OBJECTIVE: The aim of this systematic review was to investigate the effects of whole grain Avena sativa and Hordeum vulgare L., or their isolated fractions, on immune and inflammatory functions, as well as their influence on gut microbiota. A structured literature search was undertaken in line with PRISMA guidelines. Randomized controlled trials (RCTs) that investigated the effects of oats or barley consumption in adults and reported ≥ 1 of the following: C-reactive protein (CRP), tumor necrosis factor (TNF-α), interleukin-6 (IL-6), IL-2, IL-8, IL-18, lipopolysacharide binding protein (LBP) or gut microbiota-related outcomes, were included.
RESULTS: A total of 16 RCTs were included, among which 6 studies recruited metabolically at-risk population, including individuals with overweight and obesity, metabolic syndrome or hypercholesterolemia. Additionally, 3 trials involved young healthy population, 5 trials targeted older individuals (aged over 50 years), and 2 studies encompassed populations with other disease states. A total of 1091 individuals were included in the evaluation of short-term (up to 14 days) and long-term (beyond 14 days, up to 90 days) supplementation with oats or barley-based products. 9 studies measured inflammatory biomarkers and 5 of them reported significant reductions, specifically in long-term studies. Notably, no evidence of anti-inflammatory benefits was found in healthy individuals, whereas studies involving metabolically at-risk populations showed promising reductions in inflammation. 13 studies measured the impact on gut microbiota, and collectively suggest that oats and barley food products can influence the composition of gut microbiota, associated in some cases with metabolic improvements. Oats and barley consumption may confer anti-inflammatory effects in metabolically at-risk populations and influence gut microbiota outcomes. However, no anti-inflammatory benefits were observed in healthy individuals. Results from this systematic review suggests caution in interpreting findings due to limited trials and variations in interventions and health conditions.

Avena sativa L. (A. sativa L.), commonly known as oat, is a significant cereal grain crop with excellent edible and medicinal value. Oat polysaccharides (OPs), the major bioactive components of A. sativa L., have received considerable attention due to their beneficial bioactivities. However, the isolation and purification methods of OPs lack innovation, and the structure-activity relationship remains unexplored. This review emphatically summarized recent progress in the extraction and purification methods, structural characteristics, biological activities, structure-to-function associations and the potential application status of OPs. Different materials and isolation methods can result in the differences in the structure and bioactivity of OPs. OPs are mainly composed of various monosaccharide constituents, including glucose, arabinose and mannose, along with galactose, xylose and rhamnose in different molar ratios and types of glycosidic bonds. OPs exhibited a broad molecular weight distribution, ranging from 1.34 × 105 Da to 4.1 × 106 Da. Moreover, structure-activity relationships demonstrated that the monosaccharide composition, molecular weight, linkage types, and chemical modifications are closely related to their multiple bioactivities, including immunomodulatory activity, antioxidant effect, anti-inflammatory activity, antitumor effects etc. This work can provide comprehensive knowledge, update information and promising directions for future exploitation and application of OPs as therapeutic agents and multifunctional food additives.

Background: In recent years, oats\' effect on lowering serum cholesterol has been recognized. However, no systematic reviews summarized the effect of daily consumption of oat-based products on serum lipids in patients with dyslipidemia. Methods: We searched eight databases and two clinical trial registries from inception to July 31, 2023. We included randomized controlled trials (RCTs) evaluating the efficacy of oat-based products (≥4 weeks) on lipid levels or cardiovascular events in patients with dyslipidemia. Two authors independently screened articles, extracted data and assessed the risk of bias of included studies with Cochrane risk-of-bias tool 2.0. We used STATA 17.0 to conduct meta-analysis and Grading of Recommendations Assessment, Development and Evaluation (GRADE) to assess the certainty of evidence. Results: We finally included 17 eligible trials with 1731 subjects. The oat intervention varied from oat β-glucan-based products to oat bran-based products and wholegrain oat. Overall, the risk of bias of included trials was high or some concerns were noted because of the inadequate randomization, allocation concealment, and inappropriate data analysis method. Compared to the placebo or usual diet, one study indicated that oat-based products have no significant difference in major cardiovascular events. Pooled estimates showed that oat-based products may result in a large reduction in LDL-C (WMD, -0.24 mmol L-1; 95% CI: -0.33, -0.15) (moderate certainty) and TC (WMD, -0.32 mmol L-1; 95% CI: -0.48, -0.17) (moderate certainty). Compared to other diets (mainly other cereals), oat-based products probably reduce the level of LDL-C (WMD, -0.17 mmol L-1; 95% CI: -0.25, -0.08) (moderate certainty) and TC (WMD, -0.21 mmol L-1; 95% CI: -0.30, -0.12) (moderate certainty). Both groups showed that oat-based products had little effect on HDL-C and TG (moderate certainty). Oat-related adverse events were mostly gastrointestinal such as diarrhea, nausea, and flatulence being the most prevalent. Conclusions: Oat-based products may reduce TC and LDL-C, but have little effect on TG, HDL-C, and major cardiovascular events in patients with dyslipidemia.

