Absorption, metabolism, and serum concentrations of cholesterol in vegetarians: effects of cholesterol feeding

Abstract

Serum concentrations and metabolism of cholesterol were studied in vegetarians basally and during a dietary cholesterol load. Cholesterol absorption efficiency was normal and synthesis was slightly enhanced, even though serum cholesterol precursors were not increased. The serum concentrations of total and low-density-lipoprotein cholesterol were decreased proportionally to the reduced intake and absolute absorption of cholesterol. Fecal plant sterols were negatively correlated with the absorption efficiency of cholesterol and positively with fecal sterols and cholesterol synthesis, suggesting interference of high plant sterol intakes with cholesterol absorption. Cholesterol saturation and bile acid composition of the bile were not changed. The increased serum plant sterol-cholesterol ratios were positively related to the intake and negatively to the biliary secretion of plant sterols. Cholesterol feeding increased absolute cholesterol absorption and serum concentrations of total and low-density-lipoprotein cholesterol, did not change absorption efficiency or synthesis of cholesterol, but increased fecal cholestanol excretion.

Plant Sterols in Serum and in Atherosclerotic Plaques of Patients Undergoing Carotid Endarterectomy

“…The question may sound naive, because vegetarianism is considered to be healthy as far as arteriosclerotic arterial disease is considered, mainly because body weight of the subjects is low, hypertension is rarely observed, occurrence of type 2 diabetes is rare, and hyperlipidemia, especially hypercholesterolemia, is infrequent. In addition, serum plant sterol concentrations, despite relatively high plant sterol intake, are not excessively high (15). The nature may have considered that high plant sterol concentrations in animal cell membranes offer a possible danger for well being of the cell owner, limiting intestinal absorption of plant sterols from diet to roughly one-fifth to one-tenth of that of cholesterol.…”

Plasma plant sterols serve as poor markers of cholesterol absorption in man

“…This absence of a direct correlation between plasma plant sterol levels and cholesterol absorption may not be surprising when the metabolic routes of the different sterols are compared. Despite their high degree of structural similarity ( 37 ), there are numerous differences in the metabolic fate of plant sterols compared with cholesterol within the human body. Plant sterols are not endogenously synthesized and derive strictly from the diet.…”

Lipid-lowering Activity of Natural and Semi-Synthetic Sterols and Stanols

“…Sitostanol and campestanol are the most common plant stanols. The dietary intake of plant sterols ranges from 150 to 450 mg/day and can be as high as 600 mg/day in vegetarians (11). In contrast, the dietary intake of plant stanols is usually only about 50 mg/day (9,12).…”