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

Efficacy of oats in dyslipidemia: a systematic review and meta-analysis

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.

Enhanced Elderberry Snack Bars: A Sensory, Nutritional, and Rheological Evaluation

Interest in functional foods is continuously increasing, having the potential to be an ally in reducing cardiometabolic risk factors. This study focuses on developing and evaluating oat- and millet-based snack bars enriched with freeze-dried elderberry powder (FDEBP), aiming to combine great taste with enhanced nutritional value, antioxidant properties, and prebiotic potential. The research encompassed a sensory evaluation, nutritional assessment, and rheological analysis of the snack bars. A hedonic test was conducted to gauge consumer preferences and overall liking, providing insights into taste, texture, and acceptance. Sensory evaluation revealed positive feedback from participants, and acceptance rating scores ranged from 7 to 8.04, the best score recorded by one of the enhanced bars with 1% FDEBP. The rheological analysis determined the bars' dynamic storage modulus (G') and loss modulus (G″), assessing the material's elasticity and mechanical properties. Results showed that the incorporation of 0.5% and 1% FDEBP in the oat and millet snack bars significantly impacted their rheological properties, enhancing structural strength. Nutritional analysis demonstrated that the snack bars provided a complete mix of macronutrients required in a daily diet. The study sheds light on the potential of functional snack bars enriched with FDEBP, offering a delectable way to access essential nutrients and bioactive compounds in a minimally processed form, without the addition of sweeteners or additives, friendly to the gut microbiota.

The Effect of Dietary Oat Consumption and Its Constituents on Fat Storage and Obesity

This review is to summarize and analyze the currently available knowledge concerning the action of oat (Avena sativa L.) consumption on obesity, as well as possible constituents and extra- and intracellular mediators responsible for its anti-obesity effect. The oat constituents could reduce fat storage via several mediatory mechanisms - brain centers regulating appetite, gastrointestinal functions, gut bacteria, fat synthesis and metabolism and maybe via changes in oxidative processes, steroid hormones receptors and adipose tissue vascularization. Several oat constituents (starch, fiber and beta-glucan) could have anti-obesity properties, whilst one oat constituent (starch or fiber) could affect fat storage via several mechanisms of action.

Oat Beta-Glucan Alone and in Combination with Hydrochlorothiazide Lowers High Blood Pressure in Male but Not Female Spontaneously Hypertensive Rats

Oats are considered a functional food due to the beneficial health effects associated with their consumption and are suitable to be explored for their ability to prevent or manage chronic disease, such as hypertension. Here, we examined the cardiovascular benefits of an oat beta-glucan extract in male and female spontaneously hypertensive rats (SHRs) to unravel its sex-specific roles when used with an anti-hypertensive medication, hydrochlorothiazide. Five-week-old male and female SHRs and Wistar-Kyoto (WKY) rats were treated with oat beta-glucan and hydrochlorothiazide for 15 weeks. Twenty-week-old male and female SHRs showed high blood pressure (BP), cardiac remodeling, and cardiac dysfunction. These animals also had significantly increased levels of malondialdehyde (MDA), angiotensin II, and norepinephrine. Treatments with beta-glucan and hydrochlorothiazide were able to differentially prevent high BP, cardiac dysfunction, and alterations in malondialdehyde (MDA), angiotensin II, and norepinephrine in 20-week-old male and female SHRs. To conclude, beta-glucan alone and in combination with hydrochlorothiazide may be a promising a strategy for managing hypertension and related cardiac complications.

Effect of Oat (Avena sativa L.) Consumption on Lipid Profile With Focus on Triglycerides and High-density Lipoprotein Cholesterol (HDL-C): An Updated Systematic Review

Hypercholesterolemia is a significant risk factor for heart disease. The soluble fiber in oat (Avena sativa L.), beta-glucan has been shown to significantly lower serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels but not triglycerides (TG) and high-density lipoprotein cholesterol (HDL-C) according to previous studies, reviews, and meta-analyses. However, the effect of oat consumption on the TG and HDL-C is controversial and has not been expanded enough. We did this review study to find out about the effect of oat on lipid profile especially TG and HDL-C more specifically and meticulously with their details. After searching PubMed, Web of Science, and Google scholar we included 17 studies in our review. Our results similar to other reviews showed that oat reduced the TC, VLDL, and LDL-C more significantly than TG. Of 17 included studies 6 studies reported reduction of TG level, and only 1 study reported HDL-C improvement followed by oat consumption. A more detailed review of studies that reported positive effects of oat/ beta-glucan consumption on TG showed that in healthy people with normal lipid profile oat intake might reduce TG effectively and also in overweight people/those with diabetes or metabolic syndrome if a higher amount of oat or/and longer duration applied. Consuming oat in conjunction with calorie-reducing diets or using it with DHA can cause a significant TG reduction. It may be concluded that, in addition to lowering TC and LDL-C, a considerable improvement in TG or HDL-C can be accomplished by adjusting factors such as oat consumption dose or consumption duration or utilizing oat in conjunction with a proper diet program. To conclude, more research on this topic is required.

