Multivitamin/mineral supplement are regularly taken by over 70 per cent of American adults and make up a substantial part of the $23bn spent by consumers every year on dietary supplements. Health conscious adolescents also appear to be supplementing their diets.
"Our findings show that not only were supplement users more likely to be physically active, but to also have many other healthful characteristics," wrote lead author Lindsay Reaves from the University of Minneapolis.
The National Institutes of Health-funded study was part of the larger Child and Adolescent Trial for Cardiovascular Health (CATCH), and involved 2761 twelfth-graders from 40 schools in California, Louisiana, Minnesota, and Texas.
Twenty-five percent of those surveyed were regular multi-vitamin users, and the focus of the study was only on multi-vitamin supplement use and no evaluation of other supplements was performed.
The authors of the new survey, published in the current issue of the Journal of the American Dietetic Association, said that the reasons why these adolescents were taking the supplements were unclear and called for further studies to understand why healthy adolescents were supplementing their diets with multi-vitamins.
Dietary assessment was performed using a validated 149-item Youth Adolescent Food Frequency Questionnaire (FFQ) and information about lifestyle habits was collected to quantify multiple-vitamin supplement use, physical activities, hours of television watching, and smoking.
The researchers report that supplement users were more likely to be physically active, watch less television, and were less likely to be overweight.
They were also associated with higher average daily intakes food groups, such as whole grain, fruit, vegetables, dairy, and fish, and lower daily intakes of meat, fried food, and soft drinks.
"Adolescents who use multiple vitamin supplements have more healthful dietary and lifestyle behaviors than nonusers. Further study on supplement use by adolescents, including other types of supplements used and reasons for use, is warranted," wrote Reaves.
The researchers said that the research had clear implications for health professionals who work with adolescents: "Vitamin/mineral supplements contribute to total nutrient intake and adolescents should be asked about frequency of use, type of supplement taken, and reasons why they are used.
"Healthy adolescents who have more healthful dietary patterns are more likely to be supplement users; therefore, these individuals are likely at a lower risk of having poor nutritional status than healthy nonusers.
"Supplements are not substitutes for healthful dietary patterns, and adolescents should be encouraged to adopt healthful patterns rather than rely on dietary supplementation for adequate nutrient intake."
Source: Journal of the American Dietetic Association December 2006, Volume 106, Issue 12, Pages 2018-2023 "Vitamin Supplement Intake Is Related to Dietary Intake and Physical Activity: The Child and Adolescent Trial for Cardiovascular Health (CATCH)" Authors: L. Reaves, L.M. Steffen, J.T. Dwyer, L.S. Webber, L.A. Lytle, H.A. Feldman, D.M. Hoelscher, M.M. Zive and S.K. Osganian