may be treated with appropriate drugs, but prolonged can use cause undesirable side-effects. Among the natural products used in complementary and alternative medicines, are the β-ᴅ-glucans; biopolymers found in foods (cereals, mushrooms), and can easily be produced by microbial fermentation. Independent of source, β-glucans of the mixed-linked types [(1 → 3)(1 → 6)-β-ᴅ-glucans - fungal, and (1 → 3)(1 → 4)-β-ᴅ-glucans - cereal] have widely been studied because of their biological activities, and have demonstrated cardiovascular protective effects. In this review, we discuss the roles of β-ᴅ-glucans in various pathophysiological conditions that lead to CVDs including obesity, dyslipidemia, hyperglycemia, oxidative stress, hypertension, atherosclerosis and stroke. The β-glucans from all of the sources cited demonstrated potential hypoglycemic, hypocholesterolemic and anti-obesogenicity activities, reduced hypertension and ameliorated the atherosclerosis condition. More recently, β-glucans are recognized as possessing prebiotic properties that modulate the gut microbiome and impact on the health benefits including cardiovascular. Overall, all the studies investigated unequivocally demonstrated the dietary benefits of consuming β-glucans regardless of source, thus constituting a promising panaceutical approach to reduce CVD risk factors.

β-Glucan Metabolic and Immunomodulatory Properties and Potential for Clinical Application

β-glucans are complex polysaccharides that are found in several plants and foods, including mushrooms. β-glucans display an array of potentially therapeutic properties. β-glucans have metabolic and gastro-intestinal effects, modulating the gut microbiome, altering lipid and glucose metabolism, reducing cholesterol, leading to their investigation as potential therapies for metabolic syndrome, obesity and diet regulation, gastrointestinal conditions such as irritable bowel, and to reduce cardiovascular and diabetes risk. β-glucans also have immune-modulating effects, leading to their investigation as adjuvant agents for cancers (solid and haematological malignancies), for immune-mediated conditions (e.g., allergic rhinitis, respiratory infections), and to enhance wound healing. The therapeutic potential of β-glucans is evidenced by the fact that two glucan isolates were licensed as drugs in Japan as immune-adjuvant therapy for cancer in 1980. Significant challenges exist to further clinical testing and translation of β-glucans. The diverse range of conditions for which β-glucans are in clinical testing underlines the incomplete understanding of the diverse mechanisms of action of β-glucans, a key knowledge gap. Furthermore, important differences appear to exist in the effects of apparently similar β-glucan preparations, which may be due to differences in sources and extraction procedures, another poorly understood issue. This review will describe the biology, potential mechanisms of action and key therapeutic targets being investigated in clinical trials of β-glucans and identify and discuss the key challenges to successful translation of this intriguing potential therapeutic.

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.

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

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

Dietary Fibres and the Management of Obesity and Metabolic Syndrome: The RESOLVE Study

Objectives: This study was performed to evaluate the long-term maintenance of nutritional changes promoted during an intensive initial intervention to induce body weight loss. The ability of these changes to predict long-term health outcomes was also examined. Methods: Nutritional variables, body composition, and metabolic markers collected in the RESOLVE project were analyzed before and after a 3-week intensive diet–exercise intervention (Phase 1), and during a subsequent supervision under free living conditions, of 12 months (Phase 2). Results: As expected, the macronutrient composition of the diet was modified to promote a negative energy balance during Phase 1. The decrease in carbohydrates imposed during this phase was maintained during Phase 2 whereas the increase in protein intake returned to baseline values at the end of the program. Dietary fiber intake was almost doubled during Phase 1 and remained significantly greater than baseline values throughout Phase 2. Moreover, fiber intake was the only nutritional variable that systematically and significantly predicted variations of health outcomes in the study. Conclusion: The adequacy of dietary fiber intake should be a matter of primary consideration in diet-based weight reduction programs.

