For the facts on `natural' remedies, go online

We Americans spend an estimated $20 billion a year on dietary supplements and so-called ``natural" remedies, many of us blissfully -- even willfully -- ignorant of the actual medicinal value, or utter lack thereof, of these products.

It's not entirely our fault that we buy this stuff so blindly. In 1994, Congress limited the power of the Food and Drug Administration to regulate supplements and herbal medicines, which now are allowed to get -- and stay -- on the market unless there is clear evidence of harm.

We've been left largely to our own devices to figure out which remedies work and which are pure snake oil.

Happily, a few reasonably trustworthy websites allow consumers to evaluate how much credible research there is (or isn't) for a particular supplement, how the ``natural" remedy interacts with other such products or with prescription drugs, and what the major side effects are.

(I put ``natural" in quotes, by the way, because the term is meaningless for health products. Pills from health food stores are not intrinsically safe, gentle, or nontoxic just because they are called ``natural." And they're much less likely than prescription drugs to even contain the ingredients listed on the labels.)

To compare my favorite sites, I've tracked how they rate three of the top-selling products: black cohosh, often used to treat hot flashes; echinacea, used to treat and prevent colds; and the combination of glucosamine-chondroitin, used to ease the pain of osteoarthritis. There's little solid science for taking these and many other alternative remedies, but some sites do a better job than others at pointing out the products' shortcomings. Some information on these sites is free, but for details, you often have to pay (typically $15 to $50 per year).

For starters, I recommend the site run by the National Center for Complementary and Alternative Medicine (part of the National Institutes of Health). It is quite helpful and easy to use. To check on echinacea, for instance, go to http://nccam.nih.gov/health/echinacea. The information is succinct, noting that studies show that echinacea doesn't appear to prevent colds or other infections, nor does it shorten the duration of colds or flu.

For black cohosh, the site says studies are mixed for menopausal relief and notes that it has been linked with liver problems, though the site cautions that it's not clear whether black cohosh is truly to blame. As for glucosamine-chondroitin, the site includes the most recent and most credible study, the so-called GAIT trial, published in February in The New England Journal of Medicine, which showed that the remedy did not provide significant relief for osteoarthritis patients except for a subset with moderate-to-severe pain.

Another of my favorite sites -- because it is the most aggressively critical -- is www.worstpills.org, the creation of Public Citizen's Health Research Group in Washington, D.C., which takes no money from government or industry and relies on membership fees and product sales.

The site is thorough and put all three of my test supplements in the ``Do Not Use" category. Worstpills.org concludes, for instance, that ``there is no significant evidence that black cohosh alleviates menopausal symptoms." Among adverse effects, it cites two cases of liver transplants possibly linked to the supplement.

As for echinacea, the site concludes that there is ``no convincing evidence" that it reduces the frequency or severity of the common cold. On glucosamine-chondroitin, www.worstpills.org includes information from the GAIT trial.

Another good site is www.herbalgram.org (click on ``herbal information"), run by the Texas-based American Botanical Council and its chief guru, Mark Blumenthal. The council gets half its funding from the supplement/herbal industry and the other half from health professionals and researchers. Despite its industry backing, I find the site thorough, accurate, and fairly independent.

On black cohosh, herbalgram.org put out a special article in March after an Australian government agency warned that the substance was linked to liver toxicity. The site goes deep on black cohosh and notes that a leading black cohosh product, Remifemin, now carries a warning label about potential liver toxicity.

On echinacea, herbalgram.org has so much material it's tough to find a bottom line. It acknowledges the lack of efficacy for treating or preventing colds but points out that the most recent clinical trial was done with doses that were too low to be effective, Blumenthal said. The group did not evaluate glucosamine-chondroitin because it is not an herbal product.

Consumer Reports is another good site. A few weeks ago the group added a rating system for ``natural" remedies to its website -- www.consumerreports.org/mg/natural-medicine/ratings.htm. The massive amount of information in these ratings of 14,000 herbs, vitamins, and nutritional supplements comes directly from a respected source used by pharmacists and physicians, the Natural Medicines Comprehensive Database, which gets no industry funding and is supported by subscriptions from physicians and pharmacists.

For a fee, the Consumer Reports site provides a huge amount of detail about each product and possible interactions with other medications. Despite its vastness, it's easy to use. It goes easy on black cohosh, calling it ``possibly effective" for hot flashes, though it does note possible interactions with drugs like cisplatin, the cancer drug. A ``possibly effective" rating means there is some evidence of efficacy and possibly some negative evidence.

The site is also kind to echinacea and glucosamine-chondroitin, calling them both ``possibly effective." Echinacea, said the database editor, Dr. Phil Gregory, in an e-mail, is not effective in preventing colds and is only possibly effective in treating a cold. On glucosamine-chondroitin, he said that although the GAIT trial looked at the combination, most research examines glucosamine sulfate alone, and that does appear to be effective.

One other government site rates a mention. It's run by the FDA and lists dietary supplements on which the agency has issued safety alerts ( www.cfsan.fda.gov/~dms/ds-warn.html). It has issued no such alerts for black cohosh, echinacea, or glucosamine-chondroitin.

There are probably some useful, safe supplements out there. But the whole field of dietary and herbal supplements is basically faith-based medicine, so I'm glad there are some websites to check to make sure that while I think I'm doing myself some good, I'm not accidentally doing harm.

Judy Foreman is a freelance columnist who can be contacted at foreman@globe.com.