Time- and dose-dependent effect of psyllium on serum lipids in mild-to-moderate hypercholesterolemia: a meta-analysis of controlled clinical trials

Objectives: Evidences from randomized clinical trials and meta-analysis have claimed an association between the use of soluble dietary fiber from psyllium and a cholesterol-lowering effect. However, there is still uncertainty as to the dose-response relationship and its long-term lipid-lowering efficacy. This meta-analysis was primarily conducted to address the dose-response relationship between psyllium and serum cholesterol level and time-dependent effect of psyllium in mild-to-moderate hypercholesterolemic subjects. Methods: Twenty-one studies, which enrolled a total of 1030 and 687 subjects receiving psyllium or placebo, respectively, were included in the meta-analysis. The studies were randomized placebo-controlled trials, double blinded or open label, on subjects with mild-to-moderate hypercholesterolemia. The dose of psyllium was between 3.0 and 20.4 g per day and intervention period was more than 2 weeks. Any type of diet background was permitted. Diet lead-in period was between 0 and 8 weeks. Results: Compared with placebo, consumption of psyllium lowered serum total cholesterol by 0.375 mmol/l (95% Cl: 0.257-0.494 mmol/l), and LDL cholesterol by 0.278 mmol/l (95% Cl: 0.213-0.312 mmol/l). With random-effect meta-regression, a significant dose-response relationship were found between doses (3-20.4 g/day) and total cholesterol or LDL cholesterol changes. Regression model of total cholesterol was -0.0222+0.2061 x log (dose+1), and that of LDL cholesterol was 0.0485+0.1390 x log (dose+1). There was a time effect of psyllium on total cholesterol (equation: 6.3640-0.0316 x treatment period) and on LDL cholesterol (equation: 4.3134-0.0162 x treatment period), suggesting that psyllium reduced serum total cholesterol more quickly than LDL cholesterol. Conclusions: Psyllium could produce dose-and time-dependent serum cholesterol-lowering effect in mild and moderate hypercholesterolemic patients and would be useful as an adjunct to dietary therapy for the treatment of hypercholesterolemia. European Journal of Clinical Nutrition (2009) 63, 821-827; doi:10.1038/ejcn.2008.49; published online 5 November 2008