American Journal of Clinical Nutrition, Vol 28, 238-241, Copyright © 1975 by The American Society for Clinical Nutrition, Inc

ORIGINAL RESEARCH COMMUNICATIONS

Effect of dietary lactose on the absorption of protein, fat and calcium in the postweaning rat

J Leichter and AF Tolensky

To assess the effect of dietary lactose on the intestinal absorption of protein, fat and calcium in lactose intolerance due to low levels of intestinal lactase, balance studies were carried out on postweaning rats (initial weight 164 g) for a period of 10 days. The experimental diets contained either 10% or 30% lactose, while in the control diets the lactose was replaced with equivalent amounts of sucrose. The excretions of fecal and urinary nitrogen, calcium and fat are expressed as precent of intake over the 10-day period. The fecal excretion of nitrogen and fat was significantly higher in the lactose groups (P less than 0.05). The fecal calcium excretion, however, was lower in the lactose groups, the difference being significantly only in the case of the 30% lactose diet (P less than 0.001). There was no difference in urinary nitrogen excretion between the lactose and sucrose groups, but urinary calcium excretion was significantly higher in the rats fed the 30% lactose diet (P less than 0.01). These findings suggest that dietary lactose may reduce the absorption of protein and fat, but not of calcium, in individuals with low levels of intestinal lactase activity.

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