Last year Americans spent $22.5 billion on dietary supplements, taking everything from a standard multivitamin to fish oil for the heart to magnesium for healthy bones. But how do we know which vitamin pills we need and which we don't? And at what doses do the risks outweigh the benefits?
Dr. Eric Rimm at the Harvard School of Public Health sat down with ABC's Medical Editor Dr. Tim Johnson to discuss some of the more talked about vitamins, how much of them we should be taking and whether too much can be detrimental to our health.
In a field filled with controversy, most nutrition experts agree on one thing: food, not pills, is still the best way to get essential micronutrients. Our bodies seem to process the vitamins in food better. And people who eat a healthy diet — getting at least five servings of fruits and vegetables each day, along with whole grains and lean proteins — get the vitamins and minerals they need.
Unfortunately, these days most Americans are falling short of that goal. But reaching for a vitamin pill should not be the first step toward solving that problem, Rimm says. "A supplement is called a supplement because it's supposed to be supplementing a healthy lifestyle," he said.
If your diet is just average, here's Rimm's advice: "Get yourself off the average diet and move to a healthier diet, and exercise three times a week."
A diet that includes breakfast cereal, juices, dairy products and fruits and vegetables means you're probably getting plenty of vitamin A. Most of our vitamin A comes from a precursor vitamin, beta carotene, found in the orange and red vegetables that we eat. And our bodies are smart enough to make just the right amount. That's why hardly anyone needs to take a vitamin A pill. In fact, excess amounts of vitamin A in our body can be worrisome, Rimm said.
Another vitamin we hear about lately — because it's been added to our packaged food, cereals and grains — is folate, a water soluble vitamin B. Folate is important for a developing fetus because it can reduce neural tube defects. That's why the United States as well a number of other countries fortify the flour supply with folate. Folate also has been shown to reduce the risk of heart disease. But according to Rimm, most healthy people do not need to take folate supplements. "We are already getting more folate just from having hamburger buns and bread with our sandwiches," he said.
Vitamin C is often taken in megadoses by people to fight colds and relieve stress. But while taking vitamin C in excess doesn't seem terribly dangerous, it's also not beneficial. The biggest thing it gives you is expensive urine, Rimm says. "People who take a lot don't use it and just get rid of it," Rimm said.
Recently, vitamin D deficiency has become a hot topic. Studies find that 40 percent of Americans don't get enough vitamin D, commonly known as the sunshine vitamin. And vitamin D deficiency has been linked to cancers and heart disease. Because most people are staying out of the sun or using sunblock, and because we simply can't get enough vitamin D from the foods we eat, Dr. Michael Holick, director of the Vitamin D, Skin and Bone Research Laboratory at Boston University School of Medicine, recommends that all adults and children take a vitamin D supplement of 1,000 units every day.