Oats (Avena sativa L.) are one of the worldwide cereal crops. Avenanthramides (AVNs), the unique plant alkaloids of secondary metabolites found in oats, are nutritionally important for humans and animals. Numerous bioactivities of AVNs have been investigated and demonstrated in vivo and in vitro. Despite all these, researchers from all over the world are taking efforts to learn more knowledge about AVNs. In this work, we highlighted the recent updated findings that have increased our understanding of AVNs bioactivity, distribution, and especially the AVNs biosynthesis. Since the limits content of AVNs in oats strictly hinders the demand, understanding the mechanisms underlying AVN biosynthesis is important not only for developing a renewable, sustainable, and environmentally friendly source in both plants and microorganisms but also for designing effective strategies for enhancing their production via induction and metabolic engineering. Future directions for improving AVN production in native producers and heterologous systems for food and feed use are also discussed. This summary will provide a broad view of these specific natural products from oats.
• Avenanthramides are unique nutritional alkaloids in oats• AVN bioactivity, distribution, and the potential AVNs biosynthesis are discussed• AVNs can be produced via induction and metabolic engineering.

β-glucans are soluble fibers found in cereal compounds, including barley, oats etc., as an active component. They are used as a dietary fiber to treat cholesterol, diabetes and cardiovascular diseases. These polysaccharides are important because they can provide many therapeutic benefits related to their biological activity in human like inhibiting tumour growth, anti-inflammatory action, etc. All these activities were usually attached to their molecular weight, structure and degree of branching. The present manuscript reviews the background of β-glucan, its characterization techniques, the possible ways to extract β-glucan and mainly focuses on membrane-based purification techniques. The β-glucan separation methods using polymeric membranes, their operational characteristics, purification methods which may yield pure or crude β-glucan and structural analysis methods were also discussed. Future direction in research and development related to β-glucan recovery from cereal were also offered.

Oat (Avena sativa L.), an annual herbaceous plant belonging to the Gramineae family, is widely grown in various regions including EU, Canada, America, Australia, etc. Due to the nutritional and pharmacological values, oats have been developed into various functional food including fermented beverage, noodle, cookie, etc. Meanwhile, numerous studies have demonstrated that oats may effectively improve metabolic syndrome, such as dyslipidemia, hyperglycemia, atherosclerosis, hypertension, and obesity. However, the systematic pharmacological mechanisms of oats on metabolic syndrome have not been fully revealed. Therefore, in order to fully explore the benefits of oat in food industry and clinic, this review aims to provide up-to-date information on oat and its constituents, focusing on the effects on metabolic syndrome.

The gut microbiota consists of a set of microorganisms that colonizes the intestine and ferment fibers, among other nutrients, from the host\'s diet. A healthy gut microbiota, colonized mainly by beneficial microorganisms, has a positive effect on digestion and plays a role in disease prevention. However, dysregulation of the gut microbiota can contribute to various diseases. The nutrition of the host plays an important role in determining the composition of the gut microbiota. A healthy diet, rich in fiber, can beneficially modulate the gut microbiota. In this sense, oats are a source of both soluble and insoluble fiber. Oats are considered a functional ingredient with prebiotic potential and contain plant proteins, unsaturated fats, and antioxidant compounds. The impact of oat consumption on the gut microbiota is still emerging. Associations between oat consumption and the abundance of Akkermansia muciniphila, Roseburia, Lactobacillus, Bifidobacterium, and Faecalibacterium prausnitzii have already been observed. Therefore, this integrative review summarizes the findings from studies on the relationship between oat consumption, the gut microbiota, and the metabolites, mainly short-chain fatty acids, it produces.

