In the US, the use of dietary supplements has increased substantially during the past several decades. Approximately one-half of adults in 2000 were using supplements, and contributed to the annual sales of more than $20 billion. Despite the mounting evidence that shows the ineffectiveness of supplementation to prevent chronic diseases, the multivitamin and supplement industry continues to grow. And what if you knew they could be causing you harm?
In a large, longitudinal Women’s Health Study, 66% of women participating used at least 1 dietary supplement daily in 1986 at an average age of 62 years. By 2004, that proportion increased to 85%, and 27% of those women reported using 4 or more supplemental products. That’s a lot of supplementing (and money), but why?
Supplemental nutrient intake clearly is beneficial in deficiency conditions and with folic acid during pregnancy. However, in well-nourished populations, supplements fail to yield any benefits for preventing chronic diseases. Several well-designed trials concentrating mainly on calcium and vitamins B, C, D, and E, have not shown beneficial effects of dietary supplements on total mortality rate. Findings published by Annals of Internal Medicine found long-term multivitamin supplementation does not provide cognitive benefits and high-dose oral multivitamins and multiminerals do not reduce cardiovascular events. This reinforces the recommendation from the US Preventive Services Task Force (USPSTF), that the current evidence is insufficient to assess the balance of benefits and harms of the use of multivitamins, vitamin, and mineral supplementation for the prevention of cardiovascular disease or cancer.
The Journal of American Medical Association (JAMA) presents similar articles and research on supplementation, but also draws attention that multivitamins might even be harmful. In older women, especially, several commonly used dietary vitamin and mineral supplements may be associated with increased total mortality risk. Recent data reported in the Cochrane Collaboration suggested that beta carotene and vitamin E seem to increase mortality, and so may higher doses of vitamin A. This is consistent with the USPSTF, that recommends against the use of β-carotene or vitamin E supplements for the prevention of cardiovascular disease or cancer.
A conclusive summary from the research article “Enough is enough:Stop Wasting Money on Vitamin and Mineral Supplements“, “β-carotene, vitamin E, and possibly high doses of vitamin A supplements are harmful. Other antioxidants, folic acid and B vitamins, and multivitamin and mineral supplements are ineffective for preventing mortality or morbidity due to major chronic diseases. Although available evidence does not rule out small benefits or harms or large benefits or harms in a small subgroup of the population, we believe that the case is closed— supplementing the diet of well-nourished adults with (most) mineral or vitamin supplements has no clear benefit and might even be harmful. These vitamins should not be used for chronic disease prevention.”
So if the largely unregulated market of multivitamins – whether in pill, powder, or liquid form – are not beneficial and may even be harmful, why continue to spend money on them?