Psyllium husk II: effect on the metabolism of apolipoprotein B in African green monkeys

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Abstract
Dietary psyllium's ability to reduce low-den-sity-lipoprotein (LDL) cholesterol is presumably mediated by increased LDL catabolism and/or reduced LDL synthesis. To distinguish between these possibilities, apolipoprotein B (apo B) metabolism was studied in adult male African green monkeys consuming one of three semipurified diets: low-cholesterol cellulose (LCC), high-cholesterol cellulose (HCC), or high-cholesterol psyllium (HCP). 131I-labeled LDL and 125I-labeled VLDL were injected simultaneously into animals; blood samples were drawn at selected times and apo B specific activity determined in VLDL, IDL, and LDL. Based on a multicompartmental model, LDL apo B pool size and de novo apo B transport were elevated significantly in HCC animals compared with HCP and LCC animals. Differences in LDL transport, although not significant, paralleled differences observed in LDL apo B pool size. Fractional catabolic rates were similar among groups (HCC 0.040 ± 0.010; HCP 0.042 ± 0.009, and LCC 0.043 ± 0.004 pools/ h). These data suggest that dietary psyllium reduces plasma cholesterol concentrations by decreasing LDL synthesis.