Most people love the no-tion of getting all their vitamins and supplements by simply popping a pill. In the US, for example, as many as 53-percent of Americans take a daily multivitamin, driving up the sales of vitamin products to $4.5 billion annually.
In 2009, however, the largest study of its kind concluded that there was no association between multivitamin use and reduced risk of mortality, any type of cancer, or almost any type of cardiovascular disease at least, among postmenopausal women. (However, multivitamins with high doses of folic acid and other B vitamins were linked to a lower risk of heart attack.) Lead author Marian L. Neuhauser, PhD, of the Fred Hutchinson Research Center in Seattle summed up the study’s recommendations bluntly: “Get nutrients from food. Whole foods are better than dietary supplements.”
For most nutrition scientists, such findings are no surprise. In 2006, a 13-member expert panel convened by the US National Institutes of Health (NIH) concluded that there simply wasn’t enough scientific evidence to support recommending the use of multivitamins.
Most recently, in a new consumer advisory on dietary supplements issued by the US Food and Drug Administration (FDA), the agency pointedly omitted multivitamins. The FDA did state that “there are many good reasons” to take individual vitamins or minerals in the right dosages, such as: iron and folic acid for pregnant women, B12 for people over 50 (who may not be able to absorb it from food), and vitamin D for those with darker skin or insufficient exposure to sunlight. The earlier NIH panel likewise cited folic acid in pregnancy and vitamin D, along with calcium, for bone health, plus the antioxidant vitamins shown to prevent age-related macular degeneration (AMD). Those are the only supplement uses, according to experts, that are clearly supported by scientific research rather than marketing hype.
Here are the current scientific facts available on multivitamins and other dietary supplements:
• The claim: Antioxidants help protect cells from the harmful effects of free radicals.
While this claim includes common antioxidant vitamins, multivitamin makers also soup up their products with more exotic antioxidants such as hesperidin complex and quercetin. And the claims for ingredients such as acai berry, grapeseed extract, and various other “botanicals” largely rest on their antioxidant activity.
“Free radicals” are highly reactive atoms or groups of atoms formed in chemical reactions involving oxygen. It’s true that, by definition, antioxidants inhibit the potentially cell-damaging actions of free radicals. But science is still debating how this affects human health and whether “more is better” when it comes to antioxidants. Paul E. Milbury, PhD, author of Understanding the Antioxidant Controversy, cautions, “The research regarding antioxidant mechanism as being the primary beneficial mechanism of the antioxidant vitamins remains theoretical and has not been proven unequivocably in humans.”
Given the plenitude of antioxidants readily available from food where they come packaged with fiber and other nutrients you may not need extra in your multivitamins unless you have a medical condition that requires more than you can get from a healthy diet.
• The claim: Vitamin E “supports heart health.”
Not only is there little evidence for this claim, a widely publicized analysis of data from 19 previous clinical trials found an increased risk of mortality from extra vitamin E. The study found that among those taking more than 400 IU of vitamin E daily, there were 39 additional deaths per 100,000 people. A similar analysis by the US Agency for Healthcare Research and Quality (AHRQ) concluded, “There is little evidence that vitamin E supplementation results in a reduction in cardiovascular mortality.”
Most recently, the Physician’s Health Study II, which tested the daily intake of 400 IU of vitamin E among 14,641 men over age 50, concluded: “These data provide no support for the use of these supplements for the prevention of cardiovascular disease in middle-aged and older men.”
Vitamin E showed no effect on the incidence of major cardiovascular events, heart attack or cardiovascular mortality, and actually increased hemorrhagic stroke compared to placebo.
• The claim: Omega 3s/fish oil is good for heart health and “mental and visual functioning.”
There’s strong evidence that omega-3 fatty acids from fish oil have cardiovascular benefits, and some studies have suggested omega-3s may also help protect the aging brain and prevent AMD. So the question is not whether omega-3s are good for you, but whether the amount you take is enough to make such products worth seeking out.
Three ounces of cooked salmon contain about 1.8 grams of the two most important omega-3s found in fish: DHA and EPA. Some vitamin-fish oil combinations contain just 0.5 milligrams of omega-3s or less than 1/3000th the amount in a serving of salmon.
• The claim: Ginseng helps improve physical and mental performance, increasing resistance to stressful conditions.
Although more study is needed, ginseng has been found to be potentially beneficial for a wide range of conditions, including heart disease, high blood sugar, and diabetes. The evidence remains unclear, however, for other claims, including effects on dementia, fatigue, mental performance, and overall well-being, according to NIH and NLM (National Library of Medicine). Doses in studies that have shown ginseng benefits range from 100 to 400 milligrams daily.
• The claim: Extra B vitamins help convert food into energy.
It’s true that B vitamins help unlock the energy in foods, but you’re probably already getting plenty of these vitamins in your diet. The added B vitamins in many multivitamins mostly just get flushed out of your system. Too much B6 can cause nerve damage, according to the US Institute of Medicine, but the danger level is about 50 times the DV (Daily Values).
As the US FDA noted, older people sometimes do lose some of the body’s natural ability to absorb vitamin B12 from food. According to the US NIH/NLM, “Because 10 percent to 30 percent of older people do not absorb food-bound vitamin B12 efficiently, those over 50 years of age should meet the RDA (Recommended Daily Allowance) by eating foods fortified with B12 supplement. Supplementation of 25-100 micrograms per day has been used to maintain vitamin B12 levels in older people.
• The claim: Ginkgo biloba boosts memory and concentration.
The longest prevention trial to date of ginkgo biloba has failed to show any benefit from this herb in reducing the risk of dementia or Alzheimer’s disease. The Ginkgo Evaluation of Memory (GEM) study was a six-year randomized, placebo-controlled clinical trial considered the gold standard of medical research of 3,069 volunteers age 75 or older. Researchers concluded, “Based on the results of this trial, ginkgo biloba cannot be recommended for the purpose of preventing dementia.” An accompanying editorial added, “The GEM study adds to the substantial body of evidence that ginkgo biloba extract, as it is generally used, does not prevent dementia in individuals with or without cognitive impairment and is not effective for Alzheimer’s disease.”
• The claim: Probiotics improves digestion.
Bacteria such as Lactobacillus acidophilus live naturally in the human digestive system, where they produce vitamin K, lactase, and various anti-microbial substances. The idea of giving your digestive bacteria some reinforcements has become popular in food products and even in some multivitamins. But such “probiotic” uses of acidophilus are not yet sufficiently studied to be able to form clear conclusions, according to the NIH/NLM.
A 2005 report from a conference co-sponsored by the National Center for Complementary and Alternative Medicine (NCCAM) was more positive, citing “encouraging evidence” that specific probiotic formulations might be useful to treat diarrhea (specially from rotovirus), irritable bowel syndrome (IBS), and intestinal infections.
The bottomline: The jury is still out on this one.