Does good health come in the form of a pill? A growing body of research suggests otherwise.

Last week, an eight-year study of more than 160,000 postmenopausal women found that the ones who took multivitamins did not lower their risk of cancer, heart disease or early death.

Does this mean vitamins are a waste of money? Not necessarily. Local nutrition experts say even if vitamins don’t prevent heart attacks or cancer, there may be other benefits.

"I was always told that if you eat right, you don’t need a vitamin," said Mary Ann Clever, a registered dietitian at the Longstreet Clinic in Gainesville. "But with the kind of lifestyles we lead, it can be a form of insurance."

Mary-Ann Johnson, professor of foods and nutrition at the University of Georgia, said there are three nutrients in particular that she’s concerned about.

"It can be difficult to get enough calcium, vitamin D and vitamin B12, even with a well-balanced diet," she said.

Those elements are essential, especially for elderly people.

"Vitamin D and calcium have been proven to reduce the risk of bone fracture," Johnson said. "And a deficiency of B12 can lead to cognitive impairment and blood disorders."

Those nutrients can be purchased as individual supplements, but most dietitians believe a multivitamin is safer. It contains the recommended daily amount of each vitamin or mineral, but usually not more than that.

"I do not recommend large doses of single vitamins, because people tend to overdo it," said Clever.

Some vitamins, such as the B complex and C, are water-soluble, meaning whatever the body doesn’t need is excreted in urine. But others, including vitamins A, D, E and K, are fat-soluble. They accumulate in the body’s tissues and can become toxic.

"There’s a fine line between too much and too little," said Connie Crawley, a nutrition specialist with the Agricultural Extension Service at UGA.

Dietitians say the nutrient that they’re most concerned about is vitamin D. Scientists now believe that the majority of Americans may be deficient in this vitamin.

That’s an odd situation, considering that your body has access to this vitamin even if you eat nothing at all.

Your skin automatically manufactures vitamin D when exposed to sunlight. But most people don’t get enough because they rarely spend time outdoors.

Many doctors now advise patients at risk for osteoporosis to take both calcium and vitamin D, to keep their bones strong.

"I never took a vitamin until I was in my 40s, and that was mainly because I became a little concerned about vitamin D," said Crawley.

Johnson said she also takes a multivitamin, even though she eats a balanced diet. "I recently turned 50 and started thinking more about my health," she said.

Johnson doesn’t have any illnesses that would result in poor nutrition. But she said there are certain groups of people who should definitely take a multivitamin, including pregnant women, people on weight-loss diets, and people with medical conditions that can cause deficiencies.

Vitamins are also recommended for women who might become pregnant, because it’s important that they get enough folic acid even before they know whether they’ve conceived. Lack of folic acid can cause the baby to have spina bifida or other birth defects that occur just as the embryo is forming.

Elderly people also may need vitamins, either because they don’t eat enough or their body doesn’t absorb nutrients well.

But for people who don’t fall into one of the high-risk groups, supplements are optional and sometimes expensive.

"If you’re a pretty healthy person, you may be wasting your money," said Miclah Hood, a registered dietitian at Northeast Georgia Medical Center.

Ironically, those most likely to buy vitamins are the ones who don’t need them.

"About 40 percent of Americans take vitamins," said Johnson. "But the people who take them tend to be the ones who already eat healthy."

On the other hand, people with terrible diets should not assume that a vitamin will reverse the harm from all the junk food they’re eating.

"Don’t take the attitude that ‘I don’t have to eat right because I’m taking this pill,’" said Clever. "It does not replace food, not by any means."

The truth is, scientists still don’t know exactly what it is in food that keeps us healthy. For example, researchers once observed that people who ate fruits and vegetables were less likely to get cancer. They assumed it was because fresh produce contains cancer-fighting antioxidants such as vitamin C and beta-carotene.

But in studies where subjects were given antioxidants in pill form, their risk of cancer didn’t decrease. Apparently, the antioxidants need to interact with other elements in our food.

"They’re called phytochemicals," said Johnson. "There are hundreds of them. We haven’t identified all of them, and we don’t yet understand how they work. So if a company claims they have a pill that contains all these nutrients, that’s totally bogus."

Crowley said no food or supplement is going to make people healthy unless they’re also making lifestyle changes.

"Vitamins are only part of the package," she said. "We know (the risk of) chronic disease goes down when you exercise."

And in a tight economy, buying vitamins might not be the best use of health care dollars.

"Right now, healthy food is a luxury for some people," said Crowley. "But if money is limited, I would spend it on higher quality food, not on vitamins."