(AP) -- About half of U.S. adults take vitamins and other dietary supplements - a level that's been holding steady for much of the past decade, new government figures show.
But the data also show a booming number of older women are taking calcium.
Federal officials released figures Wednesday showing that the use of dietary supplements has grown since the early 1990s when it was about 42 percent. The data shows use leveled off in 2003 through 2008, with about half of adults 20 and older taking at least one dietary supplement.
The biggest change was for calcium. Two-thirds of women 60 and older take it, up from 28 percent in the early 1990s.
Experts note the ranks of the elderly have been growing, and include many women who have been encouraged for years to take calcium to help protect against osteoporosis.
The information comes from national, in-home surveys in 1988-1994 and 2003-2008. The surveys in the past decade included more than 2,000 people each year. Interviewers not only asked participants what supplements they took, but also asked to see the bottles to verify their answers.
Use of multivitamins - the most popular supplement - crept up to nearly 40 percent.
Most people who take vitamins and other supplements are educated, have good incomes, eat pretty well and already get the nutrients they need from their diets, the surveys suggests.
"It's almost like the people who are taking them aren't the people who need them," said Regan Bailey, a nutritional epidemiologist with the National Institutes of Health.
Federal surveys have only recently started asking people why they take supplements, Bailey said.
The government supports some supplements as an option for certain people - such as iron for women who are pregnant, folic acid for women thinking of getting pregnant and calcium for older women.
But health officials say people should talk to their doctors first, and consider enriched foods that can accomplish the same goal.
Much of the new data is in a Centers for Disease Control and Prevention report released Wednesday.
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More information: CDC report: http://www.cdc.gov/nchs