Prevalence of lactose maldigestion. Influence and interaction of age, race, and sex.

Ninety-eight adults ranging from 20 to 89 years in age (52 blacks, 46 whites, 48 males, 50 females) were tested for lactose maldigestion by breath hydrogen analysis after consuming milk containing 16.5 g lactose (360 ml milk). Older adults (> or = 50 years) displayed a significantly higher incidence (46%) of lactose maldigestion than younger adults (< 50 years, 26%). In younger adults there were 2.4 times more maldigesters in blacks than in whites, while in older groups this ratio was 3.6. Level of breath hydrogen significantly increased with age up to the age group of 60-69 years. The interaction between age groups and race was highly significant. Of the maldigesters, 63% reported symptoms and 3% of the total sample reported severe symptoms. Results of this study indicate that the prevalance of lactose maldigestion significantly increases with age in blacks compared to whites and that the magnitude of the problem may be greater in black maldigesters than in white maldigesters.