Improved lactose digestion and intolerance among African-American adolescent girls fed a dairy-rich diet

Objective To determine whether African-American adolescent girls who were f ed a dairy-rich diet for 21 days could adapt to lactose, experiencing an ov erall improvement in lactose tolerance as well as a decrease in hydrogen ga s production. Design Twenty-one-day dietary intervention study. Subjects/setting Seventeen of 21 African-American girls (aged 11 to 15 year s) enrolled in a calcium metabolism study chose to participate in the lacto se tolerance study. Subjects were screened for any diseases, conditions, or medications that might alter calcium metabolism or colonic fermentation. S ubjects were housed in a fraternity on the Purdue University, West Lafayett e, Ind, campus, and were supervised 24 hours a day. Intervention Subjects consumed a dairy-based diet averaging 1,200 mg calciu m and 33 g lactose per day for 21 days. Lactose digestion was assessed by a n 8-hour breath hydrogen test on days 1 and 21, and symptoms of intolerance (abdominal pain, bloating, flatulence, and diarrhea) were evaluated hourly on a ranked scale during the breath hydrogen tests and once each evening d uring the 21-day feeding period. Main outcome measures A comparison of breath hydrogen production and gastro intestinal symptoms at the beginning and end of the study. Statistical analyses performed The Wilcoxon signed ranks test was used to c ompare the area under the curve for the 2 breath hydrogen tests. Spearman's p test for trend was used to determine whether there was a change in sympt oms. All statistical analyses were 2-tailed and significance was set at P=. 05. Results Fourteen of the 17 subjects had lactose maldigestion. Breath hydrog en excretion decreased significantly (P < .03) from the beginning (148.3 +/ - 27.0 ppmxhours) to the end (100.7 +/- 19.3 ppmxhours) of the 21-day perio d. Gastrointestinal symptoms were negligible during both the breath hydroge n tests as were symptoms during the 21-day period. Applications/conclusions The diet was well tolerated by the subjects. Furth ermore, the decrease in breath hydrogen suggests colonic adaptation to the high-lactose diet. The results indicate that lactose maldigestion should no t be a restricting factor in developing adequate calcium diets for this pop ulation. The existence of lactose maldigestion does not result in lactose i ntolerance in this population when it is fed a dairy-rich diet.