Background-Uncontrolled studies of lactose intolerant subjects have shown that symptom severity decreases after chronic lactose consumption. Adaptation of the colonic flora might explain this improvement. Aims-To compare the eVects of regular administration of either lactose or sucrose on clinical tolerance and bacterial adaptation to lactose. Methods-Forty six lactose intolerant subjects underwent two 50 g lactose challenges on days 1 and 15. Between these days they were given 34 g of lactose or sucrose per day, in a double blind protocol. Stool samples were obtained on days 0 and 14, to measure faecal -galactosidase and pH. Symptoms, breath H 2 excretion, faecal weight and electrolytes, and orofaecal transit time were assessed. Results-Except for faecal weight, symptoms were significantly milder during the second challenge in both groups, and covariance analysis showed no statistical difference between them. In the lactose group, but not in the sucrose group, faecal -galactosidase activity increased, pH dropped, and breath H 2 excretion decreased. Conclusion-Bacterial adaptation occurred when lactose intolerant subjects ingested lactose for 13 days, and all symptoms except diarrhoea regressed. Clinical improvement was also observed in the control group which displayed no signs of metabolic adaptation. This suggests that improved clinical tolerance may be just a placebo eVect. (Gut 1997; 41: 632-635)

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This study aimed to compare the absorption and tolerance of 20-g lactose loads as milk and yogurt in 17 patients with short-bowel syndrome with either a terminal jejunostomy (group A, n = 6) or a jejunocolic anastomosis (group B, n = 11). Records and measurements during the 8 h after the meals included fecal weight, symptoms, lactose and hexose flow rates in stomal effluents (group A), and breath-hydrogen excretion (group B). In group A lactose was better absorbed in the form of yogurt than in the form of milk (mean +/- SE: 76 +/- 6% vs 50 +/- 9%, P < 0.05), whereas no significant difference could be detected by using the breath-hydrogen test in group B. The excellent tolerance to 20 g lactose from milk and yogurt suggests that lactose should not be excluded from the diet of these subjects.

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