The Effect of Chia Seeds on High-Density Lipoprotein (HDL) Cholesterol

CONTEXT

Chia seeds are touted as a healthy food capable of providing a beneficial effect on high-density lipoprotein (HDL) cholesterol. Similar claims have been made for oats in various forms, claiming that they improve cholesterol or are in some way "heart healthy."

OBJECTIVE

 This study aims to demonstrate the effect of daily consumption of chia seeds, if any, on HDL cholesterol levels and compare this to the effects of oats on HDL levels.

METHODS

 This pilot study is a randomized controlled trial performed at an academic primary care center. Participation was voluntary, and all participants provided written consent prior to enrollment. There were no exclusion criteria other than that participants must be adults and willing to come in to get their cholesterol profiles checked at the beginning and end of the study. The participants consumed their assigned breakfast in a standard serving size for a month with blood draws and weights recorded before and after the diet. The patients' cholesterol profiles were also compared with their weights. To standardize the delivery of chia seeds, the group consuming chia seeds mixed them with oatmeal. The three meal groups consisted of Cheerios (red group), oatmeal (white group), and oatmeal with chia seeds (blue group). Initially, there were a total of 11 subjects, three in the red group, four in the white group, and four in the blue group. Two subjects were lost to follow-up, one each from the red and white groups. Statistical analysis including one-way analysis was done with the means, Wilcoxon/Kruskal-Wallis, and one-way analysis tests.

RESULTS

 The results showed a similar weight gain pattern between the three groups, with an average of 2.8 lbs gained in the red group, 2.4 lbs gained in the white group, and 2.6 lbs gained in the blue group. The average HDL levels decreased by 1.00 mg/dL in the red group (standard deviation (SD) 2.82843), increased by 2.00 mg/dL in the white group (SD 8.88819), and increased by 5.75 mg/dL in the blue group (SD 8.01561). The HDL:total cholesterol ratios decreased by 0.00748 in the red group (SD 0.002660), an average of 0.04053 in the white group (SD 0.028138), and an average of 0.01614 in the blue group (SD 0.023808).

CONCLUSION

 The results suggest that both chia seeds and oatmeal may be good dietary sources to naturally increase HDL cholesterol, more substantially so with the diet including chia seeds, but may or may not improve total cholesterol:HDL ratios. The effect of weight gain is unclear, as all groups gained weight similarly. Hence, further study is warranted.

The Adapted POM Analysis of Avenanthramides In Silico

POM analysis and related approaches are significant tools based on calculating various physico-chemical properties and predicting biological activity, ADME parameters, and toxicity of a molecule. These methods are used to evaluate a molecule's potential to become a drug candidate. Avenanthramides (AVNs) are promising secondary metabolites specific to Avena spp. (oat). They comprise the amides of anthranilic acid linked to various polyphenolic acids with or without post-condensation molecule transformation. These natural compounds have been reported to exert numerous biological effects, including antioxidant, anti-inflammatory, hepatoprotective, antiatherogenic, and antiproliferative properties. To date, almost 50 various AVNs have been identified. We performed a modified POM analysis of 42 AVNs using MOLINSPIRATION, SWISSADME, and OSIRIS software. The evaluation of primary in silico parameters revealed significant differences among individual AVNs, highlighting the most promising candidates. These preliminary results may help coordinate and initiate other research projects focused on particular AVNs, especially those with predicted bioactivity, low toxicity, optimal ADME parameters, and promising perspectives.