Current Evidence to Propose Different Food Supplements for Weight Loss: A Comprehensive Review

The use of food supplements for weight loss purposes has rapidly gained popularity as the prevalence of obesity increases. Navigating through the vast, often low quality, literature available is challenging, as is providing informed advice to those asking for it. Herein, we provide a comprehensive literature revision focusing on most currently marketed dietary supplements claimed to favor weight loss, classifying them by their purported mechanism of action. We conclude by proposing a combination of supplements most supported by current evidence, that leverages all mechanisms of action possibly leading to a synergistic effect and greater weight loss in the foreseen absence of adverse events. Further studies will be needed to confirm the weight loss and metabolic improvement that may be obtained through the use of the proposed combination.

Effectiveness of probiotics, prebiotics, and prebiotic-like components in common functional foods

The bioactive ingredients in commonly consumed foods include, but are not limited to, prebiotics, prebiotic-like components, probiotics, and postbiotics. The bioactive ingredients in functional foods have also been associated with beneficial effects on human health. For example, they aid in shaping of gut microflora and promotion of immunity. These functional components also contribute in preventing serious diseases such as cardiovascular malfunction and tumorigenesis. However, the specific mechanisms of these positive influences on human health are still under investigation. In this review, we aim to emphasize the major contents of probiotics, prebiotics, and prebiotic-like components commonly found in consumable functional foods, and we present an overview of direct and indirect benefits they provide on human health. The major contributors are certain families of metabolites, specifically short-chain fatty acids and polyunsaturated fatty acids produced by probiotics, and prebiotics, or prebiotic-like components such as flavonoids, polyphenols, and vitamins that are found in functional foods. These functional ingredients in foods influence the gut microbiota by stimulating the growth of beneficial microbes and the production of beneficial metabolites that, in turn, have direct benefits to the host, while also providing protection from pathogens and maintaining a balanced gut ecosystem. The complex interactions that arise among functional food ingredients, human physiology, the gut microbiota, and their respective metabolic pathways have been found to minimize several factors that contribute to the incidence of chronic disease, such as inflammation oxidative stress.

Genomic insights from the first chromosome-scale assemblies of oat (Avena spp.) diploid species

BACKGROUND

Cultivated hexaploid oat (Common oat; Avena sativa) has held a significant place within the global crop community for centuries; although its cultivation has decreased over the past century, its nutritional benefits have garnered increased interest for human consumption. We report the development of fully annotated, chromosome-scale assemblies for the extant progenitor species of the As- and Cp-subgenomes, Avena atlantica and Avena eriantha respectively. The diploid Avena species serve as important genetic resources for improving common oat's adaptive and food quality characteristics.

RESULTS

The A. atlantica and A. eriantha genome assemblies span 3.69 and 3.78 Gb with an N50 of 513 and 535 Mb, respectively. Annotation of the genomes, using sequenced transcriptomes, identified ~ 50,000 gene models in each species-including 2965 resistance gene analogs across both species. Analysis of these assemblies classified much of each genome as repetitive sequence (~ 83%), including species-specific, centromeric-specific, and telomeric-specific repeats. LTR retrotransposons make up most of the classified elements. Genome-wide syntenic comparisons with other members of the Pooideae revealed orthologous relationships, while comparisons with genetic maps from common oat clarified subgenome origins for each of the 21 hexaploid linkage groups. The utility of the diploid genomes was demonstrated by identifying putative candidate genes for flowering time (HD3A) and crown rust resistance (Pc91). We also investigate the phylogenetic relationships among other A- and C-genome Avena species.

CONCLUSIONS

The genomes we report here are the first chromosome-scale assemblies for the tribe Poeae, subtribe Aveninae. Our analyses provide important insight into the evolution and complexity of common hexaploid oat, including subgenome origin, homoeologous relationships, and major intra- and intergenomic rearrangements. They also provide the annotation framework needed to accelerate gene discovery and plant breeding.

