Exploring the Relationship between Dietary Supplement Use and Serum Biomarkers Among Postmenopausal Women in a Controlled Feeding Study

Abstract

Background: Dietary supplement use is common among older adults; however, there remains limited knowledge on the contribution of dietary supplements to the blood profile of nutrient biomarkers. Prior studies have failed to examine these biomarkers of dietary supplement intake under controlled feeding conditions.Objective: This study aimed to determine whether users of dietary supplements had higher serum concentrations of corresponding biomarkers, and whether those using multiple sources of the nutrient in dietary supplement form had higher serum concentrations compared to nonusers and those using only one source. Methods: Postmenopausal women from the Women’s Health Initiative were enrolled in a 2- week feeding study (n = 153). Participants consumed an individualized menu. Detailed information on dietary supplement use was also collected, and participants continued to consume these dietary supplements during the feeding period. Serum vitamin B12, lutein + zeaxanthin, and phospholipid fatty acids (PLFAs) including eicosapentaenoic acid and docosahexaenoic acid were measured at the beginning and end of the 2-week feeding period. Linear regression of dietary supplement use, along with participant characteristics, on log-transformed serum biomarker was used to evaluate the association between dietary supplement use and corresponding serum biomarker. One way ANOVA was used to determine whether there were significant differences in mean serum biomarker among groups based on number of sources of a nutrient consumed via dietary supplement. Results: Linear regression models without participant characteristics (n = 152) showed a positive association between use of vitamin B12 containing dietary supplements, lutein + zeaxanthin containing dietary supplements, and omega-3 fatty acids and respective serum biomarker (p < 0.0001, p = 0.012, and p < 0.0001, respectively). Once additional covariates were included, the positive association remained for vitamin B12 (p < 0.001) and omega-3 fatty acids (p < 0.0001). Users of two sources of a nutrient from a dietary supplement had higher serum biomarkers than users of only a multivitamin and users of neither (p < 0.0001). Conclusions: These results add to the existing body of research on the use of serum vitamin B12 and serum PLFAs as biomarkers of dietary supplement use in postmenopausal women. The relationship between nutrient and biomarker differs for each nutrient studied, and the unique factors impacting these associations should be considered.