Dietary Supplements Containing Oat Beta-Glucan and/or Green Coffee (Poly)phenols Showed Limited Effect in Modulating Cardiometabolic Risk Biomarkers in Overweight/Obese Patients without a Lifestyle Intervention

Obesity has reached pandemic proportions and has become a major health concern worldwide. Therefore, it is necessary to find new strategies against this condition and its associated comorbidities. Green coffee polyphenols (GCP) and oat beta-glucans (BGs) have proven their hypolipidaemic and hypoglycaemic effects. This study aimed to examine the effects of the long-term consumption of supplements containing GCP, BG or the novel GCP/BG combination on lipid and glucose metabolism biomarkers in overweight/obese subjects who maintained their dietary habits and physical activity, hence addressing the difficulty that this population faces in adapting to lifestyle changes. A randomised, crossover, blind trial was carried out in 29 volunteers who consumed either GCP (300 mg), BG (2.5 g) or GCP/BG (300 mg + 2.5 g) twice a day for 8 weeks. Blood samples were collected, and blood pressure and body composition were measured at the beginning and end of each intervention. Total cholesterol, triglycerides, high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C), very low-density lipoprotein (VLDL-C) cholesterol, glycated haemoglobin, fasting glucose, insulin, aspartate transaminase, alanine transaminase and different hormones and adipokines were analysed. Only VLDL-C (p = 0.01) and diastolic blood pressure (p = 0.027) decreased after the intervention, especially with the BG supplement. There were no other significant changes in the analysed biomarkers. In conclusion, the regular intake of GCP, BG and GCP/BG without lifestyle changes is not an efficient strategy to improve lipid and glucose homeostasis in overweight/obese subjects.

The separate effects of whole oats and isolated beta-glucan on lipid profile: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND & AIMS

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.

METHODS

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).

RESULTS

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).

CONCLUSION

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.

Narrative Review on the Effects of Oat and Sprouted Oat Components on Blood Pressure

Hypertension (HTN) is a major risk factor for cardiovascular disease (CVD) and cognitive decline. Elevations in blood pressure (BP) leading to HTN can be found in young adults with increased prevalence as people age. Oats are known to decrease CVD risk via an established effect of β-glucan on the attenuation of blood cholesterol. Many past studies on CVD and oats have also reported a decrease in BP; however, a thorough assessment of oats and BP has not been conducted. Moreover, oats deliver several beneficial dietary components with putative beneficial effects on BP or endothelial function, such as β-glucan, γ-amino butyric acid (GABA), and phytochemicals such as avenanthramides. We conducted a comprehensive search for systematic reviews, meta-analyses, and clinical intervention studies on oats and BP and identified 18 randomized controlled trials (RCTs) and three meta-analyses that supported the role of oats in decreasing BP. Emerging data also suggest oat consumption may reduce the use of anti-hypertensive medications. The majority of these studies utilized whole oats or oat bran, which include a vast array of oat bioactives. Therefore, we also extensively reviewed the literature on these bioactives and their putative effect on BP-relevant mechanisms. The data suggest several oat components, such as GABA, as well as the delivery of high-quality plant protein and fermentable prebiotic fiber, may contribute to the anti-HTN effect of oats. In particular, GABA is enhanced in oat sprouts, which suggests this food may be particularly beneficial for healthy BP management.

Efficacy of oats for dyslipidaemia: protocol for a systematic review and meta-analysis

INTRODUCTION

Dyslipidaemia is a critical factor in the development of atherosclerotic cardiovascular disease. Concerning dyslipidaemia regulation, we advocate for lifestyle interventions such as diet to complement drug treatment. Numerous studies have confirmed that oat β-glucan, a critical component of oats, can help lower cholesterol. However, there is no conclusive evidence for the efficacy of oats and their products in the treatment of dyslipidaemia. As a result, we have developed this protocol to serve as a guide for future research on oat intervention for dyslipidaemias.

METHODS AND ANALYSIS

We will conduct a search of eight databases or websites (PubMed, Web of Science, Cochrane Library, EMBASE, CNKI, SinoMed, VIP and Wanfang) to identify studies on oats' ability to regulate blood lipid levels. Two authors will screen articles independently, extract data based on inclusion and exclusion criteria, and assess the quality and bias of included studies. To assess and quantify heterogeneity, Q and I² statistics will be used. If there is significant heterogeneity between studies, the source of the heterogeneity will be investigated using subgroup analysis and sensitivity analysis. We will analyse potential publication bias using the Begg funnel plot and Egger's weighted regression statistics. To assess the quality of evidence for the primary outcomes, the Grades of Recommendations, Assessment, Development and Evaluation method will be used.

ETHICS AND DISSEMINATION

This study is based on the existing literature and data in the databases. It is not subject to ethical review. The findings, on the other hand, will be published in a peer-reviewed journal. These findings may aid in the management of dyslipidaemia on a daily basis.

PROSPERO REGISTRATION NUMBER

CRD42021226751.