Effect of nicotinic acid on catabolism and synthesis of cholesterol in man

Abstract

Sterol balance studies carried out in five hypercholesterolemic human subjects before and during the first 9–14 days on nicotinic acid treatment showed that the nicotinic acid-induced fall in serum cholesterol level was associated with a significant increase in the fecal excretion of neutral steroids of endogenous origin. The output of fecal bile acids and of dietary unabsorbed cholesterol appeared to rise less consistently. The increment of fecal steroid excretion was higher in three and lower in two subjects than the respective decrement of serum cholesterol. Since, in addition, the slope of the serum cholesterol specific activity-time curve decreased or remained unchanged during the nicotinic acid-induced decrease of serum cholesterol it was suggested that the enhanced cholesterol catabolism was associated with increased mobilization of tissue cholesterol and possibly also with reduced cholesterol synthesis.