Changes in serum cholesterol and sterol metabolites after intake of products enriched with an oat bran concentrate within a controlled diet

Effects of cereal bran consumption on cardiometabolic risk factors: A systematic review and meta-analysis

AIMS

Cardiovascular disease is a prevalent worldwide disease, and cardiometabolic risk factors (CMRFs) include hyperlipidemia, hypertension, diabetes, and adiposity. Healthy diets are the critical factor in controlling these CMRFs risks, especially cereal bran which contains many beneficial substances. However, there are still contradictions in the indicators of improving CMRFs by bran from different grain sources or even the same grain source. Therefore, this study aimed to investigate the effects of cereal bran consumption on CMRFs.

DATA SYNTHESIS

Eligible randomized controlled studies were searched in PubMed, Embase, Scopus, the Cochrane Library and Web of Science until February 2023. The random-effects model was used to calculate overall effect sizes of weighted mean difference (WMD) and 95% confidence interval (CI). Finally, 22 studies were included in the present meta-analysis. Compared to the control, cereal bran consumption had no significant effect on high-density lipoprotein cholesterol, triglycerides, waist circumference, and body mass index, but could reduce systolic blood pressure (WMD: -1.59; 95% CI: -2.45 to -0.72), diastolic blood pressure (WMD: -1.96; 95% CI: -3.89 to -0.04), total cholesterol (WMD: -0.19; 95% CI: -0.34 to -0.04), low-density lipoprotein cholesterol (WMD: -0.21; 95% CI: -0.38 to -0.04), and fasting blood glucose (WMD: -0.13; 95% CI: -0.24 to -0.01). Additionally, oat bran can lower blood lipids in individuals with lipid diseases and blood pressure in obese or hypertensive patients.

CONCLUSIONS

Cereal bran could significantly reduce blood pressure, total cholesterol, low-density lipoprotein cholesterol, and fasting blood glucose in individuals with CMRFs, and oat bran had the most obvious effect.

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.

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.

Biochemical assessment of oat genotypes revealed variability in grain quality with nutrition and crop improvement implications

Oat is a potent source of nutrients and bioactive compounds offering potential health benefits and role in combating micronutrient malnutrition problems. To exploit nutritional and quality traits of oats, a biochemical assessment of 112 oat genotypes was conducted. The high range of variability for total phenol (1.7-31.3 mg/g), β-glucan (1.0-8.0 mg/g), calcium (1.91-4.34 mg/g), zinc (3.80-6.50 mg/100 g), iron (0.66-4.89 mg/100 g) and manganese (2.88-8.0 mg/100 g) was revealed among genotypes. A higher amount of iron and zinc was found in genotypes OS-6, HFO-638, HFO-915 & HFO-918, whereas, elevated levels of manganese and zinc were recorded in genotypes OS-403 & OL-1804. The results revealed groups of low phytic acid oat genotypes containing high crude protein (HFO-52, HFO-270, HFO-330), β-glucan (HFO-62, HFO-588, HFO-926). A significant positive correlation was obtained between copper with iron, manganese, and calcium content. These findings could be useful for developing value-added oat food products and novel oat varieties.

Effects of Oat Beta-Glucan Intake on Lipid Profiles in Hypercholesterolemic Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

(1) Background: hyperlipidemia is one of the cardiovascular diseases which becomes a great threat to the health of people worldwide. Oat beta-glucan is reported to have a beneficial effect on lowering blood lipids. To probe the effect of oat beta-glucan consumption on serum lipid profiles (total cholesterol, total triglyceride, high-density lipoprotein-cholesterol, and low-density lipoprotein-cholesterol), we carried out a systematic search on randomized controlled trials of oat beta-glucan intervention on hypercholesterolemic individuals. (2) Methods: the pieces of literature were obtained from PubMed, Scopus, Cochrane Library, Web of Science, and the Embase from inception to 28 February 2022. The results were presented with the weighted mean difference (WMD) with a 95% CI. The random-effects or fixed-effects model was applied according to the heterogeneity. The subgroup analysis and meta-regression were used to identify the source of heterogeneity. (3) Results: thirteen trials with 927 participants were included in our meta-analysis. Overall, oat beta-glucan supplementation significantly reduced levels of TC (pooled WMD = −0.24 mmol/L; 95%CI: −0.28 to −0.20 mmol/L), LDL-c (pooled WMD = −0.27 mmol/L; 95%CI: −0.35 to −0.20 mmol/L). Furthermore, beta-glucan consumption did not show significant effects on TG (pooled WMD = −0.04 mmol/L; 95%CI: −0.13 to 0.05 mmol/L), HDL-c (pooled WMD = 0.00 mmol/L; 95%CI: −0.05 to 0.05 mmol/L). Subgroup analysis indicated that critical factors, such as disease severity of participants, the daily intervention of oat beta-glucan, source of oat beta-glucan, and duration of intervention had impacts on outcomes. (4) Conclusions: oat beta-glucan intake may significantly decrease the level of TC and LDL-c while no significant changes in TG and HDL-c were observed. This meta-analysis supports the health benefits of oat beta-glucan, especially for its cholesterol-lowering features, although it has some inevitable limitations.

