What Vitamin Should I Take?

The smart way to select a supplement

By Kathleen Zelman, MPH, RD/LD
WebMD Weight Loss Clinic - Expert Column

Even with the best dietary intentions, we often fall short of meeting all our nutritional needs. One answer is a daily multivitamin, which is safe, effective, and can go a long way toward correcting any nutritional deficiencies.

Of course, the ideal way to get your nutrients is still from food. Food not only supplies vitamins and minerals, but also gives us fiber and a host of other healthy compounds, like phytochemicals and antioxidants, that interact with each other in ways that supplements can't.

The scientific community used to believe that a varied, healthful diet would provide all the vitamins and minerals we need. But recent surveys show that most American diets fall short of satisfying the minimum daily requirements for several vitamins and minerals. (Still, we rarely see actual deficiencies in the U.S., simply because we eat plenty of food.)

The culprit? Often, it's life in the fast lane -- chowing down on too much fast food and not enough fruits, veggies, whole grains, and low-fat dairy. Researchers have concluded that a single daily multivitamin/mineral pill may be the answer for achieving optimum health and preventing chronic diseases.

At the WebMD Weight Loss Clinic, we encourage everyone to take a daily multivitamin. This is especially important for people whose calorie prescription is less than 1,500 per day.

Under certain conditions -- for example, if you're pregnant or following a strict vegetarian diet -- you may need additional supplements. Check with your doctor or a registered dietitian for more information.

Nutritional Insurance

Approximately 40% of Americans take supplements, according to the third U.S. National Health Examination Survey. And the most popular supplement is the multivitamin.

One important point: a daily multivitamin supplements your diet; it's not intended to correct a bad diet. The benefit of a daily multi is that it can make up for minor deficiencies in your diet that could eventually help lead to chronic disease. In fact, a study published in the August 2003 Journal of Nutrition found that men and women who took multivitamins significantly reduced their risk for a first heart attack.

The body needs roughly 40 vitamins and minerals each day for good health, and it's not always easy to get all of those from food. Taking a daily multivitamin certainly won't hurt, even if your diet is already chock full of vitamins and minerals.

Too Much of a Good Thing

Taking individual vitamin or mineral supplements can be a bad idea; it's easy to overdose on certain nutrients that can be toxic in large amounts.

To help guide consumers, the government sets safe upper limits for most vitamins and minerals. So always read the label on the package, and keep in mind the food that you eat also contributes vitamins and minerals.

Keep in mind that some supplements you can find on the shelves contain herbs or other unnecessary ingredients that can be potentially harmful. Unlike drugs, supplements aren't required to undergo rigorous testing or get government approval, leaving the safety of these products up to the manufacturers.

The simplest and best way to meet your nutritional needs is to take one multi each day, unless your doctor prescribes specific vitamins or minerals. If you are taking more than a daily multi, discuss it with your doctor, just as you would any medication.

Choosing a Multivitamin

The easy part is deciding that a daily multivitamin is right for you; the challenge is selecting one from among the hundreds that line the drugstore shelves.

So before you buy, do a little comparison shopping. Bring along your reading glasses, and take a few minutes to review the percent of Daily Values (DV) for each nutrient the supplement contains.

To find the least expensive multivitamin supplement that still provides all the vitamins and minerals you need, keep these tips in mind:

  • Avoid supplements that provide more than 100% of the DV for any vitamin or mineral.
  • Choose a supplement with no more than 3,000-3,500 International Units (IUs) of retinol or vitamin A.
  • Men and postmenopausal women should choose multivitamins with 50% or less of the DV for iron.
  • Don't expect to find 100% of the DV for calcium or magnesium in a multivitamin. Adding these would make the pills very large.
  • Look for the USP (United States Pharmacopeia) symbol, a mark of a quality product.
  • Most additives, such as herbs, are unnecessary and just drive up the price of the supplement.
  • Supplements designed for certain age groups or sexes tend to be pricier. You can usually find a similar formula in a generic brand.

Originally published Sept. 16, 2004.
Medically updated Aug. 1, 2005.

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