The effect of dietary sodium in infancy on blood pressure and related factors. Studies of infants fed salted and unsalted diets for five months at eight months and eight years of age.

The results of animal and epidemiological studies suggest commercially salted infant foods may predipose infants to hypertension. Testing this hypothesis, two groups of black male infants were fed identical foods with and without added salts for 5 months starting at 3 months of age. These diets, which provided 1.93+/-0.10 and 9.25+/-0.05 mEq Na/100 kcal, did not result in a significant difference in blood pressure at 8 months or 8 years of age. Blood pressure was significantly correlated with weight factors, particularly at 8 years, but not with Na intake, Na or Na/K excretion or plasma renin at 8 months. Significantly increased sodium and potassium excretion was noted on the salted diet and significantly increased aldosterone excretion was noted on the unsalted diet. A 6% expansion in extra-cellular fluid volume for the high sodium group was statistically significant but was not correlated with blood pressure or urine volume and did not result in edema or increased weight. There was no indication that the salted foods imprinted a preference for salt at 8 years. It was concluded that a salt intake representing the 99th percentile of sodium intake by U.S. infants in 1969 had no hypertensive effect in infancy or at 8 years of age. Nor did it imprint a preference for salt at 8 years.