Methods matter for dietary supplement exposure assessment: comparing prevalence, product types, and amounts of nutrients from dietary supplements in the Interactive Diet and Activity Tracking in the American Association of Retired Persons cohort study.
- Department of Nutrition, Texas A&M University, College Station, TX, United States. Electronic address: alexandra.cowan@ag.tamu.edu.
- Department of Behavioral Sciences and Social Medicine, College of Medicine, Florida State University, Tallahassee, FL, United States.
- NIH Office of Dietary Supplements, Bethesda, MD, United States.
- NIH Office of Dietary Supplements, Bethesda, MD, United States; Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, United States.
- Department of Epidemiology and Prevention, Wake Forest School of Medicine, Wake Forest University, Winston-Salem, NC, United States.
- Department of Statistics, Texas A&M University, College Station, TX, United States.
- Institute for Advancing Health Through Agriculture, Texas A&M AgriLife Research, College Station, TX, United States.
- Department of Biostatistics and Data Science, Wake Forest School of Medicine, Wake Forest University, Winston-Salem, NC, United States.
BACKGROUND: Valid dietary supplement (DS) assessment methods are critical for nutrition research and monitoring as DS contributes substantially toward micronutrient exposures for millions of Americans. Little is known about how DS assessment tools vary in estimating the prevalence of use and micronutrient amounts from DS.
OBJECTIVES: We compared repeat collections over a year of 2 commonly used DS assessment methods: the diet history questionnaire-II (DHQII) and the automated-self-administered 24-h dietary recall (ASA24), within the longitudinal Interactive Diet and Activity Tracking in American Association of Retired Persons (IDATA) study.
METHODS: DS information was collected among IDATA participants (n = 795; 50-74 y) who completed 2-6 ASA24s and a second DHQII. Agreement [Kappa (κ)] at the individual level and group-level prevalence of DS use (McNemar's test) overall and by product type were compared among all participants. Mean calcium and vitamin D intakes, by source, and nutrient amounts per consumption day (i.e., dosages) from DS were compared between the DHQII and ASA24 among DS users. Calcium and vitamin D were chosen as priority nutrients, as they reflect vitamins and minerals and are ubiquitous in DS.
RESULTS: Prevalence of DS use varied by product type [13 of 28 comparisons differed in prevalence (McNemar's test); Kappa agreement range: κ = -0.03 to 0.73)]. Mean consumption day amounts of vitamin D (but not calcium) were remarkably different as assessed by the DHQII and ASA24 (mean ± standard error): vitamin D ranged from 24 ± 2.7 to 45 ± 9.5 μg/d on the ASA24 and from 12 ± 0.3 to 14 ± 0.3 μg/d on the DHQII (P < 0.0001).
CONCLUSIONS: Within IDATA, the comparability of ASA24 and DHQII in estimating the prevalence of use of and nutrient intakes from DS fluctuates by nutrient and product type. DS approaches beyond a questionnaire may be warranted for estimating absolute nutrient amounts, and the choice of the DS assessment method depends on the nutrient/dietary component of interest.