Multivitamin Use and Risk of Cancer and Cardiovascular Disease in the Women's Health Initiative Cohorts

Abstract

Context Millions of postmenopausal women use multivitamins, often believing that supplements prevent chronic diseases such as cancer and cardiovascular disease. Objective To examine associations between multivitamin use and risk of cancer, cardiovascular disease and mortality in postmenopausal women. Design, Setting and Participants 161,808 participants from the Women’s Health Initiative Clinical Trials (n=68,132 in three overlapping trials of hormone therapy, dietary modification and calcium-vitamin D) or Observational Study (n=93,676). Detailed data were collected on multivitamin use at baseline and follow-up time points. Study enrollment occurred between 1993–1998; women were followed for a median of 8.0 years in the clinical trials and 7.9 years in the observational study. Disease endpoints were collected through 2005. Outcome Measures Cancers of the breast (invasive), colon/rectum, endometrium, kidney, bladder, stomach, ovary and lung; cardiovascular disease (myocardial infarction, stroke, venous thrombosis); and total mortality. Results 41.5% of participants used multivitamins. After a median of 8.0 years of follow-up in the CT and 7.9 years in the OS, 9,619 cases of breast, colorectal, endometrium, kidney, bladder, stomach lung or ovary cancer; 8,751 CVD events and 9,865 deaths were reported. Multivariate-adjusted analyses revealed no association of multivitamins with risk of cancer (breast HR=0.98, 95%CI 0.91–1.05; colorectal HR = 0.99, 95% CI 0.88–1.11; endometrial HR = 1.05, 95%CI= 0.90–1.21; lung HR = 1.0, 95% CI=0.88–1.13; ovary HR = 1.07, 95%CI =0.88–1.29); CVD (MI HR= 0.96, 95%CI= 0.89–1.03; stroke HR = 0.99, 95%CI =0.91–1.07; VT HR = 1.05, 95%CI =0.85–1.29); or mortality (HR = 1.02, 95% CI=0.97–1.07). Conclusion After a median follow-up of 8.0 and 7.9 years in the CT and OS, respectively, the WHI cohorts provide convincing evidence that multivitamin use has little or no influence on the risk of common cancers, cardiovascular disease or total mortality in postmenopausal women. Clinical Trial Registration clinicaltrials.gov identifier: NCT00000611

Dietary supplement use and colorectal cancer risk: A systematic review and meta‐analyses of prospective cohort studies

“…[26][27][28][29][30][31] No heterogeneity was detected (I 2 5 4.9%, p 5 0.39). The current analysis includes five out of 13 cohorts from the Pooling Project, 21 while three cohorts of our analysis were not included in the pooled analyses.…”

“…Finally, most of the studies reported on multivitamin use in general. [26][27][28]30,31 However, the composition of the multivitamins in those studies is unclear as the authors did not further specify whether the supplements contained vitamins only, or also included minerals. The study of Park et al 31 described that their questionnaire included questions about the use of multivitamins (with or without minerals), but in their analyses it was not clear which type of multivitamins, that is, with or without minerals, they had studied.…”

“…Second, most studies failed to account for duration of supplement use. For instance, in the Health Professionals Follow-Up study and the Nurses' Health Study 36 dietary supplement use was defined as "current use during the past year," while in the Womens' Health Study 28 use was described as "use of any supplement at least once a week." Given that colorectal cancer has a long induction and latent period, it should have been appropriate if studies accounted for days per week the supplement was taken, and for years of supplement use.…”

Vitamins, Are They Safe?

“…However, several studies could not find significant effectiveness of vitamin E on prevention of cancer, 4,7-25 reduction in cardiovascular diseases, 8,13,25-36 and overall mortality reduction. 5,15,19,25,27,[37][38][39] In a randomized, double-blind, placebo-controlled trial (The Physicians' Health Study II), a total of 14641 male physicians aging more than 50 years were enrolled. They received supplements of vitamin E (400 IU) every other day and were followed for 8 years.…”

Complementary and alternative medicine: Herbals and supplements: A review for the primary care physician

“…Regular multivitamin pills differ from mega vitamins in the sense that the latter refers to high doses of vitamins as compared to standard multivitamin pills. The Women's Health Initiative study has shown no link between multivitamin supplementation and risk of lung cancer, colorectal cancer, breast cancer, endometrial cancer, ovarian cancer, and cardiovascular and total mortality in postmenopausal women [128]. The Iowa Women's Health Study of 38,772 older women confirmed that many commonly used dietary vitamin and mineral supplements may be associated with increased total mortality risk; the association was strongest with iron, while calcium was associated with diminished risk [129].…”