Published Articles: Newsweek - January 16, 2006

The Gurus' Guide To Daily Nutrition

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JoAnn Manson PROF., HARVARD MEDICAL SCHOOL
She takes: Calcium (1,000mg daily), vitamin D, multivitamin
Tip: For best absorption, no more than 500mg of calcium per dose

Leah Gourley / HMS

I'm not particularly adamant about recommending multivitamins to everyone. I think some people do have diets that are adequately balanced and they can do without a multivitamin. But it is a good form of insurance, especially if your diet is not consistently balanced. I encourage people to try to get their vitamins and minerals from food sources, but I do recognize that a balanced diet isn't always possible with our hectic lifestyles.

I take a multivitamin and calcium—500mg twice a day. It's best not to take more than 500mg in any one dose because then you might not get full absorption of the calcium. I also take vitamin D (400 IU twice a day). There's increasing evidence that vitamin D is important for bone health and also [for preventing] cancer, diabetes and cardiovascular disease. Most Americans are deficient in vitamin D, and American diets tend to be low in calcium. During pregnancy, I took folic acid, too. The amount of folic acid in a multivitamin (about 400mcg) is OK prior to conception. But once you're pregnant you need to begin taking more folic acid. The folic acid you get in a multivitamin is also important throughout your life. These are the supplements for which I think the evidence is strongest.

Fish oil may also be beneficial for people who don't eat a lot of fish with omega-3 fatty acids. It's reasonable to consider fish-oil supplements and increased intake of flaxseed oil or alpha-linolenic acid. That has been linked to a lower risk of cardiovascular disease. Clinical trials of fish oils have been limited, and more research is needed. But there's enough research to recommend at least two servings a week of fish or—if you eat very little fish—a fish-oil capsule, increased intake of flaxseed or alpha-linolenic acid.

We do a lot of research in this field and most randomized clinical trials of vitamin supplements have been disappointing, including those with vitamin E and beta carotene, and even folic acid for the prevention of cardiac problems. This underscores the importance of vigorous testing before making public-health recommendations. Some studies have even suggested risks with increased doses, especially beta carotene. We have to be concerned about taking megadoses of single supplements. Before we go out and recommend megadoses of vitamins, we need to ask if there are randomized clinical trials that show benefits.

Continued
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