(WebMD) About two-thirds of people taking herbal supplements to treat a health condition don't check scientific guidelines, say University of Iowa researchers.

The researchers focused on 609 people who reported treating a specific health condition with any of 10 herbal supplements, including echinacea, ginseng, garlic, St. John's Wort, soy or kava kava.

Bardia's team checked to see if there was scientific evidence supporting the use of those herbal supplements for the participants' health conditions.

Overall, about 55% of the participants used herbal supplements backed by scientific evidence for their condition.