Hydrolysis of beta-glucan in oat flour during subcritical-water extraction

Oat (Avena sativa L.) β-glucan is bound tightly to other components of the endosperm cell wall, which means that β-glucan extraction processes are complex and involve many different stages. Subcritical-water extraction (SWE) has emerged as a promising method for extracting β-glucan under high temperature and pressure conditions. This study investigated the efficiency of the SWE of β-glucan from oat flour. The yield of β-glucan was optimized under the following conditions: extraction temperature of 200 °C, solvent pH of 4.0, extraction time of 10 min, and particle size of 425-850 μm. The extraction yield under the optimal condition was 6.98 ± 1.17 g/100 g oat flour, which was more than twofold higher than when using hot-water extraction at 60 °C for 3 h. β-glucan degradation to 5-hydroxymethyl-2-furaldehyde was increased under high-temperature conditions. SWE is a feasible alternative for extracting β-glucan in a single-step process, and could be developed into an effective industrial process.

Major cereal carbohydrates in relation to intestinal health of monogastric animals: A review

Type, quality, and origin of cereals in diets of poultry and pigs could influence gut microbes and affect their diversity and function, thereby impacting the intestinal function of the monogastric animal. In this review, we focus on the major carbohydrates in cereals that interact directly with gut microbes and lead to the production of key metabolites such as short-chain fatty acids (SCFA), and discuss how cereal fiber impact intestinal health of poultry and pigs. An overview of how the cereals and cereals-derived carbohydrates such as beta-glucans, resistant starch, cellulose, and arabinoxylans could promote intestinal health and reduce the use of in-feed antibiotics in animal production are presented. The metabolic pathway utilized by microbes and the mechanism of action underlying the produced SCFA on intestinal health of monogastric animals is also discussed.

Impact of oat processing on glycaemic and insulinaemic responses in healthy humans: a randomised clinical trial

Oats can be processed in a variety of ways ranging from minimally processed such as steel-cut oats (SCO), to mildly processed such as large-flake oats (old fashioned oats, OFO), moderately processed such as instant oats (IO) or highly processed in ready-to-eat oat cereals such as Honey Nut Cheerios (HNC). Although processing is believed to increase glycaemic and insulinaemic responses, the effect of oat processing in these respects is unclear. Thus, we compared the glycaemic and insulinaemic responses elicited by 628 kJ portions of SCO, OFO, IO and HNC and a portion of Cream of Rice cereal (CR) containing the same amount of available-carbohydrate (23 g) as the oatmeals. Healthy males (n 18) and females (n 12) completed this randomised, cross-over trial. Blood was taken fasting and at intervals for 3 h following test-meal consumption. Glucose and insulin peak-rises and incremental AUC (iAUC) were subjected to repeated-measures ANOVA using Tukey's test (two-sided P&lt;0·05) to compare individual means. Glucose peak-rise (primary endpoint, mean (sem) mmol/l) after OFO, 2·19 (sem 0·11), was significantly less than after CR, 2·61 (sem 0·13); and glucose peak-rise after SCO, 1·93 (sem 0·13), was significantly less than after CR, HNC, 2·49 (sem 0·13) and IO 2·47 (sem 0·13). Glucose iAUC was significantly lower after SCO than CR and HNC. Insulin peak rise was similar among the test meals, but insulin iAUC was significantly less after SCO than IO. Thus, the results show that oat processing affects glycaemic and insulinaemic responses with lower responses associated with less processing.

Clinical and Physiological Perspectives of β-Glucans: The Past, Present, and Future

β-Glucans are a group of biologically-active fibers or polysaccharides from natural sources with proven medical significance. β-Glucans are known to have antitumor, anti-inflammatory, anti-obesity, anti-allergic, anti-osteoporotic, and immunomodulating activities. β-Glucans are natural bioactive compounds and can be taken orally, as a food supplement, or as part of a daily diet, and are considered safe to use. The medical significance and efficiency of β-glucans are confirmed in vitro, as well as using animal- and human-based clinical studies. However, systematic study on the clinical and physiological significance of β-glucans is scarce. In this review, we not only discuss the clinical and physiological importance of β-glucans, we also compare their biological activities through the existing in vitro and animal-based in vivo studies. This review provides extensive data on the clinical study of β-glucans.

