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Many people take vitamin and mineral supplements in hopes of reducing their risk for heart disease, cancer and other degenerative diseases, and some research does supports those hopes. But several recent large long-term studies have found that supplements work no better than placebos.



Ever since the Nobel Prize-winning biochemist Linus Pauling first promoted “megadoses” of essential nutrients 40 years ago, Americans have been devoted to their vitamins. Today about half of all adults use some form of dietary supplement, at a cost of $23 billion a year.



But are vitamins worth it? Recently several high-quality studies have failed to show that extra vitamins, at least in pill form, help prevent chronic disease or prolong life.



The most recent news came earlier this year after researchers in the Women’s Health Initiative study tracked eight years of multivitamin use among more than 161,000 older women. Despite earlier findings suggesting that multivitamins might lower the risk for heart disease and certain cancers, the study, published in The Archives of Internal Medicine, found no such benefit.



Last year, a study that tracked almost 15,000 male physicians for a decade reported no differences in cancer or heart disease rates among those using vitamins E and C compared with those taking a placebo. And in October, a study of 35,000 men dashed hopes that high doses of vitamin E and selenium could lower the risk of prostate cancer.





Everyone needs vitamins, which are essential nutrients that the body can’t produce on its own. Inadequate vitamin C leads to scurvy, for instance, and a lack of vitamin D can cause rickets.



Most major vitamin studies in recent years, however, have not focused on deficiencies but on whether high doses of vitamins can prevent or treat a host of chronic illnesses. While people who eat lots of nutrient-rich fruits and vegetables have long been known to have lower rates of heart disease and cancer, it hasn’t been clear whether ingesting high doses of nutrients in pill form results in a similar benefit.



In January, an editorial in The Journal of the National Cancer Institute noted that most trials had shown no cancer benefits from vitamins — with a few exceptions, like a finding that calcium appeared to lower the recurrence of precancerous colon polyps by 15 percent.



But some vitamin studies have also shown unexpected harm, like higher lung cancer rates in two studies of beta carotene use. Another study suggested a higher risk of precancerous polyps among users of folic acid compared with those in a placebo group.



In 2007, The Journal of the American Medical Association reviewed mortality rates in randomized trials of antioxidant supplements. In 47 trials of 181,000 participants, the rate was 5 percent higher among the antioxidant users. The main culprits were vitamin A, beta carotene, and vitamin E. Vitamin C and selenium seemed to have no meaningful effect.



“We call them essential nutrients because they are,” said Marian L. Neuhouser, an associate member in cancer prevention at the Fred Hutchinson Cancer Research Center in Seattle. “But there has been a leap into thinking that vitamins and minerals can prevent anything from fatigue to cancer to Alzheimer’s. That’s where the Science didn’t pan out.”



Everyone is struggling to make sense of the conflicting data, said Andrew Shao, vice president for scientific and regulatory affairs at the Council for Responsible Nutrition, a vitamin industry trade group. Consumers and researchers need to “redefine our expectations for these nutrients,” he said. “They aren’t magic bullets.”



Part of the problem, he said, may stem from an inherent flaw in the way vitamins are studied. With drugs, the gold standard for research is a randomized clinical trial in which some patients take a drug and others a placebo. But vitamins are essential nutrients that people ingest in their daily diets; there is no way to withhold them altogether from research subjects.



The selling point of antioxidant vitamins is that they mop up free radicals, the damaging molecular fragments linked to aging and disease. But some free radicals are essential to proper immune function, and wiping them out may inadvertently cause harm.



“Most antioxidants are also pro-oxidants,” said Dr. Peter H. Gann, professor and director of research in the department of pathology at the University of Illinois at Chicago. “In the right context and the right dose, they may be able to cause problems rather than prevent them.”



Scientists suspect that the benefits of a healthful diet come from eating the whole fruit or vegetable, not just the individual vitamins found in them. “There may not be a single component of broccoli or green leafy vegetables that is responsible for the health benefits,” Dr. Gann said. “Why are we taking a reductionist approach and plucking out one or two chemicals given in isolation?”



We know that vitamins are essential to good health and can prevent disease. We also know that vitamin supplementation is useful in preventing and treating numerous diseases. The real question is: How beneficial are vitamin supplements in preventing chronic conditions like heart disease and cancer?



Study after study has demonstrated the benefit of whole foods, rich in vitamins and minerals in preventing disease, including those of the heart and





circulatory system. Supplements, however, may not be as good as real food. One of the problems with dietary supplements is that they often contain synthetic vitamins which are not the same as natural vitamins. Although they may look similar and have similar physiological effects, they are not identical. Therefore, their effects are not identical. So the synthetic vitamins may be less effective at protecting against certain health conditions.



Processed foods are not a good source of vitamins and minerals even if they are "fortified."

Another shortcoming with synthetic vitamins is that they are isolated nutrients. Vitamins in foods are never isolated, but occur with dozens, if not hundreds of other vitamins, minerals, and nutrients. All of which, work synergistically together. For example, vitamin E is not simply one vitamin, but consists of a family of eight vitamins. Dietary supplements usually contain only one form of vitamin E. Foods, however, contain mixtures of all eight forms. While each form of vitamin E is similar in structure, they each have their own characteristics and affect the body differently. Each of these forms of vitamin E provides benefit. When combined they provide the greatest protection against heart disease and other conditions. But when isolated, that protection may seriously decline or even disappear. The same is true with vitamin C. In nature vitamin C is always associated with bioflavonoids. They work synergistically together. It is no wonder then, when studies use isolated nutrients the results are unimpressive. Foods contain hundreds of nutrients that work together for your health. Dietary supplements contain only a few.



Some vitamins may become toxic when taken in isolation from other nutrients. For example, vitamin D, an essential nutrient, can become toxic at high doses. But when combined with vitamin A, the toxicity level plumpest rapidly. Vitamins D and A work synergistically together to provide many health benefits’ but too much of one without the other can lead to problems. This may explain why some studies have shown detrimental effects with large doses of beta-carotene and vitamin A. This is only seen in dietary supplements. Vitamins from whole foods do not cause these problems.



What we can learn from these studies is that eating isolated nutrients does not guarantee good health. Many people tend to think that if they take a vitamin and mineral supplement that it gives them an excuse to make poor eating choices. It doesn’t. Eating a bowl of Lucky Charms breakfast cereal, which is fortified with several vitamins and minerals, is not a nutritious breakfast! Likewise, white “enriched” bread is not the same as eating whole wheat bread. Vitamins don’t make up for a poor diet or for highly processed, nutrient deficient foods. Dietary supplements are just that—supplements, not food. The only way you can get all the protective vitamins and minerals you need to be healthy, is from real foods.







References:



Sesso, H.D., et al. Vitamins E and C in the prevention of cardiovascular disease in men: the Physicians’ Health Study II randomized controlled trial. JAMA. 2008;300(18):2123-2133.





Lippman, S.M., et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers. JAMA. 2009;301(1):39-51.





Neuhouser, M.L. Multivitamin use and risk kof cancer and cardiovascular disease in Woman’s Health Initiative cohorts. Arch Intern Med. 2009;169(3):294-304.





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