The shelves of your local supermarket and drugstore are probably brimming over with a bewildering array of dietary supplements and herbal remedies. Many are advertised to have benefits that will improve your sex life, your memory or your figure.
But how real are these claims? And how safe are the ingredients in these supplements?
According to many industry experts, the problems with herbal supplements are just beginning to be understood.
"One out of four has some sort of problem," said Dr. Tod Cooperman, physician and president of ConsumerLab.com, an independent laboratory that tests dietary supplements. "People should keep that in mind."
In many cases, Cooperman's group has found that some name-brand supplements contain only a fraction of the ingredient on their labels -- if any at all.
"Some have none, some have 80 percent, some have 20 percent," Cooperman said.
Another problem with supplements involves contamination. In two separate cases last month, pesticide residue was found in a batch of ginseng at a distributor in New Jersey, and toxic heavy metals like mercury, lead and arsenic were discovered in herbal supplements on sale in stores in the Boston area.
Researchers have also found significant amounts of Viagra and Cialis, prescription medicines for treating erectile dysfunction, in "natural" sexual enhancement supplements. "There are increasing instances of them being spiked with pharmaceutical products to make them more effective," said Cooperman.
Besides the concerns over the safety of individual products, many doctors warn their patients about the way herbal medications can interact with prescription medication.
"Most of the risks aren't known," said Dr. Neil Brooks, a family physician in Vernon, Conn. "What they're doing is adding chemicals to their bodies and we don't know what the effects are, independently or in combination."
"I had a patient the other day who had at least 12 things she was taking," Brooks said.
But many patients choose not to reveal to their doctors the supplements they're taking. In a report released today, the Institute of Medicine states that fewer than 40 percent of patients fully disclose to their doctors what supplements they use.
The IOM report, entitled "Complementary and Alternative Medicine (CAM) in the United States," also notes that users of alternative medicines like dietary supplements generally use more than one type and use them in combination with more conventional medical treatments.
About 40 percent of Americans routinely use one or more dietary supplements. By most estimates, sales of supplements in the United States alone have created a $19 billion industry.
Even the most hardened skeptics understand that many dietary supplements have benefits that are universally accepted.
"Vitamins and minerals at RDA [recommended dietary allowance] levels are needed to prevent deficiencies," said Cooperman. "Some of the greatest examples are calcium, folic acid and iron."
Those three supplements are used to prevent osteoporosis, pregnancy complications and blood deficiencies, respectively.
"For nutritional supplements, there are a wide variety of benefits," said Annette Dickinson, nutritionist and president of the Council for Responsible Nutrition, a trade association of dietary supplement manufacturers.