Soluble fiber intake at a dose approved by the US Food and Drug Administration for a claim of health benefits: serum lipid risk factors for cardiovascular disease assessed in a randomized controlled crossover trial

Abstract

The US Food and Drug Administration (FDA) approved health claims for 2 dietary fibers, beta-glucan (0.75 g/serving) and psyllium (1.78 g/serving), on the assumption that 4 servings/d would reduce cardiovascular disease risk. We assessed the efficacy of this dose of fibers in reducing serum lipid risk factors for cardiovascular disease. Sixty-eight hyperlipidemic adults consumed a test (high-fiber) and a control low-fat (25% of energy), low-cholesterol (<150 mg/d) diet for 1 mo each in a randomized crossover study. The high-fiber diet included 4 servings/d of foods containing beta-glucan or psyllium that delivered 8 g/d more soluble fiber than did similar, unsupplemented foods in the control diet. Fasting blood samples and blood pressure readings were obtained at baseline and weeks 2 and 4, and the subjects' weight was monitored weekly. Compared with the control diet, the high-fiber diet reduced total cholesterol (2.1 +/- 0.7%; P = 0.003), total:HDL cholesterol (2.9 +/- 0.8%; P = 0.001), LDL:HDL cholesterol (2.4 +/- 1.0%; P = 0.015), and apolipoprotein B:A-I (1.4 +/- 0.8%; P = 0.076). Applying the Framingham cardiovascular disease risk equation to the data confirmed a reduction in risk of 4.2 +/- 1.4% (P = 0.003). Small reductions in blood pressure were found after both diets. The subjects reported no significant differences in palatability or gastrointestinal symptoms between the diets. The reduction in serum lipid risk factors for cardiovascular disease supports the FDA's approval of a health claim for a dietary fiber intake of 4 servings/d. Although relatively small in terms of patient treatment, the reduction in cardiovascular disease risk is likely to be significant on a population basis.