Objective: The purpose of this study was to determine associations among lactose maldigestion status, perceived milk intolerance, dietary calcium intake, and bone mineral content in early adolescent girls.
Methods: Subjects were 291 girls who participated in a substudy of the multiple-site project Adequate Calcium Today. Lactose maldigestion status was determined with hydrogen breath testing, and questionnaires were used to assess perceived milk intolerance. Dietary calcium intake was estimated from a semiquantitative food frequency questionnaire. Anthropometric and dual-energy x-ray absorptiometric measurements (total body, spine L2-L4, total hip, and hip femoral neck) were standardized across sites.
Results: Of the 230 girls who completed breath hydrogen testing, 65 were Asian, 76 were Hispanic, and 89 were non-Hispanic white. A total of 100 girls experienced increases in breath hydrogen levels of >20 ppm and were classified as lactose maldigesters. Of the 246 participants who completed useable perceived milk intolerance questionnaires, 47 considered themselves to be milk intolerant. Of the 47 girls self-reporting perceived milk intolerance, 40 completed breath hydrogen testing and 22 were not maldigesters. Girls with perceived milk intolerance consumed an average of 212 mg of total food calcium per day less than girls without perceived milk intolerance. Spinal bone mineral content was significantly lower in the girls with perceived milk intolerance, compared with the girls without perceived milk intolerance. When girls with lactose maldigestion were compared with girls without lactose maldigestion, there were no significant differences in calcium intake or bone measures.
Conclusions: These results suggest that, starting as early as 10 years of age, self-imposed restriction of dairy foods because of perceived milk intolerance is associated with lower spinal bone mineral content values. The long-term influence of these behaviors may contribute to later risk for osteoporosis.