Why so many patients look to dietary supplements for answers

Although Americans' use of dietary supplements was known to have increased during the past three decades, it was unclear why adults were taking them — until now.

Researchers have identified the key reasons adults use dietary supplements, and it's not because physicians are prescribing them. Only 23% of supplements taken by patients were based on recommendations by physicians and other health professionals, according to the study, which was published online Feb. 4 in JAMA Internal Medicine, formerly the Archives of Internal Medicine.

Driving many people to use the products are the goals of improving overall health (45%) and staying healthy (32.8%), the study showed. These findings come amid other recent reports concluding that dietary supplements often lack reliable evidence to support their health claims.

Physicians can use the new data to focus their conversations with patients about dietary supplements, said lead study author Regan L. Bailey, PhD, RD. For instance, because many people take the products to improve or maintain health, physicians can become familiar with the effectiveness of supplements and discuss those facts with patients.

“The concern is … people are spending money for products that they believe will prevent diseases. Whether or not that's true, we need more science to understand that,” said Bailey, a nutritional epidemiologist in the Office of Dietary Supplements at the National Institutes of Health.

There also are worries that supplement use without physician guidance could lead to harmful interactions with ingredients in different supplements or with prescription medications the patients also are taking, she said. “There has to be an open dialogue between physicians and people who are using supplements.”

Beyond asking patients about their use of dietary supplements, doctors should inquire about what information led the patients to take the products, said Reid B. Blackwelder, MD, a family physician in Kingsport, Tenn. Asking that question provides a more complete picture of the factors contributing to supplement use, as well as a clearer idea of health concerns and goals, said Dr. Blackwelder, president-elect of the American Academy of Family Physicians.

“I routinely explore in a nonjudgmental fashion what my patients are taking,” he said. “I want to know why they're using it and where they learned of it. [This] lets them know I'm open” to discussing what they're doing.

Dr. Blackwelder said he doesn't discourage patients from using a particular supplement but tries to guide them in the proper direction. “My job is to provide the information. I tell them, 'Here's what I've seen in the studies.' ”

Healthy adults use more supplements

Researchers for the JAMA Internal Medicine study examined data on nearly 12,000 adults 20 and older who participated in the Centers for Disease Control and Prevention's National Health and Nutrition Examination Survey in 2007-08 or 2009-10. They found that almost half of adults reported using a dietary supplement product within the past 30 days.

Supplement use was more common among women (54.4%) than men (43.1%). Adults 60 and older and white respondents reported higher use of the products than individuals of younger ages and other races. Additionally, supplement users were more likely to report very good or excellent health, have health insurance and exercise more frequently than nonusers.

This indicates that healthy people “are taking a more active role in their health” than other patients, said internist Raul Seballos, MD, vice chair of preventive medicine at Cleveland Clinic. He encourages doctors to keep this finding in mind during exams and use it as a reminder that they should ask all patients about supplement use, not just older individuals or those with medical problems.

Multivitamins and minerals were the most common type of dietary supplements reported (31.9% of participants used them), followed by calcium (11.6%) and omega-3 fatty acids and fish oil (9.8%). Overall, the most common reasons for using supplements, after the goals of improving and maintaining health, were aiding in bone health (25.2%), supplementing diets (22%), preventing health problems (20.4%), and aiding in heart health and lowering cholesterol levels (15.1%).

There were some differences, however, among men and women. For instance, bone health was the second-most popular reason women took supplements (35.8%), compared with 11.3% of men who used the products for that reason.

To physicians like Dr. Seballos who care for many patients on supplements, the findings weren't necessarily surprising.

“It didn't change my thinking that much,” he said. “But it did confirm that what I've been seeing” is occurring nationwide.

When talking to patients who use supplements, Dr. Seballos often encourages them to think of other steps they can take to improve their overall health. Such steps could include exercising more frequently, eating a more nutritious diet and establishing a better work-life balance.

“I emphasize that these dietary supplements aren't a substitute for healthy lifestyles,” he said.

Among participants who received a physician recommendation to use a supplement, multivitamins and calcium were the most frequently recommended products, the data show.

Calcium supplements can harm men

In an unrelated study published online Feb. 4 in JAMA Internal Medicine, researchers found that a high intake of supplemental calcium was associated with an increased risk of cardiovascular disease death in men.

During an average of 12 years of follow-up, there were 7,904 cardiovascular disease deaths among men and 3,874 among women, according to the study of 388,229 adults 50 to 71 years old who participated in the National Institutes of Health-AARP Diet and Health Study. They were recruited for the AARP study in 1995 and 1996.

Men who consumed more than 1,000 mg/day of supplemental calcium had an increased risk of total cardiovascular disease death compared with men who did not use the products. Dietary calcium intake was not associated with increased cardiovascular disease death in men or women.

The recommended dietary allowance for calcium in men 19 to 70 years old is 1,000 mg/day, and 1,200 mg/day for men 71 or older, according to the Office of Dietary Supplements. A possible reason for the harmful effects of supplemental calcium on cardiovascular health is vascular calcification, the deposit of calcium phosphate in cardiovascular structures. The study said further research is needed to determine whether there is a gender-specific difference in the cardiovascular effect of calcium supplements.

“Given the extensive use of calcium supplements in the population, it is of great importance to assess the effect of supplemental calcium use beyond bone health,” the study authors said.