Dietary supplement use is associated with lower mortality risk in U.S. adults diagnosed with cancer.

BACKGROUND: The increasing usage of dietary supplements raises questions about their impact on mortality outcomes in cancer survivors, yet the evidence remains controversial. In a large population-based cohort of cancer survivors, this study examined the correlation between dietary supplement use and mortality risk. METHODS: This observational study analyzed data from the National Health and Nutrition Examination Survey (NHANES), focusing on adults with diagnosed cancer who completed dietary supplement questionnaires. Cox proportional hazard models were used to analyze all-cause mortality and competing risk analyses were performed to assess for cause-specific mortality. Analyses were conducted for supplement use adjusted for demographic, lifestyle and clinical characteristics. RESULTS: This study included 2,494 adults with a history of cancer, of whom 1,571 (62.99%) reported regular supplements use. The most commonly used supplements were vitamins (92.04%), minerals (79.19%), and botanicals (17.95%). A median follow-up of 6.58 years revealed 542 fatalities from all causes. In the fully adjusted model, overall supplement use was inversely associated with cancer mortality (HR = 0.60, 95% CI: 0.42-0.87, P = 0.007). Exploratory analyses by supplement ingredient category showed inverse associations of vitamin use (HR = 0.60, 95% CI: 0.42-0.85, P = 0.005) and mineral use (HR = 0.69, 95% CI: 0.51-0.94, P = 0.02) with cancer mortality, and of botanical use with all-cause mortality (HR = 0.71, 95% CI: 0.53-0.97, P = 0.03). CONCLUSIONS: Dietary supplement use was associated with lower cancer mortality among U.S. adults with a history of cancer. These observational findings may inform prospective studies and randomized clinical trials evaluating the clinical implications of specific supplement regimens in cancer populations.