Fat containing stearic acid increases fecal neutral steroid excretion and catabolism of low density lipoproteins without affecting plasma cholesterol concentration in hamsters fed a cholesterol-containing diet.

ABSTRACT

To examine the effect of different saturated fatty acids on the dietary cholesterol-induced elevation of serum cholesterol concentration and suppression of LDL catabolism, for 4 wk hamsters were fed purified diets containing 8% purified fats in which saturated fatty acids, lauric, myristic, palmitic and stearic acids were the sole variable. The dietary fat was composed of 50% saturated fatty acid, 30% oleic acid and 20% linoleic acid (polyunsaturatedsaturated = 0.4). In hamsters fed the cholesterol-containing diet, fat containing stearic acid, compared with the fats containing other saturated fatty acids resulted in greater fractional catabolic rate of [125I]-labeled homologous LDL, greater fecal excretion of neutral steroids and lower liver cholesterol concentration, although the elevation of serum cholesterol concentration due to consuming a cholesterol-containing diet was not ameliorated. Stearic acid fat resulted in greater excretion of fecal fatty acids and lower apparent absorption of the dietary fats in hamsters fed diets with and without cholesterol. In hamsters fed the cholesterol-free diets, type of dietary fat did not affect the fractional catabolic rate of LDL, although stearic acid fat resulted in greater fecal neutral steroid excretion and lower serum and liver cholesterol concentrations. These observations suggested that purified fat containing stearic acid results in lower plasma cholesterol concentration in hamsters via stimulation of neutral steroid excretion, but addition of cholesterol to the diets obscures this effect.