One of the greatest triumphs of marketing over evidence was the incredible rise of vitamin supplement use in the 20th century. Supplement makers successfully created a “health halo” around vitamins, and taking your vitamins became a virtue, something mothers told their children to do. The evidence, however, does not tell such a simple story.
In recent years it has become increasingly apparent that there are unintended consequences to taking vitamin supplements, and in fact there may be a net negative health effect. This is especially true for those who are healthy and don’t need vitamins, and for those who exceed the recommend dosages.
A recent review of the last 20 years of literature on the subject, presented at the American Association for Cancer Research 2015 meeting, found an overall increased risk of cancer among vitamin users. Dr. Tim Byers presented the study, which echoes the result of a 2012 review that he and others published. He specifically refers to two famous studies showing an increased risk of cancer from vitamins.
The 2011 SELECT trial found an overall increased risk of prostate cancer among men taking vitamin E. (more…)
Multivitamin supplementation has been getting a rough ride in the literature, as evidence emerges that routine supplementation for most is, at best, unnecessary. Some individual vitamins are earning their own unattractive risk/benefit profiles: Products like folic acid, calcium, and beta-carotene all seem inadvisable for routine supplementation in the absence of deficiency or medical indication. Vitamin E, already on the watch list, looks increasingly problematic, with data recently published confirming the suspected association of supplementation with an elevated risk of prostate cancer.
Reading through the vitamin posts here at SBM, one issue comes through repeatedly: The danger of assuming therapeutic benefits in the absence of confirmatory evidence. Vitamin supplement have the patina of safety and of health, a feature that’s reinforced when you purchase them: You don’t need a prescription, you don’t get counseled on their use, and there isn’t a long list of frightening potential side effects to accompany the product. You can pull a bottle off the shelf, and take any dose you want. After all, how harmful can vitamins be when you can buy 5 pounds of vitamin C at a time, or vitamin E capsules in a 1000-pack? But the research signals seem to be getting stronger, and most are pointing in the same direction: what we though we knew about antioxidants was based on simplistic hypotheses about nutrition and health. And while we thought we were doing ourselves good with antioxidant supplements, we may have been doing harm. (more…)
I’ll start with a confession. I used to do something irrational. I used to take a daily multivitamin, not because I thought there was good scientific evidence to support the practice, but for psychotherapy. I tried to eat a healthy diet and worried about it. By taking a pill, I could stop worrying.
Then I found out that higher intake of vitamin A was associated with an increased risk of hip fractures in postmenopausal women like me, and I stopped. (High doses of vitamin A also cause births defects and are contraindicated in pregnancy.) Now I only take supplemental calcium and vitamin D, not on general principles but because of personal risk factors.
We’re being bombarded by advice to take vitamins and various other supplements. Health gurus like Andrew Weil recommend that everyone take vitamins (which they just happen to sell). The orthomolecular followers of Linus Pauling want us to take megadoses of vitamins. Ray Kurzweil tells us we should take vitamins to make us live longer; he takes 250 vitamin and supplement pills a day and thinks he will live forever. (You can read about his ideas in his book Fantastic Voyage: Live Long Enough to Live Forever.) Who should we believe? (more…)