& Alan Titchenal Monday,
March 25, 2010
Is a multivitamin a smart idea?
People past the age-50 milepost often consider taking supplements in hopes of feeling better, maintaining health, having more energy and avoiding or treating chronic diseases. Most widely used are the multivitamin/mineral, or "multi" supplements, that attempt to cover all the bases in one pill. But the astute consumer will find plenty of contradictory information about the value of multis.
Question: Why is there so much confusion about multi supplements, even in research literature?
Answer: It is difficult to compare people who take multis to those who don't. Research shows that people who take supplements generally are more concerned about their health and typically have better diets than nonusers. Also, consuming the many foods fortified with vitamins and minerals can be like taking a multi. An estimated 65 percent of Americans consume fortified foods, making it difficult to accurately measure nutrient intake when studying large numbers of people. Due to these and other complexities, the scientific jury is still out on whether they benefit health.
Q: Does taking a multi daily reduce the risk of chronic disease?
A: Studies of specific nutrients in multis have found both benefits and harm. For example, taking calcium and vitamin D supplements together has been shown to benefit bone health in postmenopausal women. But excessive calcium intake was associated with increased risk of kidney stones in one study. So, more is not always better.
Also, the formulation of multis can vary greatly, making it difficult to generalize. Having more of a particular nutrient in a multi may not be a good thing. Some nutrients can interfere with the absorption of others. For example, a multi with "extra calcium" will reduce the absorption of the iron and other trace minerals in the supplement.
Q: How can the average person make an educated decision?
A: First, ask yourself if you are eating a wide variety of foods in reasonable amounts from all the food groups. If you do, then a multi is less likely to be needed. But as a person ages, calorie needs typically drop and total food intake decreases. So even a reasonably balanced diet could run short on nutrients.
Q: Can multis cause harm?
A: It depends on the nutrient formulation and your overall diet. Some formulations may exceed safe levels for certain nutrients. And if you eat fortified foods plus a multi, you may be at greater risk of exceeding safe limits for some nutrients. For information on safe limits, visit www.nutritionatc.hawaii.edu/UL.htm.
The goal of good nutrition is to meet nutrient needs from foods and/or supplements combined, not exceeding reasonable amounts. More is not always better.
Alan Titchenal, Ph.D., C.N.S. and Joannie Dobbs, Ph.D., C.N.S.
are nutritionists in the Department of Human Nutrition, Food and Animal Sciences,
College of Tropical Agriculture and Human Resources, UH-Manoa.
Dr. Dobbs also works with the University Health Service
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