Effects of different delivering matrices of β-glucan on lipids in mildly hypercholesterolaemic individuals: a meta-analysis of randomised controlled trials

β-Glucan has been reported for its health benefits on blood lipids in hypercholesterolaemic individuals for years. However, people have paid little attention to the effects of β-glucan in populations with mild hypercholesterolaemia as well as the various delivering matrices. Our objective was to perform a meta-analysis to analyse the effects of β-glucan with different delivering matrices in mildly hypercholesterolaemic individuals. After conducting a comprehensive search in Web of Science, PubMed, Scopus and Cochrane Library, a total of twenty-one randomised controlled trials involving 1120 participants were identified to measure the pooled effect. The overall results indicated that consuming a dose of ≥3 g/d of β-glucan for at least 3 weeks could significantly reduce total cholesterol (TC) (−0·27 mmol/l, 95 % CI −0·33, −0·21, P < 0·001) and LDL-cholesterol (−0·26 mmol/l, 95% CI −0·32, −0·20, P < 0·001) compared with the control group in mildly hypercholesterolaemic individuals, while no significant difference was observed in TAG (−0·03 mmol/l, 95% CI −0·11, 0·06, P = 0·521) and HDL-cholesterol (0·01 mmol/l, 95% CI −0·03, 0·04, P = 0·777). There was evidence for modest unexplained heterogeneity in the meta-analysis. In conclusion, β-glucan can significantly reduce risk factors like TC and LDL-cholesterol for CVD in mildly hypercholesterolaemic individuals; furthermore, it appears that the effects of food matrices with both ‘solid products’ and ‘liquid products’ where β-glucan was incorporated into were ranked as the best way to exert its beneficial properties, while ‘liquid’ and ‘solid’ products were ranked as the second and third positions, respectively.

Processing of oat: the impact on oat's cholesterol lowering effect

Epidemiological and interventional studies have clearly demonstrated the beneficial impact of consuming oat and oat-based products on serum cholesterol and other markers of cardiovascular disease. The cholesterol-lowering effect of oat is thought to be associated with the β-glucan it contains. However, not all food products containing β-glucan seem to lead to the same health outcome. Overall, highly processed β-glucan sources (where the oat tissue is highly disrupted) appear to be less effective at reducing serum cholesterol, but the reasons are not well understood. Therefore, the mechanisms involved still need further clarification. The purpose of this paper is to review current evidence of the cholesterol-lowering effect of oat in the context of the structure and complexity of the oat matrix. The possibility of a synergistic action and interaction between the oat constituents promoting hypocholesterolaemia is also discussed. A review of the literature suggested that for a similar dose of β-glucan, (1) liquid oat-based foods seem to give more consistent, but moderate reductions in cholesterol than semi-solid or solid foods where the results are more variable; (2) the quantity of β-glucan and the molecular weight at expected consumption levels (∼3 g day-1) play a role in cholesterol reduction; and (3) unrefined β-glucan-rich oat-based foods (where some of the plant tissue remains intact) often appear more efficient at lowering cholesterol than purified β-glucan added as an ingredient.

The effect of oat β-glucan on LDL-cholesterol, non-HDL-cholesterol and apoB for CVD risk reduction: a systematic review and meta-analysis of randomised-controlled trials

