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QUESTION: I eat pretty healthful, balanced meals. Do I still need a multivitamin and mineral supplement?


ANSWER: Here’s the bottom line. Most people who are healthy and eat healthily don’t need a daily multivitamin and mineral supplement. They don’t need individual vitamin or mineral supplements, either. According to the Dietary Guidelines for Americans, most children older than nine and adults who eat sufficient amounts of nutrient-dense foods (that’s mainly fruits, vegetables, whole grains, legumes/beans, low-fat dairy foods) and consume at least 6 700 kilojoules can meet their nutrition needs from foods.

Yes, this sounds like heresy or, at best, counterintuitive to consumers faced with the marketing prowess of the dietary supplement industry. But the mantra, “if a small amount is good for you, then more must be better” hasn’t, according to research, been wise advice.

Over the past couple of decades, one study after another has set out to research the health effects of large doses of vitamins or minerals, particularly antioxidants. And they’ve found no significant benefits. Worse yet, some have uncovered health concerns, such as increased risk of heart disease or cancer.

An explanation? “Oxidation, the process by which the body uses oxygen to convert food to energy, creates free radicals, often billed as evil-doers in our bodies,” says Paul Offit, chief of the division of infectious diseases at the Children’s Hospital of Philadelphia and author of Do You Believe In Magic? The Sense And Nonsense Of Alternative Medicine.

Those free radicals can damage cells and the lining of arteries, one reason they’ve been linked with ageing, certain cancers and heart disease.

But, Offit says, we’ve discovered we need free radicals to kill bacteria and cancer cells. When people take large doses of antioxidants (such as selenium, beta-carotene, and vitamins A, C and E), “they can tip the balance towards an unnatural state in which the immune system is less able to kill harmful invaders”.

A study this year in the Journal of American Medical Association Internal Medicine analysed the use of supplements among a large sample of American adults.

“We found half of US adults use dietary supplements, most commonly a multivitamin and mineral supplement,” says the lead author, Regan Bailey, a dietitian and nutritional epidemiologist in the Office of Dietary Supplements at the National Institutes of Health.

Bailey adds: “Our study reveals that adults use supplements primarily for their assumed health benefits, yet there remains a lack of sufficient research on this.”

Interestingly and somewhat predictably, Bailey’s research showed that the adults studied tended to report eating more healthily, practising moderation with alcohol, exercising and abstaining from smoking.

Another important concern raised by Bailey’s study is only a quarter of the supplements taken by adults were recommended by their health-care provider.

This can be dangerous because of potential interactions of supplements, prescribed medications and other therapies. Your health-care provider should be asking about your supplement use, but if they don’t, bring it up.

Bailey and Offit agree most people who are healthy and eat healthily don’t supplementation.

Offit’s suggestion: start by eating sufficient fruits and vegetables. They’re low in kilojoules and packed with nutrients.

The Academy of Nutrition and Dietetics concurs with this food-first approach.

However, the academy and experts agree on this important caveat: some people, based on their nutrition intake, medical issues and other circumstances, may need to fill nutrition gaps with supplements. Consider women of childbearing years, women who are pregnant, people who are vegan or strict vegetarians and people who don’t consume sufficient kilojoules, to name a few.

When it comes to choosing the foods you eat, make your kilojoules count. – Washington Post-Bloomberg


* Warshaw, a registered dietitian nutritionist, is the author of numerous books published by the American Diabetes Association and the blog EatHealthyLiveWell found on her website,