Is barley as effective as oats in lowering cholesterol? - Cardiovascular Disease

Nutrition Research Newsletter, Nov, 2003 by G. Keogh, G. Cooper, T. Mulvey

There is a well-established protective effect of dietary fiber against cardiovascular disease (CVD). Specifically, an increase in intake of soluble fiber from guar gum and cereals such as oats and psyllium has been shown to have a hypocholesterolemic effect. Recently, the US Food and Drug Administration has endorsed the relation between an increase in soluble fiber and a decrease in serum total cholesterol by allowing health claims for oats and for psyllium fiber. The active component in oats has been shown to be the linear mixed-link (1, 3)(1, 4)-beta-D-glucan (beta-glucan). Beta-glucan reduces serum total cholesterol by 5% to 10%. In oats beta-glucan is present at close to 4% while barley contains 5% to 10% beta-glucan by weight. Therefore, it is expected that barley may have similar cholesterol lowering effects, however, little research has been done to investigate this hypothesis.

Barley is not a readily accepted food source, therefore, it is unlikely that adequate amounts could be incorporated into the diet to achieve the recommended intake of 3 gms of beta-glucan per day without enrichment of the product. The goal of a recent study was to assess whether a highly beta-glucan-enriched barley (75% by weight) would result in a clinically significant improvement in CVD risk in a group of men with mild hypercholesterolemia.

Subjects included 18 males, aged 18 to 65 years who had mildly elevated concentrations of LDL cholesterol (more than 3.5 mmol/L), no current drug treatment for hyperlipidemia and no history of CVD. The study was a randomized crossover intervention trial in which participants were blinded to treatment. Each of the two intervention periods was four weeks in duration and was separated by a minimum washout period of four weeks. Blood and urine samples were routinely collected and an oral glucose tolerance test was performed before day one and on day 29. Weight was measured daily and blood samples were analyzed for total, LDL, and HDL cholesterol; triacylglycerol; fasting plasma glucose; and postprandial plasma glucose.

The barley used in this trial was a highly enriched barley-fiber product, a gelling form of beta-glucan, produced from high beta-glucan content barley that was milled and sieved to separate the starch and cell-wall material. The active treatment consisted of a daily supplement of 0.67 gms barley, beta-glucan/MJ of the total diet and control comprised an isoenergetic amount of monosaccharide glucose of 0.54 gms/MJ of the total diet. The beta-glucan treatment and glucose control supplements were incorporated into snacks and meats consumed during the day. The background diet ensured that the only nutrient that differed between treatments was beta-glucan.

There was no significant change ([DELTA]) in total ([DELTA] = -0.08 mmol/L, -1.3%0 LDL ([DELTA] = -0.15 mmol/L, -3.8%), or HDL ([DELTA] = 0 mmol/L) cholesterol or in triacylglycerol ([DELTA]= 0.18 mmol/L), fasting glucose ([DELTA] = -0.05 mmol/L), or postprandial glucose when analyzed between treatments (P > 0.05; ANOVA).

This data reveals no strong evidence to suggest that the beta-glucan-enriched barley had any significant impact on lipid profiles in a small group of mildly hypercholesterolemic men.

G. Keogh, G. Cooper, T. Mulvey, et al. Randomized controlled crossover study of the effect of a highly beta-glucan-enriched barley on cardiovascular disease risk factors in mildly hypercholesterolemic men Am J Clin Nutr; 78: 711-718 (October, 2003). [Correspondence: SD Poppitt, Department of Medicine, University of Auckland, Private Bag 92019, Auckland, New Zealand. E-mail: s.poppitt@auckland.ac.nz].