Diagnosis, symptoms, and calcium intakes of individuals with self-reported lactose intolerance

Objective: To determine methods of diagnosis, symptoms, and calcium intake from food and supplements for individuals with self-reported lactose intolerance. Methods/Design: Cross-sectional survey using a mailed questionnaire. Subjects/Setting: A convenience sample of 189 adults with self-reported lactose intolerance living in the metropolitan area of Vancouver Canada responded to posters or advertisements, and 159 returned completed questionnaires. Measures of Outcome: Methods of diagnosis, symptoms experienced and their severity were self-reported. Estimated calcium intake from food and supplements was assessed using a food frequency questionnaire. Data were analyzed using descriptive statistics, chi-square, Pearson correlation analysis, t-tests and Analysis of Variance. Results: Participants were 47 +/- 15 years of age; 72% female and 28% male; 67% Caucasian; and 54% had self-diagnosed their lactose intolerance. Of the 42% diagnosed by a physician, only 10% had been diagnosed by valid tests. Mean estimated food calcium intake was 591 +/- 382 mg/d and did not differ between those who were self- or physician-diagnosed. Only 11.5% of participants met their age-appropriate Adequate Intake (AI) from food calcium sources alone. Calcium supplements were used by 65% and provided an average of 746 +/- 703 mg calcium/day to those who used them; mean intakes of this group met the AI. Conclusions: Calcium intake from food sources alone is inadequate to meet the AI in individuals with self-reported lactose intolerance. Physicians managing lactose intolerance need current information on how the AI can be met through appropriate food choices and possible supplementation.