Oats are a rich source of β-glucan, a viscous, soluble fibre recognised for its cholesterol-lowering properties, and are associated with reduced risk of CVD. Our objective was to conduct a systematic review and meta-analysis of randomised-controlled trials (RCT) investigating the cholesterol-lowering potential of oat β-glucan on LDL-cholesterol, non-HDL-cholesterol and apoB for the risk reduction of CVD. MEDLINE, Embase, CINAHL and Cochrane CENTRAL were searched. We included RCT of ≥3 weeks of follow-up, assessing the effect of diets enriched with oat β-glucan compared with controlled diets on LDL-cholesterol, non-HDL-cholesterol or apoB. Two independent reviewers extracted data and assessed study quality and risk of bias. Data were pooled using the generic inverse-variance method with random effects models and expressed as mean differences with 95 % CI. Heterogeneity was assessed by the Cochran's Q statistic and quantified by the I 2-statistic. In total, fifty-eight trials (n 3974) were included. A median dose of 3·5 g/d of oat β-glucan significantly lowered LDL-cholesterol (-0·19; 95 % CI -0·23, -0·14 mmol/l, P<0·00001), non-HDL-cholesterol (-0·20; 95 % CI -0·26, -0·15 mmol/l, P<0·00001) and apoB (-0·03; 95 % CI -0·05, -0·02 g/l, P<0·0001) compared with control interventions. There was evidence for considerable unexplained heterogeneity in the analysis of LDL-cholesterol (I 2=79 %) and non-HDL-cholesterol (I 2=99 %). Pooled analyses showed that oat β-glucan has a lowering effect on LDL-cholesterol, non-HDL-cholesterol and apoB. Inclusion of oat-containing foods may be a strategy for achieving targets in CVD reduction.

Nutritional advantages of oats and opportunities for its processing as value added foods - a review

Oats (Avena sativa L.) have received considerable attention for their high content of dietary fibres, phytochemicals and nutritional value. It is believed that consumption of oats possesses various health benefits such as hypocholesterolaemic and anticancerous properties. Oats have also recently been considered suitable in the diet of celiac patients. Owing to their high nutritional value, oat-based food products like breads, biscuits, cookies, probiotic drinks, breakfast cereals, flakes and infant food are gaining increasing consideration. Research and development on oat and its products may be helpful in combating various diseases known to mankind. This paper provides an overview of the nutritional and health benefits provided by oats as whole grains and its value added products. It is designed to provide an insight on the processing of oats and its effect on their functional properties. The manuscript also reviews various uses of oats and its fractions for clinical and industrial purposes and in development of value added food products.

Cholesterol-lowering effects of oat β-glucan: a meta-analysis of randomized controlled trials

BACKGROUND

Health claims regarding the cholesterol-lowering effect of soluble fiber from oat products, approved by food standards agencies worldwide, are based on a diet containing ≥3 g/d of oat β-glucan (OBG). Given the number of recently published randomized controlled trials (RCTs), it is important to update the findings of previous meta-analyses.

OBJECTIVE

The objective was to quantify the effect of ≥3 g OBG/d on serum cholesterol concentrations in humans and investigate potential effect modifiers.

DESIGN

A meta-analysis was performed on 28 RCTs comparing ≥3 g OBG/d with an appropriate control. Systematic searches were undertaken in PubMed, AGRICOLA, and Scopus between 1 January 1966 and 6 June 2013, plus in-house study reports at CreaNutrition AG. Studies were assessed with regard to inclusion/exclusion criteria, and data were extracted from included studies by reviewers working independently in pairs, reconciling differences by consensus. Estimates of the mean reduction in serum cholesterol from baseline between the OBG and control diets were analyzed by using random-effects meta-analysis models and meta-regression.

RESULTS

OBG in doses of ≥3 g/d reduced low-density lipoprotein (LDL) and total cholesterol relative to control by 0.25 mmol/L (95% CI: 0.20, 0.30; P < 0.0001) and 0.30 mmol/L (95% CI: 0.24, 0.35; P < 0.0001), respectively, with some indication of heterogeneity (P = 0.13 and P = 0.067). There was no significant effect of OBG on high-density lipoprotein (HDL) cholesterol or triglycerides and no evidence that dose (range across trials: 3.0-12.4 g/d) or duration of treatment (range: 2-12 wk) influenced the results. LDL cholesterol lowering was significantly greater with higher baseline LDL cholesterol. There was a significantly greater effect for both LDL and total cholesterol in subjects with diabetes compared with those without (although based on few studies).

CONCLUSIONS

Adding ≥3 g OBG/d to the diet reduces LDL and total cholesterol by 0.25 mmol/L and 0.30 mmol/L, respectively, without changing HDL cholesterol or triglycerides.

A high intake of dietary fiber influences C-reactive protein and fibrinogen, but not glucose and lipid metabolism, in mildly hypercholesterolemic subjects

PURPOSE

The aim of the study was to investigate how a diet high in dietary fiber, with several fiber sources included, modulates glucose and lipid metabolism and the inflammatory response in humans.

