Study objectives: To determine whether orlistat causes fat-soluble vitamin deficiencies in African-American and Caucasian adolescents.
Design: Prospective, open-label pilot study.
Setting: Warren Grant Magnuson Clinical Center of the National Institutes of Health.
Patients: Seventeen adolescents with body mass indexes above the 95th percentile for age, race, and gender who also had at least one obesity-related comorbid condition.
Intervention: Subjects received orlistat 120 mg 3 times/day and a daily multivitamin supplement containing vitamin A 5000 IU, vitamin D 400 IU, vitamin E 300 IU, and vitamin K 25 microg.
Measurements and main results: During 3-6 months of orlistat treatment, acute absorption of retinol (vitamin A) was not significantly altered, but absorption of alpha-tocopherol (vitamin E) was significantly reduced compared with baseline levels (p<0.001). Serum levels of vitamins A and E did not change significantly; however, there was a nonsignificant decrease in vitamin K. Mean vitamin D levels were significantly reduced compared with baseline (p<0.02) after 1 month of orlistat, despite multivitamin supplementation.
Conclusion: It may be prudent to monitor vitamin D concentrations in adolescents who take orlistat, even when a multivitamin is prescribed.