More than one-third of the 10 828 children and adolescents 2 to 17 years of age in the 1999–2004 NHANES took VM supplements in the preceding month. Our results supported our hypothesis that underweight children would have the highest use of VM supplements. However, in contrast to what we expected to find, children and adolescents with healthier nutrition, more active lifestyles, greater food security, and greater health care access were more likely to use VM supplements.
Published literature supports the high prevalence of VM use. More than half of all 3-year-olds in the 1991 Longitudinal Follow-up to the 1988 National Maternal and Infant Health Survey used a VM supplement.9
Consistent with our study’s findings, children who received supplementation tended to have eating problems or poor appetites. Mothers who gave their children supplements were more likely to be non-Hispanic white, married, and older and have higher education and greater household income than mothers who did not give their children supplements.9
Data from the 1981 Child Health Supplement to the National Health Interview Survey (NHIS) demonstrate that approximately 50% of children from birth to 6 years of age received a VM supplement.10
In a study using 1986 NHIS data, 43% of children aged 2 to 6 years received VM supplements in the previous 2 weeks.1
Results from the Fourth Child and Adolescent Trial for Cardiovascular Health study demonstrated that one in four 12th graders used VM supplements.4,11
Consistent with our findings, other studies have demonstrated that adolescents who use VM supplements tend to have more healthful diets, lower television viewing, greater levels of physical activity, greater participation in team and organized sports, and less obesity than those who do not.4,5
More recently, Picciano et al20
examined dietary supplement use among infants, children, and adolescents in the United States using the 1999–2002 NHANES data set. Dietary supplement use was associated with higher family income, not participating in the WIC program, a smoke-free environment, less screen-viewing time (television, video games, and computer use), and lower BMI. The association of dietary supplement (specifically VM) use with nutrition, food security, physical activity, and health care access was not examined.20
Therefore, analyses of other national data sets show demographic and lifestyle characteristic associations similar to those in our study, with higher VM use among non-Hispanic white individuals and those with higher socioeconomic status, healthier diets, and level of physical activity as well as those with less obesity.
Dixon et al21
analyzed the Third NHANES to determine if dietary intakes and serum nutrient levels differed between adults from food-insufficient and food-sufficient families. After adjusting for family income, adults from food-insufficient families had lower intakes of milk products, fruits and vegetables, energy, calcium, vitamin E, vitamin B6
, iron, and zinc. Our study did not find any association between adult or child food security and VM use after controlling for poverty.
Strengths of our study are that the NHANES yields a nationally representative sample and provides respondent sampling weights to account for nonresponse and selection bias. The in-person interview and rigorous methods of classifying VM supplements enable high-quality data collection. We acknowledge the following limitations of this study: (1) We did not include other dietary supplement use in our analyses; the rationale for focusing on VM supplements was that published data demonstrate that VMs are the most commonly used dietary supplements both in children and adults.2
(2) Analysis of individual components of VM preparations was beyond the scope of this study. (3) The NHANES data use a short referent time frame of the past 30 days to assess VM supplement use. Although this time frame is used to increase accuracy of self-report and for comparability with other NHANES data, it may not provide a complete picture of VM use. For example, the short time frame may not capture episodic use of VM supplements, such as supplemental vitamin C use during viral upper respiratory tract infections, if the most recent infection was prior to the 30-day period. (4) Since NHANES data are cross-sectional, analyses of VM supplement use with the lifestyle and health conditions measured in NHANES cannot presume causality, but only an association. In spite of these limitations, we believe that the results of our study offer guidance to health care providers on the extent of data gathering and counseling needed regarding diet, physical activity, and VM supplement use during clinical encounters.
Our study indicates that children and adolescents who may face the greatest risks for VM deficiencies, such as those with less healthy nutrition and activity patterns, greater obesity, lower income, lower food security, poorer health, and lower health care access, use VM supplements the least. There exist multiple competing demands for limited financial resources in families facing financial disparities, and purchasing VM supplements to mitigate the ill effects of a suboptimal diet might not take precedence for such families. Thus, although individuals’ perceptions within the framework of the HBM may play a role in their intentions to use VM supplements, modifying factors, such as financial ability to purchase VM supplements, as depicted in the , may supersede such intentions. We also note that sociodemographic factors influencing VM supplement use are similar to those affecting health behaviors related to maintaining a nutritious diet, greater physical activity, and healthy body weight.
The Health Belief Model as a framework to explain vitamin and mineral (VM) supplement use.
Some children and adolescents who are underweight may potentially benefit from VM supplementation, but for other groups of VM users, medical benefits are less clear. Since VM supplements significantly contribute to total nutrient intakes in children and adolescents, history of their use and reasons for using them should be specifically elicited. Because of greater health care access of VM supplement users, health care providers are well positioned to screen patients regarding nutritional quality of their diet and VM supplement use. Health care providers can then counsel parents that the American Academy of Pediatrics does not recommend use of VM supplements in children and adolescents with varied and healthy diets. It is important to counsel parents of underweight children that use of VM supplements is not a substitute for a physiologically appropriate diet. Our study also suggests that since VM supplements contribute significantly to total dietary intakes of vitamins and minerals, epidemiologic and clinical studies of nutrition should include assessment of VM supplement use. Further qualitative research is needed to explore the relative importance of factors that influence parental decision to use VM supplements for their children, especially in those groups of children who face the highest risks of VM deficiencies.