It's an important issue because so many people take these products which carry risks, including potentially harmful interactions with prescription drugs, and some patients take dietary supplements in place of conventional medicines, the researchers said.
They analysed transcripts of audio recordings made during office visits by nearly 1 500 patients to 102 primary-care doctors between 1998 and 2010. Of those patients, about 350 had discussions about more than 700 dietary supplements, according to the study, which was published recently in the journal Patient Education and Counseling.
"This is the first study to look at the actual content of conversations about dietary supplements in a primary-care setting," study primary investigator Dr Derjung Tarn, an assistant professor of family medicine at the David Geffen School of Medicine at the University of California, Los Angeles, said in a university news release.
"The bottom line was that discussions about meaningful topics such as risks, effectiveness and costs that might inform patient decisions about taking dietary supplements were sparse," Tarn said.
Five major topics
The researchers focused on five major topics related to dietary supplements: the reason for taking them, how to take them, potential risks, effectiveness and cost or affordability.
On average, fewer than two of the topics were discussed during the office visits. All five topics were covered during discussions of only six of the more than 700 supplements. None of the topics arose for nearly 300 of the supplements patients told their doctors they were taking.
The researchers did find that discussions about herbal and related supplements were more thorough than those about vitamins and minerals. This is important because herbal and related supplements are more likely to have potentially harmful interactions with conventional medicines.
Both the US Food and Drug Administration and the US National Institutes of Health suggest that patients consult with their doctors before starting to take dietary supplements, the researchers noted.
The U.S. Food and Drug Administration has more about dietary supplements.