Oatmeal particle size alters glycemic index but not as a function of gastric emptying rate

The aim of this study was to determine the extent to which oat particle size in a porridge could alter glucose absorption, gastric emptying, gastrointestinal hormone response, and subjective feelings of appetite and satiety. Porridge was prepared from either oat flakes or oat flour with the same protein, fat, carbohydrate, and mass. These were fed to eight volunteers on separate days in a crossover study, and subjective appetite ratings, gastric contents, and plasma glucose, insulin, and gastrointestinal hormones were determined over a period of 3 h. The flake porridge gave a lower glucose response than the flour porridge, and there were apparent differences in gastric emptying in both the early and late postprandial phases. The appetite ratings showed similar differences between early- and late-phase behavior. The structure of the oat flakes remained sufficiently intact to delay their gastric emptying, leading to a lower glycemic response, even though initial gastric emptying rates were similar for the flake and flour porridge. This highlights the need to take food structure into account when considering relatively simple physiological measures and offering nutritional guidance.NEW & NOTEWORTHY The impact of food structure on glycemic response even in simple foods such as porridge is dependent on both timing of gastric emptying and the composition of what is emptied as well as duodenal starch digestion. Thus structure should be accounted for when considering relatively simple physiological measures and offering nutritional guidance.

Low glycaemic index diets for the prevention of cardiovascular disease

BACKGROUND

The glycaemic index (GI) is a physiological measure of the ability of a carbohydrate to affect blood glucose. Interest is growing in this area for the clinical management of people at risk of, or with, established cardiovascular disease. There is a need to review the current evidence from randomised controlled trials (RCTs) in this area. This is an update of the original review published in 2008.

OBJECTIVES

To assess the effect of the dietary GI on total mortality, cardiovascular events, and cardiovascular risk factors (blood lipids, blood pressure) in healthy people or people who have established cardiovascular disease or related risk factors, using all eligible randomised controlled trials.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase and CINAHL in July 2016. We also checked reference lists of relevant articles. No language restrictions were applied.

SELECTION CRITERIA

We selected RCTs that assessed the effects of low GI diets compared to diets with a similar composition but a higher GI on cardiovascular disease and related risk factors. Minimum trial duration was 12 weeks. Participants included were healthy adults or those at increased risk of cardiovascular disease, or previously diagnosed with cardiovascular disease. Studies in people with diabetes mellitus were excluded.

DATA COLLECTION AND ANALYSIS

Two reviewers independently screened and selected studies. Two review authors independently assessed risk of bias, evaluated the overall quality of the evidence using GRADE, and extracted data following the Cochrane Handbook for Systematic Reviews of Interventions. We contacted trial authors for additional information. Analyses were checked by a second reviewer. Continuous outcomes were synthesized using mean differences and adverse events were synthesized narratively.

MAIN RESULTS

Twenty-one RCTs were included, with a total of 2538 participants randomised to low GI intervention (1288) or high GI (1250). All 21 included studies reported the effect of low GI diets on risk factors for cardiovascular disease, including blood lipids and blood pressure.Twenty RCTs (18 of which were newly included in this version of the review) included primary prevention populations (healthy individuals or those at high risk of CVD, with mean age range from 19 to 69 years) and one RCT was in those diagnosed with pre-existing CVD (a secondary prevention population, with mean age 26.9 years). Most of the studies did not have an intervention duration of longer than six months. Difference in GI intake between comparison groups varied widely from 0.6 to 42.None of the included studies reported the effect of low GI dietary intake on cardiovascular mortality and cardiovascular events such as fatal and nonfatal myocardial infarction, unstable angina, coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty, and stroke. The unclear risk of bias of most of the included studies makes overall interpretation of the data difficult. Only two of the included studies (38 participants) reported on adverse effects and did not observe any harms (low-quality evidence).

AUTHORS' CONCLUSIONS

There is currently no evidence available regarding the effect of low GI diets on cardiovascular disease events. Moreover, there is currently no convincing evidence that low GI diets have a clear beneficial effect on blood lipids or blood pressure parameters.