“We know that even people who make a concerted effort to add more nutrient-dense foods to their diets still might not be meeting their nutrient requirements,” says Diane McKay, an assistant professor at the Friedman School of Nutrition Science and Policy at Tufts University in Boston.
In 2000, in a study sponsored by a California supplement company, McKay and her colleagues randomly assigned 80 healthy, well-nourished adults who were living in the Boston area to take either a standard multi or a placebo for two months.
“Even in these healthy people, we found a significant boost in the blood levels of certain nutrients up to levels that are associated with a lower risk of disease,” says McKay.
The percentage of multi takers with suboptimal vitamin D levels, for example, dropped from 7 percent to 0 percent, and the percentage with suboptimal vitamin B-12 fell from 42 percent to 27 percent.
McKay’s conclusion: “Taking a multivitamin formulated at about 100 percent of the Daily Value for vitamins and minerals can be a pretty convenient and cost-effective way of filling in the gaps that may exist between what you need and what you’re actually consuming.”
In 2010, the U.S. Dietary Guidelines Advisory Committee identified seven “shortfall nutrients of public health concern”: vitamin B-12, vitamin D, folic acid, iron, calcium, potassium, and fiber.
Multivitamins are not a good source of fiber, potassium, or calcium, which are too bulky to fit into a multi. But a multivitamin can provide close to—or all of—a day’s worth of the other four.
However, multis are only inexpensive insurance if they don’t cost too much. You don’t need to pay more than $5 a month for a high-quality multivitamin.
Source: J. Am. Coll. Nutr. 19: 613, 2000.