The GAO sent undercover staff members to ask common questions of supplement retailers, using consumers over the age of 65 because most of them take prescription medication with which a supplement could interact. The seniors’ inquiries included: Is ginkgo biloba safe to take with aspirin? Can ginseng fend off cancer? What about replacing prescribed blood pressure medication with garlic supplements?
The queries got resounding yes’s from supplement sales staffs, the GAO found—but they are big no’s per the National Institutes of Health. A combination of ginkgo and aspirin can increase the risk of internal bleeding. Ginseng has not been scientifically proved to cure any diseases and should be avoided for those with breast and uterine cancers, according to the NIH. Garlic has not been shown to significantly lower high blood pressure—and supplements are not intended to replace prescribed drugs.
Even better: "Of the 40 herbal supplements tested for the GAO investigation, 37 contained trace levels of at least one hazardous compound. Other analyses have found contaminants that include steroids and even active pharmaceuticals"