Efficacy of psyllium in reducing serum cholesterol levels in hypercholesterolemic patients on high- or low-fat diets

■ Objectives: To determine the efficacy of psyllium in reducing serum cholesterol levels in patients on high-or low-fat diets. ■ Design: Double-blind, placebo-controlled, 16-week parallel trial. The study included an 8-week baseline period and an 8-week treatment period. ■ Patients: Healthy men and women, 21 to 70 years old, with primary hypercholesterolemia (total serum cholesterol ≥5.7 mmol/L [220 mg/dL]). Thirty-seven participants followed a high-fat diet and 81 participants followed a low-fat diet. ■ Intervention: Participants were randomly assigned to either psyllium, 5.1 g twice a day, or placebo. ■ Measurements: Fasting lipid and apolipoprotein concentrations, including direct low-density lipoprotein (LDL) cholesterol quantification; nutritional analyses of 4 days of 7-day food records to monitor dietary compliance; and physical examinations, clinical chemistry and hematologic studies, and urinalysis to assess treatment safety. ■ Main Results: Psyllium recipients in both the highland low-fat diet groups showed small but significant decreases (P < 0.05) in total cholesterol and low-density lipoprotein (LDL) cholesterol levels. Total cholesterol and LDL cholesterol levels decreased 5.8% and 7.2%, respectively, in psyllium recipients on high-fat diets and 4.2% and 6.4%, respectively, in psyllium recipients on low-fat diets. No significant difference was seen in LDL cholesterol response when psyllium recipients on low- and high-fat diets were compared (P > 0.2). No significant reductions in lipid levels were observed in placebo recipients. Based on the National Cholesterol Education Program LDL cholesterol classification system, 39% of the psyllium recipients improved in LDL cholesterol classification (P < 0.0001) compared with 20.3% of placebo recipients (P > 0.2). ■ Conclusions: Psyllium produces a modest but significant improvement in total cholesterol and LDL cholesterol levels in persons on either low-fat or high-fat diets. Psyllium, when added to a prescribed low-fat diet, may obviate the need for typical lipid-lowering medications or may prove to be a valuable adjunct to other treatments in patients with moderately elevated LDL cholesterol levels.