remedies, herbs, formulas, and other dietary supplements are
available in health food stores, drugstores, and even some grocery
stores. The labels read "improve memory," "promote
higher energy levels," or "maintain healthy
digestion." And many consumers seem to believe the claims.
According to the U.S. General Accounting Office, an investigative
division of Congress, about $31 billion was spent on dietary
supplements and related products in 1999.
But on these same labels is
the disclaimer required by federal law: "This statement has
not been evaluated by the Food and Drug Administration. This
product is not intended to diagnose, treat, cure, or prevent any
disease." So how much is really known about these dietary
"If the product is a
dietary supplement, there is a lot we don’t know," says Kelly
Smith, Pharm.D., drug information specialist and assistant
director, University of Kentucky Hospital Drug Information Center.
"Dietary supplements are not tested in thousands of people
before they are marketed like drugs are tested. This means that
the evidence for the product’s effectiveness is based mainly on
historical use rather than scientific studies."
Limited scientific studies
have been done for some products. The Office of Dietary
Supplements (ODS) at the National Institutes of Health coordinates
research and funding for research on the effectiveness of dietary
"If you are considering
using a dietary supplement, choose one that references clinical
studies rather than just testimonials," says Smith, who also
is a clinical assistant professor, Pharmacy Practice and Science
Division, UK College of Pharmacy.
Another unknown about these
products is the potential side effects and interactions with
prescribed or over-the-counter medications.
For example, the popular
herbal remedy St. John’s Wort, often taken for treatment of mild
depression, has been shown to interact with drugs used to treat
cancer and AIDS and with birth control pills. St. John’s Wort
makes these medications up to 50 percent less effective in certain
Other dietary supplements have
been associated with liver damage, kidney failure, and even death.
These serious side effects can occur rapidly or over time.
The quality of dietary
supplements can also be uncertain. The FDA does not regulate the
manufacturing of these products.
Consumers can try to find
products of higher quality by looking for products labeled "USP"
or "NF," which follow the standards set by the U.S.
Pharmacopoeia, a non-governmental scientific organization that
develops standards for medications and health care products.
If you are taking or
considering taking a dietary supplement, Smith says, "Because
so much is unknown about dietary supplements, it’s important that
consumers get all the information available by talking with their
pharmacists or physicians about these products."