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Vitamin Supplements: The Dilemma

Jul 24, 2014 10:05AM ● By Cate Reynolds
By Lisa A. Lewis

When an editorial entitled “Enough is Enough: Stop Wasting Money on Vitamin and Mineral Supplements” was published in the Annals of Internal Medicine (AIM) in December 2013, the authors attempted to end the ongoing debate over the efficacy of vitamin and mineral supplementation. Instead, their conclusion 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” revived an issue that has already been the source of numerous studies.

Indeed, disagreement over the effectiveness of supplements has persisted for years. However, the issue has taken on a new dynamic as more and more products are introduced to store shelves. Products that were once marketed to fulfill nutritional requirements are now touted as a panacea—boasting claims such as disease prevention and targeting concerns such as heart, breast, prostate, and eye health. Deciding which—if any—supplements to take can be overwhelming. More important, however, is the age-old question of whether or not vitamin and mineral supplements deliver on the claims they make on their labels.

No Benefits? Possible Harm?

To clarify misconceptions about supplements, the authors of the editorial reported on the findings of three studies that evaluated the role of vitamin and mineral supplements with regard to chronic disease prevention, cognitive function, and heart health. In the first study, which reviewed three trials of multivitamin supplements and 24 trials of vitamins among more than 400,000 participants, researchers found no evidence that supplements prevent chronic disease, such as cancer. The second study evaluated the effect of a multivitamin on cognitive function among 5,947 men aged 65 years and older. After a 12-year randomized, placebo-controlled trial (a study in which people are assigned at random to receive either the supplement or a placebo), researchers found that multivitamins didn’t prevent cognitive decline. The role of high-dose multivitamins in preventing a heart attack in 1,708 men and women with a history of a previous heart attack was the focus of the third study. In a five-year randomized, placebo-controlled trial, researchers found no difference in recurrent cardiovascular events with multivitamins compared to placebos.

Based on the findings of these studies, the authors of the editorial concluded that the use of supplements isn’t justified and advised consumers not to take them.

“Evidence is sufficient to advise against routine supplementation,” the authors say. “This message is especially true for the general population with no clear evidence of micronutrient deficiencies, who represent most supplement users in the United States.”

“There are a few people in the United States who have particular nutritional deficiencies,” adds Cynthia Mulrow, M.D., senior deputy editor of Annals of Internal Medicine and one of the authors of the editorial. “They can be treated with specific supplements targeted toward their deficiency. However, the majority of Americans don’t fi t into this category.” Interestingly, in addition to no benefit, studies reveal evidence of possible harm from certain supplements, including beta-carotene, vitamin A, and vitamin E. According to Mulrow: several studies suggest beta-carotene increases the risk for lung cancer in some high-risk individuals; a possible increased mortality risk has been associated with high doses of vitamin A, and studies suggest that vitamin E doesn’t reduce the incidence of heart attacks—as once thought—and may increase mortality risk.

And these findings aren’t new: Previous studies have yielded similar results. A January 2009 editorial in The Journal of the National Cancer Institute cited two studies that indicated higher rates of lung cancer in participants who were taking beta-carotene. In 2007, The Journal of the American Medical Association reviewed mortality rates in randomized trials of antioxidant supplements. In 47 trials of 180,938 participants, researchers found that beta-carotene, vitamin A; and vitamin E may increase mortality. These findings are noteworthy because they indicate evidence of harm associated with particular supplements that has been replicated in more recent studies.

Further Studies

According to the National Cancer Institute, in 2008, after a five-and-a-half year randomized, placebo-controlled trial of 35,533 men aged 50 and older, researchers found that high doses of selenium and vitamin E, taken alone or in combination, didn’t prevent prostate cancer, so the study was discontinued. However, in 2011, researchers found evidence of unexpected harm: Updated data indicated that men taking vitamin E had a 17 percent increased risk of prostate cancer compared to men taking the placebo.

Americans, however, haven’t stopped taking their vitamins. The authors of the AIM editorial indicate that the use of multivitamin supplements increased among U.S. adults from 30 percent between 1988 and 1994 to 39 percent between 2003 and 2006, and overall use of dietary supplements increased from 42 percent to 53 percent. In addition, the authors report that the U.S. supplement industry continues to grow, reaching $28 billion in annual sales in 2010.


A Caveat

The benefits of receiving nutrition through our food is obvious. Given the high carb, high sugar American diet, however, it may be impractical. What’s better, not eating well and not taking vitamins, or not eating well and receiving some form of nutrition from pills? Judicious use of those pills would seem to be a logical reaction. There is also the legitimate medical use of high dosage therapies. In a lengthy evidenced-based monograph prepared by the Natural Stand Research Collaboration and published by the Mayo Clinic on their website, the therapeutic practice of administering vitamin D in high doses is explored. The common use of vitamin D in larger-than-multivitamin doses to treat such conditions as heart disease, atopic eczema, cystic fibrosis, osteoporosis, and arthritis is not challenged. That may well be because vitamin D isn’t all that easy to acquire through nature—it’s found in very small amounts in foods and many of us want to avoid the sun. It’s an ideal example of the prudent use of vitamin supplements.—S.H.