Emerging Patterns in Dietary Supplement Use Among US Adults, 1999-2023.

Importance: Dietary supplement use is widespread among US adults, but long-term national data, particularly on emerging products and COVID-19-related changes, are limited. Understanding population-level changes is essential to inform research and public health priorities. Objective: To evaluate 25-year trends in dietary supplement use among US adults. Design, Setting, and Participants: This study is a cross-sectional analysis of 11 cycles of the National Health and Nutrition Examination Survey (NHANES), a nationally representative survey, from 1999 to 2000 through August 2023. Participants were civilian, noninstitutionalized US adults (aged ≥20 years) who completed supplement use interviews. Exposures: Calendar time represented by cycle. Main Outcomes and Measures: The prevalence of supplement use in the past 30 days was assessed overall, by category (vitamins, minerals, multivitamin-multimineral [MVMM], and nonvitamin nonmineral [NVNM]), and by supplements. Trends were evaluated across cycles and by subgroups (age, sex, race and ethnicity, education, and income-to-poverty ratio). Prepandemic and early-pandemic (2017 to March 2020) and later-pandemic and postpandemic (August 2021 to August 2023) periods were compared. Survey-weighted binomial regression models were used to estimate linear trends across cycles. Results: This nationally representative study included 63 442 adults (weighted mean [SD] age, 47.3 [17.0] years; 33 127 women [52%]). Overall supplement use increased from 51% (95% CI, 49%-54%) in 1999 to 2000 to 60% (95% CI, 57%-63%) in August 2021 to August 2023 (P for trend, <.001), driven largely by increases after 2009 to 2010. MVMM use decreased (from 35% [95% CI, 33%-37%] to 31% [95% CI, 29%-34%]); in contrast, use of vitamins (from 25% [95% CI, 23%-28%] to 39% [95% CI, 37%-41%]), minerals (from 18% [95% CI, 16%-19%] to 27% [95% CI, 24%-30%]), and botanicals (from 11% [95% CI, 9.2%-12%] to 13% [95% CI, 12%-15%]) outside of MVMM increased. Notable increases were observed for vitamins and minerals outside MVMM, including vitamin D, vitamin K, zinc, and turmeric and curcumin, and for NVNM with emerging use in later cycles, such as ashwagandha, hyaluronic acid, elderberry, collagen, and prebiotics or probiotics. Notable declines occurred for trace minerals and several botanicals (eg, ephedra or ginseng). Supplement use increased most among adults aged 65 years and older (from 62% [95% CI, 58%-65%] to 78% [95% CI, 75%-81%]) and was highest in that group vs the other age groups. Vitamins, minerals, and some NVNM supplement use increased in the late-pandemic or postpandemic period compared with prepandemic or early-pandemic period, notably in products marketed for immune health (eg, zinc and elderberry). Conclusions and Relevance: In this repeated cross-sectional analysis of NHANES 1999 to 2023, supplement use among US adults increased over time, with diversification beyond MVMMs toward products marketed for immune, anti-inflammatory, gut, skin, or joint health. A substantial increase was observed in older adults. Ongoing monitoring of supplement use trends is needed to understand evolving public health implications.