(HealthDay)—A new survey estimates that one in seven people in the United States regularly takes supplements that aren't vitamins or minerals—such as fish oil, echinacea or ginseng—but only 30 percent of them have had a doctor or nurse recommend supplements.
About one-third of supplement users have not alerted their doctor, even though they may take the drug for a potentially serious health issue, such as high blood pressure, arthritis or depression, the survey found.
"These are things that clinicians often treat with more complex treatments," said Robert Blendon, a professor of health policy at Harvard School of Public Health and co-author of a letter in the Nov. 19 issue of the journal Archives of Internal Medicine. "They need to be aware that people are using this as one form of treatment."
Although supplement use is widespread, not much is known about why people take these capsules, syrups and tablets, the researchers said. To address that gap, they surveyed nearly 1,600 people in the United States in 2011, weighing the answers to make the demographics of the group reflect those of the country at large.
Of those surveyed, 38 percent said they'd taken supplements—but not vitamins or minerals—in the past two years, and 14 percent said they did so regularly.
The most common reasons for taking supplements were to feel better, to improve energy and to boost the immune system. Smaller numbers of respondents reported taking supplements to treat digestive issues (28 percent), relieve pain (26 percent), lower cholesterol (21 percent) or blood pressure (16 percent), or to improve mood or depression (12 percent).
Fish oil tablets were the most frequently taken supplements. About one in four respondents said they had taken fish oil or related omega-3 supplements in the past two years.
The authors noted that perception of benefits rather than quantifiable, research-based evidence appears to drive many people to take supplements. Even if a government-funded study were to denounce claims made by supplement manufacturers, one-fourth of respondents said they would disregard it. And more than 80 percent said it was important that they have access to supplements.
The study didn't look at the potential benefits or harms of supplement usage. "We were more interested in what they were taking them for," Blendon said.
The U.S. Food and Drug Administration, however, cautions that although supplements can boost health, they can lead to complications—even life-threatening ones. For instance, taking them with prescription or over-the-counter medications can cause harmful interactions.
The report didn't note the age, gender or other characteristics of survey respondents, and some experts feel the report is flawed by such limitations.
Jeffrey Blumberg, professor of nutrition science and policy at Tufts University in Medford, Mass., said too little information about the respondents is available to make the findings meaningful.
Michael Ormsbee, assistant professor of nutrition, food and exercise sciences at Florida State University in Tallahassee, wonders if rewording some questions would influence the responses.
For instance, regarding the question about a government study discrediting a supplement, he wonders what the response would be "if the question was reversed to see if they would be impressed by government studies showing that certain supplements do work." Would they be more likely to consume the supplements? he wondered.
"It appears that people are driven by individual perception rather than research to back up products they take," Ormsbee said. "The logical question is what drives these perceptions—TV, gym friends, peer pressure, experts, media outlets?"
In some cases, supplements may be appropriate, he said, but healthy eating and exercise need to come first.
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For more about dietary supplements, visit the U.S. National Library of Medicine.