Relationships between vitamin and mineral supplement use, dietary intake, and dietary adequacy among adolescents

Objective: To examine patterns of supplement use among US adolescents and the relationship between supplement use and dietary intake and adequacy. Design: Adolescents self-reported 2 days of food intake using the 24-hour recall method and supplement use during a personal interview conducted as part of the 1994 Continuing Survey of Food Intakes of Individuals (CSFII). Subjects: A national sample of 423 adolescents included in the 1994 CSFII survey. Statistical analysis: χ² analysis was used to determine which demographic factors were significantly related to patterns of supplement use. Weighted percentages of adolescents by category of supplement use for selected vitamins and minerals (calcium; iron; zinc; folic acid; and vitamins A, B-6, C, and E) are presented. Relationships between dietary intake of macronutrients and vitamins and minerals among adolescents and supplement use were determined using a least-squares model of general linear regression. Results: Approximately one-third of adolescents reported using supplements, with 15.6% of youth using them on a daily basis. The majority of supplement users reported taking multivitamins (N=95; 65.5%) whereas only one-third of supplement users reported taking individual vitamins or minerals. Supplement use was found to vary by gender, household size, and US region of residence. Adolescents who reported using supplements had higher mean dietary intakes of most micronutrients and lower intakes of total and saturated fat than those who did not use supplements. More than one-third of adolescents had dietary intakes of vitamins A and E, calcium, and zinc that were <75% of the US Recommended Dietary Allowance. Applications/Conclusions: The majority of US adolescents do not use vitamin or mineral supplements. Interestingly, adolescents who do use supplements, even on an infrequent basis, consume diets that are more nutrient-dense than those who do not use supplements. Dietary intakes of several micronutrients were inadequate among all adolescents in this study, regardless of supplement use status. There is a need to develop and implement programs aimed at improving the dietary intakes of US adolescents.