Like many Americans, Brandon Commiskey takes a daily multivitamin and mineral supplement. He's a healthy enough guy. At 26, he has no medical conditions, exercises and eats fairly well. Or tries to.
"I'm broke, so sometimes a 99-cent hamburger is lunch," says Commiskey, of Walnut Creek, Calif. "I wouldn't say the multi vitamin is a full replacement for eating right. I see it more as maintenance."
It's difficult to discern what multivitamins do — if anything. Yet Americans continue to shell out $23.7 billion a year on supplements, even following recent news that the high levels of vitamin D once thought to ward off chronic diseases and improve health problems might be unnecessary or harmful. While some experts think certain populations might benefit from multivitamin use more than others, they all agree that a healthful diet and exercise serve you better than popping a pill.
The biggest evidence comes from the Women's Health Initiative, or WHI, a groundbreaking study published last year. It followed 162,000 women ages 50 to 74 who took multi vitamins for eight years and found that the supplements did not reduce the risk of cardiovascular diseases or any of the major cancers, including breast, lung, stomach, kidney, colorectal and ovarian.
"I wasn't surprised," says Marian Neuhouser, lead author and associate member in the Public Health Sciences Division at the Fred Hutchinson Cancer Research Center in Seattle. "A lot of other dietary supplement studies have shown the same thing."
However, because this is the largest study of its kind — women came from 40 sites across the country — the results provide concrete evidence about the efficacy of multivitamins, she says. And, because the study focused on post-menopausal women, the results might not apply to men, Neuhouser adds.
But the 2008 Physicians' Health Study II, a clinical trial of nearly 15,000 male doctors, revealed that taking vitamin C or E supplements did not lower the risk of cancer or cardiovascular disease. That same year, the Journal of the American Medical Association published a study of 35,000 men which stated that high doses of vitamin E and selenium, taken for an average of 51/2 years, did not prevent prostate cancer.
According to Neuhouser, the WHI study focused on multivitamins because they are the most commonly used supplement. More than half of all Americans take them, and they tend to be white, active and have college degrees. They also tend to eat more produce and less fat than non-users.
For those who don't eat their veggies, a multi vitamin isn't going to do a darn thing. Sorry.
"It's a myth that if you have a poor diet and take a multivitamin, it will somehow make up for it," Neuhouser says. "Multi vitamins don't contain all of the benefits of plant foods and whole grains. So if people have tight budgets, they're better off spending their money on produce."
Nora Norback, a registered dietitian with Kaiser Permanente, said she agrees. But she also thinks that in our "overfed and undernourished" society, multivitamins might help with dietary gaps — and there are many.
"Many of us don't eat in a way that we're meeting our nutrient needs," says Norback, who works in Richmond, Calif. "A multi vitamin and mineral supplement appears to bring us up to the levels with vitamin E, A, B6 and zinc."
Her research comes from the government's Health and Nutrition Examination Survey. "But if you're taking it thinking it will correct inadequate levels of calcium, magnesium, or potassium, think again, because it doesn't."
Norback estimates that 40 percent of adults and children aren't meeting recommendations for calcium, magnesium and fiber. And then there are people who are most vulnerable to nutrient deficiencies: Adults 65 and older, vegans, vegetarians, the alcohol-dependent and those with food insecurity, meaning people who don't have enough money to consistently provide nutrient-rich foods for themselves, she explains.
"They might benefit from a multivitamin and mineral supplement," she says.
Pregnant women benefit from prenatal multivitamins, particularly with adequate folic acid, which helps prevent birth defects, she says.
Bottom line? Multivitamins aren't harmful, but they also haven't been proven to prevent disease. So, do yourself a favor.
"Spend the cash on vitamins in their natural packaging," Norback says. "If you eat a balanced diet and exercise, multivitamins aren't going to do much for you anyway."