EFFECT OF PSYLLIUM IN HYPERCHOLESTEROLEMIA AT 2 MONOUNSATURATED FATTY-ACID INTAKES

We performed two studies to determine whether the lipid-lowering effec t of viscous soluble fiber was modified by monounsaturated fatty acid (MUFA). First, psyllium (1.4 g/MJ) was compared with wheat bran (contr ol) in 1-mo metabolic diets by using a randomized crossover design (n = 32 hyperlipidemic subjects). The background diet contained approxima te to 6% of energy as MUFA (20% of total fat). The second study (n = 2 7 hyperlipidemic subjects) was similar to the first but the background diet contained approximate to 12% MUFA (29% of total fat) because of the addition of canola oil. At both fat intakes, psyllium resulted in significant reductions in total, low-density-lipoprotein (LDL), and hi gh-density-lipoprotein (HDL) cholesterol-compared with the wheat bran control. For the psyllium diet at 6% compared with 12% MUFA, the decre ases in LDL cholesterol were 12.3 +/- 1.5% (P < 0.001) and 15.3 +/- 2. 4% (P < 0.001), respectively. With the higher MUFA diet triacylglycero l fell significantly over the control phase (16.6 +/- 5.5%, P = 0.006) and the ratio of LDL to HDL cholesterol fell significantly over the p syllium phase (7.3 +/- 2.8%, P = 0.015). Psyllium and MUFA intakes wer e negatively related to the percentage change in the ratio of LDL to H DL cholesterol (r = -0.34, P = 0.019 and r = -0.44, P = 0.002, respect ively). Chenodeoxycholate synthesis rate increased (30 +/- 13%, P = 0. 038) with the psyllium diet in the 12 subjects in whom this was assess ed. We conclude that psyllium lowered LDL- and HDL-cholesterol concent rations similarly at both MUFA intakes. However, there may be some adv antage in combining soluble fiber and MUFA to reduce the ratio of LDL to HDL cholesterol.