In trials to find out whether direct stimulation of respiratory enzyme activity would influence serum cholesterol, nicotinic acid, which is a component of the respiratory coenzyme system, was given to rabbits by mouth 3 times daily in doses of from 0.18 to 0.045 g.; it was usually followed by a decrease in serum cholesterol.

In 11 healthy medical students, 4 g. nicotinic acid given by mouth in 4 spaced doses of 1 g. during 24 hr. was followed by an average decrease of 8.4 per cent. in serum cholesterol of which the previous average value had been 204 mg. per 100 ml. In a series of 57 patients who received a single dose of 1 g. nicotinic acid, a decrease in serum cholesterol occurred also, the amount of the decrease depending on the initial value. If the total of 68 subjects was divided into 2 groups with serum cholesterol values under and over 250 mg. per 100 ml., the average percentage decrease in the first group was 6.4, and in the second 21.7.