METHODS

Subjects (n = 25) aged 58.6 (1.1) years (mean and SD) with a BMI of 26.6 (0.5) kg/m(2) and a total cholesterol (TC) of 5.8 (0.1) mmol/L (mean and SEM) were given a high fiber (HF) and low fiber (LF) diet, in a randomized controlled 5-week crossover intervention, separated by a 3-week washout. The HF diet consisted of oat bran, rye bran, and sugar beet fiber incorporated into test food products; one bread roll, one ready meal, and two beverages consumed daily. Equivalent food products, without added fibers, were provided in the LF diet.

RESULTS

Total dietary fiber intake was 48.0 g and 30.2 g per day for the HF and LF diet, respectively. Significant reduction in C-reactive protein (CRP) was observed between the diets (P = 0.017) and a significant reduction in fibrinogen within the HF diet (P = 0.044). There were no significant effects in other measured circulating cytokines or in glucose, insulin, and lipid levels.

CONCLUSIONS

Our study suggests that a 5-week high dietary fiber intake of oat bran, rye bran, and sugar beet fiber might reduce the low-grade inflammatory response measured as CRP which could, together with reduced fibrinogen, help to prevent the risk of cardiovascular disease.

Physicochemical properties of oat β-glucan influence its ability to reduce serum LDL cholesterol in humans: a randomized clinical trial

BACKGROUND

Consumption of 3 g oat β-glucan/d is considered sufficient to lower serum LDL cholesterol, but some studies have shown no effect. LDL cholesterol lowering by oat β-glucan may depend on viscosity, which is controlled by the molecular weight (MW) and amount of oat β-glucan solubilized in the intestine (C).

OBJECTIVES

Our 2 primary objectives were to determine whether consumption of 3 g high-MW oat β-glucan/d would reduce LDL cholesterol and whether LDL cholesterol lowering was related to the log(MW × C) of oat β-glucan.

DESIGN

In a double-blind, parallel-design, multicenter clinical trial, subjects with LDL cholesterol ≥3.0 and ≤5.0 mmol/L (n = 786 screened, n = 400 ineligible, n = 19 refused, n = 367 enrolled, and n = 345 completed) were randomly assigned to receive cereal containing wheat fiber (n = 87) or 3 g high-MW (2,210,000 g/mol, n = 86), 4 g medium-MW (850,000 g/mol, n = 67), 3 g medium-MW (530,000 g/mol, n = 64), or 4 g low-MW (210,000 g/mol, n = 63) oat β-glucan/d (divided doses, twice daily) for 4 wk.

RESULTS

LDL cholesterol was significantly less with 3 g high-MW, 4 g medium-MW, and 3 g medium-MW oat β-glucan cereals than with the wheat-fiber cereal by 0.21 (5.5%; 95% CI: -0.11, -0.30; P = 0.002), 0.26 (6.5%; 95% CI: -0.14, -0.37; P = 0.0007), and 0.19 (4.7%; 95% CI: -0.08, -0.30; P = 0.01) mmol/L, respectively. However, the effect of 4 g low-MW oat β-glucan/d (0.10 mmol/L) was not significant (2.3%; 95% CI: 0.02, -0.20). By analysis of covariance, log(MW × C) was a significant determinant of LDL cholesterol (P = 0.003). Treatment effects were not significantly influenced by age, sex, study center, or baseline LDL cholesterol.

CONCLUSIONS

The physicochemical properties of oat β-glucan should be considered when assessing the cholesterol-lowering ability of oat-containing products; an extruded breakfast cereal containing 3 g oat β-glucan/d with a high-MW (2,210,000 g/mol) or a medium-MW (530,000 g/mol) lowered LDL cholesterol similarly by ≈0.2 mmol/L (5%), but efficacy was reduced by 50% when MW was reduced to 210,000 g/mol. This trial was registered at www.clinicaltrials.gov as NCT00981981.

Processing affects the physicochemical properties of beta-glucan in oat bran cereal

The tendency of mixed linkage oat beta-glucan to form viscous solutions is generally assumed to be related to its ability to lower serum cholesterol levels in humans. However, the association has not been clearly demonstrated. To conduct a clinical trial showing the relationship between LDL-cholesterol levels and viscosity, a series of extruded oat bran cereals were prepared in which the beta-glucan had a range of molecular weights and modified solubility. An extraction protocol using physiological enzymes at 37 degrees C was used to estimate the effect that the cereals would have on gut viscosity. By reducing the molecular weight from 1,930,000 to 251,000 g/mol, the apparent viscosity in the physiological extract dropped from 2900 to 131 mPa.s (at 30 s(-1)). Microscopic examination showed that as the extrusion conditions were made more severe, to cause depolymerization, the integrity of the cell walls was lost and beta-glucan dispersed throughout the cereal. Differences in the hardness and density of the extruded cereals were also evident as the molecular weight was reduced.

