The effect of lactose maldigestion on the stools of young Tswana children.

During diarrhoeal disease, stool mass is usually increased. Lactose content of stools and stool pH have been used as tests for secondary lactose maldigestion. The effect of a lactose-free diet and various lactose loads on the stools of 30 children with primary adult-type lactose maldigestion was investigated. Stool mass following the lactose tolerance test was the largest (mean = 80 g/day); that following the milk tolerance test less--62 g (not significantly), that on a milk containing diet significantly less (35 g), while stool mass produced on a lactose-free diet (22 g) was significantly less than that produced on any of the three lactose-containing diets. The stool pH on a milk containing diet (mean = 6.3) was significantly higher than those of the three other diets (after lactose tolerance test, pH = 5.85; after milk tolerance test, pH = 5.86; after lactose-free diet, pH = 5.83). Although stool bulk was greater when these lactose maldigesters were consuming a lactose containing diet, it was still considerably less than the stool mass associated with secondary lactose maldigestion, which is believed to be a cause of diarrhoeal disease. In contrast, the primary adult-type of lactose maldigestion does not commonly cause diarrhoea, as shown in this study.