Portland, Oregon, resident Teri Brown began taking vitamins when she was 38 years old, facing surgery and radiation for a pituitary gland tumor. Mary Ann Hake of Crooked River Ranch, Oregon, has taken vitamins since she was a child to combat allergies, a poor immune system and the macular degeneration that runs in her family. Susan Thompson in Charlotte, North Carolina, started her vitamin regimen in her early 30s simply because she wasn't eating very well and thought it would help her feel better.

Three women. Three reasons for taking multivitamins. And they are not alone. According to a recent Nielsen survey, 49.8 percent of U.S. households purchased multivitamins last year. Yet in this land of plenty--where obesity is a serious problem--is supplementing our diet really necessary?

"A multivitamin daily is an effective, inexpensive and prudent 'insurance policy' for all Americans," says Jeffrey Blumberg, Ph.D., director of the Antioxidants Research Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging, and professor at the Friedman School of Nutrition Science and Policy at Tufts University.

Susan Finn, Ph.D., head of the American Council for Fitness and Nutrition and a past president of the American Dietetic Association, agrees. "A recent study by the National Health and Nutrition Examination Survey shows that a large portion of Americans fall short on such key nutrients as magnesium, potassium and vitamins A, C and E. In these cases, taking a multivitamin would be beneficial."

While far from unanimous, the general consensus appears to be "yes." The American Medical Association and the Harvard School of Public Health, along with a variety of health experts, favor taking a daily multivitamin.

Choosing the right vitamin

If you've visited the vitamin aisle recently, you know the varieties are almost endless. Where do you begin?

Start with the ingredients label, advises Blumberg. A multivitamin with near 100 percent of the daily value of most vitamins and minerals but without herbal ingredients is ideal.

In addition to basic multivitamins, many companies offer specialized formulas for women, older people and those with other needs. "For women under 50, 1,200mg calcium with vitamin D every day is important," says David Heber, M.D., Ph.D., professor of medicine at the University of California, Los Angeles and director of the

UCLA Center for Human Nutrition. "Women over 50 need 1,500mg since they don't absorb calcium as well as women under 50. Folic acid is already included at levels that are adequate (400mcg) except for pregnant women, who need more folic acid during pregnancy (800mcg)--which they can get in special vitamins made for pregnant women."

Many people use a multivitamin as the foundation for their vitamin regimen and then supplement with additional vitamins to meet their specific needs, activity level, medication use and family history of disease, according to Blumberg. Calcium, for example, is better absorbed by taking smaller amounts two or three times daily. This approach can be successful with proper knowledge; however, Heber warns, "More is not always better."

Hake acknowledges that too much niacin bothers her. And Brown had a scare before her surgery. "I was taking extra vitamin E and I didn't know that it was a blood thinner. The doctor caught it about a week before my surgery and told me to stop immediately."

"If you need help determining if your vitamin and mineral requirements are being met by your diet and if you have special needs that may call for a supplement, consult with a registered dietician," suggests Finn.

Buying your multivitamin

You've decided to take a multivitamin and narrowed your choices, but there are still more questions. Health food store? Drugstore? Grocery store? Tablet, capsule, liquid, chewable? Regular or time-release? Here are a few tips:

* According to experts, purchase location is less important than brand. Heber recommends always selecting multivitamins from a major manufacturer so you know the quality has been carefully controlled.

* Look for the USP seal on the label, suggests Finn. "This seal means the product has been thoroughly tested and meets the standards of the U.S. Pharmacopoeia."

* As with all products, make sure the safety seal is intact and the expiration date hasn't passed.

* Form is a personal choice. "Most people prefer the convenience of a tablet or capsule," says Heber. "Chewable and liquid vitamins are specialty items and don't provide any superior delivery of vitamins into the bloodstream for most Americans."

* Similarly, time-release vitamins are not necessary. "They may work (i.e., slowly release the ingredients)," says Blumberg, "but there is no clinical rationale for this type of product."

Taking your multivitamin

It may sound obvious, but a multivitamin will only work if you remember to take it.

"Multivitamins are best taken with food, preferably the largest meal of the day, to help improve absorption of the nutrients," says Blumberg. "But taking the multivitamin with meals also helps improve compliance, so any meal that proves most convenient for remembering to take them is best."

While far from complete, research does indicate that taking vitamins can help fight such diseases as cancer, heart disease and osteoporosis. However, Finn reminds us that supplements are not a replacement for a healthful, well-balanced diet. "Consuming vitamins and minerals in a variety of food is the best way to ensure you get what you need. We are still learning about how nutrients support each other in their naturally occurring environments. Not all of these interactions may be captured in a supplement."

So pop that pill--but ideally with a healthful meal full of whole grains, fruits, vegetables and lean proteins!

Boost your nutrients!

Experts agree: The best way to get vitamins is from a good diet. Many people, however, would be surprised to learn they're not consuming the nutrients they think they are from their food.

Here are three easy ways to increase your vitamin intake:

Always buy milk in a cardboard container. Studies show that, after just one day in a lit dairy case, milk in a translucent plastic jug loses up to 70 percent of its vitamin A and riboflavin.

Mix your own orange juice from frozen concentrate. Orange juice in prepackaged, ready-to-drink cartons typically contains 25 percent less vitamin C per cup than orange juice from frozen concentrate. And drink it quickly. OJ loses its vitamin C over time; in fact, within four weeks, the amount can drop to zero!

Eat as varied a diet as possible. Even within a certain kind of food, the nutritional content can differ depending on the type. For example, ounce for ounce, cherry tomatoes have twice the vitamin C of larger tomatoes, while fresh red tomatoes contain almost four times the vitamin A of fresh green tomatoes.

HOW VITAMINS ARE ABSORBED

Water-soluble vitamins are easily absorbed by our bodies. We don't store large amounts of water-soluble vitamins and the leftovers we don't need are removed by our kidneys and come out in our urine. Vitamins B1, B2, B3, B5, B8, B12, C, H and Folic Acid are water-soluable vitamins. This means we need to eat a regular diet of foods containing these vitamins to be sure to renew the supply to our bodies (or take vitamin supplements).

Fat-soluble vitamins require bile acids to be absorbed in our bodies. Once absorbed, they are stored as body fat. Eating fats or oils that are not digested can cause shortages of fat-soluble vitamins. This includes using mineral oil frequently to treat constipation or eating the fat substitute Olestra. Vitamins A, D, E and K are fat-soluable vitamins.