Functional foods for dyslipidaemia and cardiovascular risk prevention

A food can be regarded as ‘functional’ if it can demonstrate a beneficial efficacy on one or more target functions in the body in a convincing way. Beyond adequate nutritional qualities, functional foods should either improve the state of health and wellbeing and/or reduce the risk of disease. Functional foods that are marketed with claims of heart disease reduction focus primarily on the major risk factors, i.e. cholesterol, diabetes and hypertension. Some of the most innovative products are designed to be enriched with ‘protective’ ingredients, believed to reduce risk. They may contain, for example, soluble fibre (from oat and psyllium), useful both for lowering cholesterol and blood pressure, or fructans, effective in diabetes. Phytosterols and stanols lower LDL-cholesterol in a dose-dependent manner. Soya protein is more hypocholesterolaemic in subjects with very high initial cholesterol and recent data indicate also favourable activities in the metabolic syndrome.n-3 Fatty acids appear to exert significant hypotriacylglycerolaemic effects, possibly partly responsible for their preventive activity. Dark chocolate is gaining much attention for its multifunctional activities, useful both for the prevention of dyslipidaemia as well as hypertension. Finally, consensus opinions about tea and coffee have not emerged yet, and the benefits of vitamin E, garlic, fenugreek and policosanols in the management of dyslipidaemia and prevention of arterial disease are still controversial.

Changes in serum lipids and postprandial glucose and insulin concentrations after consumption of beverages with beta-glucans from oats or barley: a randomised dose-controlled trial

OBJECTIVES

To investigate side by side the effects on serum lipoproteins and postprandial glucose and insulin concentrations of beverages enriched with 5 or 10 g of beta-glucans from oats or barley.

DESIGN AND SETTING

An 8-week single blind, controlled study with five parallel groups carried out at two centres under identical conditions.

SUBJECTS

A total of 100 free-living hypercholesterolaemic subjects were recruited locally and 89 completed the study.

INTERVENTIONS

During a 3-week run-in period all subjects consumed a control beverage. For the following 5-week period four groups received a beverage with 5 or 10 g beta-glucans from oats or barley and one group continued with the control beverage. Blood samples in weeks 0, 2, 3, 7 and 8 were analysed for serum lipids, lipoproteins, glucose and insulin. Postprandial concentrations of glucose and insulin were compared between control and the beverage with 5 g of beta-glucans from oats or barley.

RESULTS

Compared to control, 5 g of beta-glucans from oats significantly lowered total-cholesterol by 7.4% (P<0.01), and postprandial concentrations of glucose (30 min, P=0.005) and insulin (30 min, P=0.025). The beverage with 10 g of beta-glucans from oats did not affect serum lipids significantly in comparison with control. No statistically significant effects compared to control of the beverages with barley beta-glucans were found.

CONCLUSIONS

A daily consumption of 5 g of oat beta-glucans in a beverage improved the lipid and glucose metabolism, while barley beta-glucans did not.

Yeast-leavened oat breads with high or low molecular weight beta-glucan do not differ in their effects on blood concentrations of lipids, insulin, or glucose in humans

Increased intestinal viscosity appears to be the major mode of action by which dietary oat beta-glucan increases the fecal excretion of bile acids and thereby lowers blood cholesterol concentrations. The objective of this experiment was to investigate whether there is a difference in effects on blood lipids between two yeast-leavened oat bran breads containing beta-glucan (6 g/d) of low or high average molecular weight (HMW) (217 or 797 kDa, respectively). The breads were fed to 22 volunteers (women, n = 11; men, n = 11) in a randomized, double-blind, crossover design. The participants ate one bread for 3 wk as part of their normal diet and switched breads after a 2-wk washout period. Blood samples were drawn from fasting subjects and analyzed for lipids, insulin, glucose, and alpha- and gamma-tocopherol. The two experimental oat breads did not differ in their effects on any of the variables measured. Compared to baseline, however, consumption of HMW bread increased serum insulin by 22.6% (P < 0.03) and decreased blood glucose concentrations by 3.4% (P < 0.05). These results suggest that the molecular weight, when beta-glucan is consumed in oat bran breads as part of the habitual diet, does not play an important physiological role in moderately hypercholesterolemic humans.