Multivitamins in the prevention of cancer and cardiovascular disease: the COcoa Supplement and Multivitamin Outcomes Study (COSMOS) randomized clinical trial.
Level 2 - randomized trial
Randomized, double-blind, placebo-controlled trial
PubMed 35294969 · doi:10.1093/ajcn/nqac056
What was done
A randomized, double-blind, placebo-controlled, 2-by-2 factorial trial (COSMOS) evaluated daily multivitamin-multimineral (MVM) supplementation versus placebo for the prevention of cancer and cardiovascular disease (CVD) among 21,442 US adults (12,666 women aged ≥65 years and 8,776 men aged ≥60 years) free of major CVD and recently diagnosed cancer. The intervention ran from June 2015 to December 2020. The primary outcome was total invasive cancer (excluding nonmelanoma skin cancer). Secondary outcomes included major site-specific cancers, total CVD, all-cause mortality, and total cancer risk among those with a baseline history of cancer.
What was found
Over a median follow-up of 3.6 years: - Total invasive cancer: 518 in MVM group vs 535 in placebo group (HR: 0.97; 95% CI: 0.86, 1.09; P = 0.57). - Site-specific cancers: breast cancer HR 1.06 (95% CI: 0.79, 1.42); colorectal cancer HR 1.30 (95% CI: 0.80, 2.12); lung cancer HR 0.62 (95% CI: 0.42, 0.92). - Composite CVD outcome: 429 in MVM group vs 437 in placebo group (HR: 0.98; 95% CI: 0.86, 1.12). - All-cause mortality: HR 0.93 (95% CI: 0.81, 1.08). - No safety concerns were observed.
Why it matters
In a large, randomized cohort of older adults, daily multivitamin use did not lower total cancer incidence, cardiovascular events, or all-cause mortality over 3.6 years. These findings do not support routine multivitamin supplementation for primary prevention of major chronic diseases.
Limits
The median follow-up of 3.6 years may be too short to detect effects on cancers with long induction or latency periods. The study was limited to US older adults (women ≥65, men ≥60) without recent major CVD or cancer, which may not generalize to younger or nutritionally deficient populations. The observed lung cancer reduction was a secondary outcome and could represent a chance finding due to multiple testing. Dietary baseline status and adherence details were not provided in the abstract.
Cited by
- supports In the main COSMOS randomized controlled trial, multivitamin supplementation showed no statistically significant reduction in hard clinical endpoints like all-cause mortality, cancer mortality, or cardiovascular disease.