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agate
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Joined: 17 May 2006
Posts: 5694
Location: Oregon
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 Posted: Wed Sep 04, 2013 6:52 pm Post subject: About multivitamins |
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From the Berkeley Wellness Letter, August 31, 2013:
Do You Need a Multivitamin?
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Multivitamin/mineral pills are the most commonly used supplements in the United States. A multi can be a good way to make up for nutritional shortfalls. But many people expect too much from their multivitamins, which are purported to help prevent a wide range of diseases. Over the years, various observational studies have indeed suggested that people who take a multi have a lower risk of various diseases. The results of clinical trials, however, have been largely disappointing, with a 2012 Harvard study being a notable exception.
What the studies show
A few years ago, a panel of advisors at the National Institutes of Health concluded that the evidence concerning the effectiveness and safety of multivitamins is limited and inconclusive.
A 2009 study published in the Archives of Internal Medicine analyzed data from the landmark Women’s Health Initiative and found that multivitamin use did not reduce the risk of cancer or cardiovascular disease.
Meanwhile, two studies in the American Journal of Clinical Nutrition in 2010 analyzed a decade of data from more than 30,000 Swedish women. One found that women who took multivitamins were 27 percent less likely to have a heart attack. In contrast, the second study linked multivitamin use to a 19 percent increased risk of breast cancer. Still, these were observational studies, and do not prove cause and effect.
In 2012, a well-designed clinical trial from Harvard involving 14,600 physicians found that those taking a basic multivitamin (mostly 100 percent of the RDAs) were 8 percent less likely to develop cancer over 11 years compared to those taking a placebo.
Of course, multivitamins vary greatly, so even if there are benefits, it would be very hard to know which components are responsible, or at what doses.
A risk of taking too much?
Multivitamins are generally assumed to be safe, but some contain excessive doses of nutrients—10 or more times the recommended daily intakes. For instance, some supply high doses of vitamin A, which may weaken bones. And large doses of copper can interfere with the absorption of zinc, and vice versa.
Are you a candidate?
Consider taking a daily multi if you are in one of the following groups.
• You are over 60. Most older people don’t get the nutrients they need, for various reasons. Major problem nutrients for older people are vitamin D, certain B vitamins, and magnesium.
• You are a woman of childbearing age. Women capable of becoming pregnant need at least 400 micrograms daily of folate (the form in supplements is called folic acid). This B vitamin helps prevent neural tube birth defects. In addition, premenopausal women can benefit from the iron in a basic multi.
• You are pregnant or breastfeeding. You should probably take a multi, but discuss your special needs with your doctor.
• You are a strict vegetarian. If you eat no animal products, you may not get enough vitamin B12, zinc, iron and calcium.
• You are on a weight-loss diet or are a heavy smoker or drinker.
But keep in mind
If you take a multivitamin/mineral pill, it cannot substitute for a healthy, balanced diet. Foods—particularly fruits, vegetables and whole grains—provide fiber as well as many potentially beneficial compounds not found in any pill.
7 Tips for Buying Multis
A multivitamin need not cost more than a few cents a day. Store-brand and generic products are usually as reliable as brand-name pills.
Look for 100 percent of the Daily Value of the following vitamins: D, B1 (thiamin), B2 (riboflavin), B3 (niacin), B12, and folic acid.
The product should also contain at least 20 micrograms of vitamin K.
Avoid very high doses of folic acid.
Look for lower levels of vitamin A—no more than 3,000 IU. Getting more than about 6,000 IU of vitamin A from food and supplements increases the risk of fractures. Beta carotene is safe for your bones, though high doses may increase the risk of lung cancer in smokers.
Look for up to 100 percent of the Daily Value of these minerals: copper, zinc, iodine, selenium and chromium. Most products also contain some magnesium and tiny amounts of trace minerals such as boron, manganese and molybdenum. Since calcium is bulky, a multi won't contain enough to satisfy the recommended daily intake, so you may need a separate calcium supplement.
Premenopausal women should look for 100 percent of the Daily Value of iron. Men and postmenopausal women are better off with a multi containing no iron.
Here are some words you don’t need to see on the bottle: "high-potency," "senior formula," "stress formula," "starch-free," "natural" or "slow-release." Ingredients such as enzymes, hormones, herbs and amino acids serve no purpose and add to the price. |
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