Plant-based milk alternatives have become increasingly desirable due to their sustainability and the increased consumer awareness of health. Among many varieties of emerging plant-based milk, the smooth texture and flavor of oat milk make it spread rapidly around the world. Furthermore, as a sustainable source of diet, oats can provide rich nutrients and phytochemicals. Issues on the stability, sensory properties, shelf life, and nutritional quality of oat milk have been highlighted in published studies. In this review, the processing techniques, quality improvement, and product features of oat milk are elaborated, and the potential applications of oat milk are summarized. Besides, the challenges and future perspectives of oat milk production in the future are discussed.

This study aims to review the hunger hormones in obesity management and the impact of oats in regulating these hormones for hunger suppression and body weight management. In this review, the impact of various edible forms of oats like whole, naked, sprouted, or supplemented has been investigated for their appetite hormones regulation and weight management.
The onset of obesity has been greatly associated with the appetite-regulating hormones that control, regulate, and suppress hunger, satiety, or energy expenditure. Many observational and clinical studies prove that oats have a positive effect on anthropometric measures like BMI, waist circumference, waist-to-hip ratio, lipid profile, total cholesterol, weight, appetite, and blood pressure. Many studies support the concept that oats are rich in protein, fiber, healthy fats, Fe, Zn, Mg, Mn, free phenolics, ß-glucan, ferulic acid, avenanthramides, and many more. Beta-glucan is the most important bioactive component that lowers cholesterol levels and supports the defense system of the body to prevent infections. Hence, several clinical studies supported oats utilization against obesity, appetite hormones, and energy regulation but still, some studies have shown no or little significance on appetite. Results of various studies revealed the therapeutic potentials of oats for body weight management, appetite control, strengthening the immune system, lowering serum cholesterol, and gut microbiota promotion by increased production of short-chain fatty acids.

It is well known that dietary fiber positively impacts the microbiome and health as a whole. However, the health effects of β-glucan, a dietary fiber extracted from oats, have been questioned when administered alone or incorporated into other foods. The purpose of this systematic review and meta-analysis was to evaluate the impact of oats or β-glucan supplements on the lipid profile.
Randomized controlled trials with parallel-arm or crossover blinded interventions at least two weeks in duration, for hyperlipidemic or non-hyperlipidemic men and women ≥18 years of age were selected. Only single (participants blinded) or double-blinded studies that compared oat or isolated β-glucan with a placebo/control group were considered for this review. The databases EMBASE, PubMed, Web of science and CINHAL were searched, from the earliest indexed year available online to the end of January 2022. Random-effects models were used to combine the estimated effects extracted from individual studies, and data were summarized as standardized mean difference (SMD) and 95% confidence interval (95%CI).
A total of 811 articles were screened for eligibility, and relevant data were extracted from 28 studies, totaling 1494 subjects. Oat interventions TC (-0.61, 95%CI: -0.84;-0.39, p < 0.00001, and -0.70, 95%CI: -1.07;-0.34, p = 0.0002, respectively) and LDL (-0.51, 95%CI: -0.71;-0.31, p < 0.00001, and -0.38, 95%CI: -0.60;-0.15, p = 0.001, respectively). Moreover, isolated β-glucan interventions from parallel-arm studies decreased TC (-0.73, 95%CI: -1.01;-0.45, p < 0.00001), LDL (-0.58, 95%CI: -0.85;-0.32, p < 0.0001) and triglycerides (-0.30, 95%CI: -0.49;-0.12, p = 0.001). HDL was not altered by either oat or isolated β-glucan (p > 0.05).
Overall, this review showed that both oat and isolated β-glucan interventions improved lipid profiles. Furthermore, the ingestion of oats or isolated β-glucan supplements are effective tools to combat dyslipidemia and should be considered in cardiovascular disease prevention.