Americans spend an estimated $20 billion a year on dietary supplements and "natural" remedies. Many of us are blissfully - even willfully - ignorant of the medicinal value, or lack thereof, in 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 are allowed to get - and stay - on the market unless clear evidence of harm is found.
We have been left largely to our own devices to figure out which alternative remedies work, and are safe, and which are pure snake oil.
Happily, a few reasonably trustworthy Web sites have sprung up enabling consumers to evaluate how much credible research there is (or isn't) for a particular supplement, how the "natural" remedy in question 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 are much less likely than prescription drugs to contain the ingredients listed on the labels.
To facilitate comparisons among my favorite sites, I have 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;
The combination of glucosamine-chondroitin, used to ease the pain of osteoarthritis.
It's hard to tell how solid the science is for 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 helpful and easy to use.
To check on echinacea, for instance, go to nccam.nih.gov/health/echinacea. The information is succinct, noting that studies show echinacea does not appear to prevent colds or other infections, nor does it shorten the lengths 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 to blame.
As for glucosamine-chondroitin, the site includes Glucosamine/chondroitin Arthritis Intervention Trial, or GAIT, study results showing the remedy did not provide significant relief for osteoarthritis patients.
Another of my favorite sites - because it is the most aggressively critical - is worstpills.org. It's the creation of Public Citizen's Health Research Group in Washington, 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 in medical literature of liver failures requiring transplants that were 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, worstpills.org includes information from the most recent and most credible study (the GAIT trial, published in February in the New England Journal of Medicine). It found a noncommercial form of the combination ineffective except in a subgroup of people with moderate to severe pain.
Another good site is herbal gram.org, run by the Texas-based American Botanical Council and its chief guru, Mark Blumenthal (click on "herbal information").
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 found the site thorough, accurate and fairly independent.
On black cohosh, herbal gram.org published an article in March after an Australian government agency warned that the substance was linked to liver toxicity. The site goes deep on black cohosh, noting that a leading black cohosh product, Remifemin, now carries a warning about potential liver toxicity.
On echinacea, herbalgram.org has so much material that it's tough to find a bottom line. It acknowledges the lack of efficacy for treating or preventing colds, but Blumenthal argues that the most recent clinical trial was conducted with doses that were too low to be effective. The group did not evaluate glucosamine-chondroitin because it is not an herbal product.
Consumer Reports magazine's Web site is another good one. A few weeks ago, the group added a rating system for "natural" remedies to its Web site. Visit consumerreports.org/mg/natural-medicine/ratings.htm.
The large 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 only by subscriptions from physicians and pharmacists.
The Consumer Reports site provides a lot of detail about each product and possible interactions with other medications. Even so, 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 medicines such as cisplatin, the cancer drug. A "possibly effective" rating means that there is some evidence of efficacy, and possibly some negative evidence.
The site is also kind to echinacea and glucosamine-chondroitin, calling them "possibly effective."
Echinacea, according to the database editor, Dr. Phil Gregory, is not effective in preventing colds and is possibly effective in treating an existing cold.
On glucosamine-chondroitin, he said that although the GAIT trial looked at the combination, most researchers have investigated 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 for 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.
My take on all this is that 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 am glad there are some Web sites to check with to make sure that while I think I am doing myself some good, I am not accidentally doing harm.
Send your questions to firstname.lastname@example.org.