March 2011

Associations among Dietary Supplement Use and Dietary Activity Behaviors by Sex and Race/Ethnicity in a Representative Multiethnic Sample of 11th-Grade Students in Texas

Goldy, C. George, PhD; Andrew E. Springer, DrPH; Michele R. Forman, PhD; Deanna M. Hoelescher, PhD, RD, LD.

The purpose of this study was to examine the relationship between the use of dietary supplements and diet and activity patterns amongst a sample of adolescents, specifically 11th grade students in Texas. Dietary supplement use is very high amongst adolescents and in fact, one in four adolescents in the United States take some form of dietary supplement. The researchers of this study felt that there is little research done on dietary supplement use and diet and activity patterns among adolescents and that the studies that have been done have included samples of predominately Caucasian participants. Therefore, the researchers wanted to examine dietary supplement patterns amongst a multiethnic sample of adolescents.

There were 6,456 11th grade students that participated in this study from all over Texas in 2004 to 2005. The sampling frame included urban, suburban and rural schools. The participants were multiethnic with 50.6% being male, 48.8% white/other, 37% Hispanic and 14.2% African American. The mean age was 16.7 +/- 0.3 years. Parents or guardians of all participants signed a consent form before the study began.

The School Physical Activity and Nutrition (SPAN) instrument was used to determine the attitude towards and use of dietary supplements which specifically included "vitamin and mineral pills" and excluded amino acid or herbal supplements amongst 11th grade students in Texas. The SPAN instrument included a 24 hour food recall with 22 food markers specifically being examined. The food markers were separated into healthy and unhealthy categories with the healthy foods being whole grain products, fruits, vegetables and low-fat dairy products and the unhealthy foods included highly processed meats, sweets and soda. All instruments were distributed and collected on Tuesdays through Fridays and never after a school holiday in order to get an accurate reading on the participants' food recalls. The SPAN questionnaire asked about usual breakfast habits, frequencies of meals and also whether the participants where vegetarians. The activity questions looked at a 7 day recall examining participation in cardiovascular activities, strength training, team sports, PE classes and also the number of hours spent in front of the television or computer. Finally, trained professionals measured weight, height and BMI for each participant. The SPAN questionnaires were offered in both English and Spanish.

The results of this cross-sectional study found that amongst the entire sample, 23.6% of participants were taking a dietary supplement with white/other and Hispanics being the most prevalent amongst this percentage. African Americans were less likely to be taking a dietary supplement. Male supplement users were more likely to report a want to gain weight while female supplement users had a higher prevalance of being vegetarian than non-supplement users. There was no significant relationship between supplement users and BMI. However, supplement users were more likely to self report feelings of eating a healthier diet than their peers and they were found to be two to three times more likely to consume foods out of the healthy food marker group rather than the non-supplement users. In the overall sample it was found that supplement users were more likely to consume three or more meals a day, eat breakfast regularly and have a higher consumption of low-fat foods. As for physical activity, supplement users, no matter race or gender, were more likely to report participating in strength training exercises. Boys and white/others showed a positive relationship between all physical activities mentioned in the SPAN questionnaire and the use of supplements. Females, Hispanics and African Americans showed mixed results between the use of supplements and physical activity. Finally, white/other dietary supplement users were found to spend less time in front of the television or computer when compared to the other participants. African American adolescents held the lowest percentages in most of the categories mentioned.

The authors concluded by mentioning the importance of their findings in that dietary supplement use amongst adolescents may vary depending on gender and race/ethnicity. Therefore, the authors believe further research needs to be done in other parts of the United States to not only understand what motivates adolescents to take dietary supplements but in general, what are the overall benefits of supplement use amongst this particular population. The authors believe this kind of research may help health care professionals in working with and counseling adolescents who are taking or interested in taking dietary supplements.

George, G.C., Springer, A.E., Forman, M.R. & Hoelscher, D.M. Associations among Dietary Supplement Use and Dietary Activity Behaviors by Sex and Race/Ethnicity in a Representative Multiethnic Sample of 11th-Grade Students in Texas. Journal of the American Dietetic Association. 2011; 111(3): 385-393.

Related Article:
Reaves, L., Steffen, L.M., Dwyer, J.T., et. al. Vitamin Supplement Intake is Related to Dietary Intake and Physical Activity: The Child and Adolescent Trial for Cardiovascular Health (CATCH). Journal of the American Dietetic Association. 2006; 106(12): 2018-2023.