The Women’s Health Initiative (WHI), a long-term study of over 160,000 postmenopausal women, just published its findings on the use of multivitamins. The results showed that there was simply no benefit (nor any apparent harm) in these older women from regular vitamin supplementation whether to reduce overall mortality, heart disease or stroke, or a wide variety of common cancers. The findings were just published in the Archives of Internal Medicine, Feb 9, 2009 (Multivitamin Use and Rick of Cancer and Cardiovascular Disease in the Women’s Health Initiative Cohorts).
The WHI reviewed data over about 8 years on the 160,000 participants. All were women about 50 or older. About 41% used multivitamins, largely standard preparations or with minerals, a few used “stress” vitamins. The death rates and incidence of heart attacks, strokes, blood clots and a wide variety of cancers (breast, colon, lung, ovarian, endometrial, kidney, bladder, stomach) were unchanged. No benefit was seen, but also no harm (which has been seen with high-dose supplementation of certain vitamins, such as Vitamin E and carotene).
These results apply to postmenopausal women, and most likely apply to older men as well, as guidance about looking to vitamin supplementation to prevent disease and death. But vitamin deficiency does occur, and there are circumstances where regular multivitamins are helpful and recommended.
For example, multivitamin supplementation is appropriate for those who do not reasonably regularly eat a well-distributed diet that includes green vegetables, salads, fruits, and some dairy products. It is also appropriate for young women who may become pregnant, since adequate folic acid and B-12 are needed to prevent certain birth defects.
And there is some possibility from this study that the stress vitamins may minimally reduce heart problems in older women, but the data supporting that inference were barely statistically significant and don’t gibe with lack of benefit for other types of cardiovascular disease, so I hardly find the results compelling.
Multivitamin supplementation in older women has essentially no impact on heart disease or stroke, major cancers, or lifespan. There is no benefit nor apparent harm. These findings most likely apply to older men, but the WHI only studied women. However, vitamin supplementation has important uses to prevent deficiency states in persons with poor nutrition and especially in pregnant women.