Changes in cholesterol metabolism In infants in response to dietary cholesterol and fat

Abstract

The regulation of the serum cholesterol level in infancy is not understood but it has been suggested that it is less precise than in adulthood. Ten infants, ages 3 to 16 months, were studied during two periods of 1 month each, first consuming a low-cholesterol, polyunsaturated fatty acid-rich diet and later a cholesterol containing, polyunsaturated fatty acid-poor diet. Changes in serum cholesterol, bile acid excretion, and net sterol balance (sterol excretion minus cholesterol intake) were measured at the end of each period. The serum cholesterol level rose with the second diet in all infants by from 30 to 111 mg/100 ml. The theoretical response that might be expected in adults to a similar change in cholesterol and fat intake either resembled that, or was not less than that, shown by seven of the infants, while three infants showed a larger than predicted difference in serum cholesterol between the diets. The mean observed and predicted differences in the serum cholesterol level were, respectively, 56 and 58 mg/100 ml suggesting that the magnitude of the response becomes established in early life. Bile acid excretion was significantly higher with dietary polyunsaturated fatty acids, probably explaining some of the effect on the serum cholesterol. The sterol balance data showed that the net sterol balance fell substantially during the consumption of cholesterol in seven of the 10 infants. Although a steady state for cholesterol metabolism is not being claimed for growing infants, the fall in the net sterol balance is strongly suggestive of lessened endogenous cholesterol synthesis as reported in adults.