OK, I ADMIT IT. I bought a bottle of Juvenon Energy Formula. It cost $45, including shipping, for just a month's worth of pills. The price seemed a little steep, but the manufacturer's Web site promises that its product will "promote healthy cells" and "boost energy levels." And goodness knows, as the 40-something working mom of a wiggly 8-year-old boy, I could use a little extra motivation.

Promises of more pep and rejuvenated cells would not ordinarily be enough to induce me, a consumer who generally eschews all pills except for vitamins, to part with my money -- much less ingest a supplement. I bought it because Juvenon Energy Formula is the brainchild of Bruce Ames, Ph.D., winner of the National Medal of Science and author of more than 450 scientific papers. Ames, a renowned cell biologist at the University of California, Berkeley, invented the test that determines the cancer-causing risks of chemicals. He's also the undisputed expert on free radicals, the highly reactive molecules that ravage the insides of cells and are now thought to be a cause of such diseases as cancer, Parkinson's, maybe even Alzheimer's. His pills contain a combination of two naturally occurring substances that mop up and limit the formation of free radicals and may slow down cell aging.

So why am I leery of most other dietary supplements? Here's a better question: How could I not be? In the past 5 years of my journalism career, I've interviewed more than a dozen people who have suffered strokes, organ damage, or uncontrolled bleeding after taking supplements. I've also sat with the grieving families of supplement users who died. One woman lost her transplanted kidney because she was mildly depressed and took some St.-John's-wort, which interfered with her body's ability to absorb an antirejection drug. Another wound up dead after taking a product containing ephedra, the controversial Chinese herb, in hopes of losing 20 pounds.

Maybe my view of supplements is biased after years of investigating their dangers. But I can't help thinking that the people who have been harmed by them deserved better from regulators who are supposed to protect the public. In fact, a measure of skepticism seems especially appropriate right now, as we approach the 10th anniversary of the Dietary Supplement Health and Education Act, or DSHEA as it's known in Washington, D.C. Passed in October 1994, that law changed the way the U.S. Food and Drug Administration (FDA) deals with these products -- and touched off the supplement explosion.

In the years since DSHEA's passage, supplement sales are thought to have quadrupled by some estimates. Roughly 29,000 items are now available, and about 1,000 new ones surface each year. But to my mind, DSHEA has gone a long way toward misinforming consumers about the safety and effectiveness of these remedies. Name a condition from Alzheimer's disease to zinc deficiency, and, largely because of DSHEA, chances are good that there is a vitamin, mineral, herb, amino acid, pollen, hormone, or extract of some animal part of another that promises -- with little or no scientific proof -- to relieve symptoms and return you to glowing good health.

The lure of supplements certainly has many sources, at least one of which is people's growing frustration with Western medicine. Patients are sick and tired of going to doctors who always seem to be in a rush, who have the bedside manner of a porcupine, and who are too busy handing out prescriptions and ordering more tests to offer anything that resembles health care. At the same time, consumers are concerned about the serious side effects of many prescription and over-the-counter drugs.

For many, buying dietary supplements undoubtedly feels like a way to take back some measure of control over their health. As an herbal-enthusiast friend told me recently, "Getting my medicine at the health-food store is my way of saying "It's my body; I'll do what I want with it.'" And huge swaths of the population apparently agree with her.

According to a new government poll of 31,000 adults nationwide, 25 percent report that they've used herbal remedies and other specialty products. A Harris survey, paid for by the supplement industry, found that more than half of Americans believe supplements offer benefits that they can't get from prescription or OTC medicines.

Still, I find it astonishing that the same people who are worried about side effects from prescription drugs will down pills and powders containing ingredients like elk velvet and cow brain without a second thought. I mean, don't consumers read the stories about people who have been harmed by androstenedione, comfrey, ephedra, and kava, to name just a few substances that have been linked to such serious reactions as liver damage and stroke? There's got to be a better explanation for why millions upon millions of Americans would plunk down money for products that might not work, or worse, that could harm or kill them.

The answer, I think, is that many have been lulled into believing that their government actually regulates dietary supplements. In a 2002 Harris Poll of 1,010 adults, 59 percent said they believed supplements must be approved by a government agency before they are marketed to the public. (Not true.) A little more than half of those polled said that supplement makers can't make safety claims without solid scientific evidence. (They can.) More than two-thirds said the government requires that manufacturers post warning labels on their products listing any dangerous side effects. (It doesn't.) In other words, Americans think they're being protected when they are not.

And that is DSHEA's fault. The law was intended to clarify the sometimes-murky rules that the FDA once used to govern supplements, which years ago consisted mostly of vitamins and minerals and a few herbal preparations. Instead, DSHEA effectively tossed those rules out, flinging open the door for just about anything that isn't a synthetically derived drug or a protein produced through biotechnology.

As long as the marketers don't actually lie on labels or swear that their products cure a specific disease, like Alzheimer's or AIDS, DSHEA permits them to say whatever else they want -- and they do. "Set your love life on fire!" and "Turn your body into a fat-burning furnace!" are a couple of the more outrageous claims, but even the more reasonable-sounding promises aren't necessarily based on solid evidence. One manufacturer says the hormone DHEA, for example, will slow the aging process, when in fact research confirms no such thing.

The majority of dietary supplements (other than vitamins and minerals) have never been subjected to any kind of rigorous scientific scrutiny. Only a fraction have been tested in gold-standard clinical trials, which involve giving one group of human subjects a particular product and another group a placebo, and then looking at which group gets better.

A handful of those products have turned out to be mildly beneficial. Saw palmetto, for instance, may help relieve symptoms of benign prostate enlargement, a condition that affects many older men. And ginkgo biloba, touted as a memory enhancer, may improve recall ever so slightly for people with Alzheimer's -- but it's not clear that there's a benefit for anybody else. Other supplements may not hold the curative powers their marketers would have you believe. But who knows? Good studies simply haven't been done.

Even manufacturing standards, meant to ensure that products are not contaminated and contain no material other than what's listed on the label, are voluntary. That hardly puts one's mind at ease.

The little-known risks of supplements are especially frightening. For example, androstenedione (a.k.a. "andro"), an athletic-performance enhancer, has been linked to serious side effects: impotence and shrinking testicles in men, a heightened risk of breast cancer and blood clots in women. And although some research shows that most supplements pose little risk when combined with prescription medications, other findings are worrisome. St.-John's-wort can block the action of birth control pills and AIDS drugs; it also renders the antirejection drug cyclosporine ineffective. Ginkgo biloba interferes with blood clotting, making it potentially life-threatening for anyone taking anticoagulants, such as warfarin, or other medicines that thin the blood, like aspirin. And the herb Echinacea should not be taken by anybody who has an autoimmune disease.

In most cases, the dangerous combinations and side effects come to light only when alert doctors put two and two together and figure out that a patient's complaint is associated with using a supplement. Manufacturers are not required by DSHEA to test for adverse reactions ahead of time. They don't even have to turn over reports of side effects to the FDA. (Pharmaceutical companies, by contrast, are required by law to provide such reports.)

This regulatory loophole has allowed manufacturers to sit on information that might have saved lives. A case in point: Metabolife International, the San Diego -- based company that used to make the weight-loss nostrum Metabolife 356, withheld evidence for years that its product was causing serious harm, including death, despite repeated requests by a member of Congress.

Indeed, the story of Metabolife 356 -- among other products containing the herb ephedra -- should give any would-be supplement taker pause, because it shows just how powerless the FDA is when it comes to ensuring consumer safety. Ephedra, or ma huang as the plant is known in China, contains a number of naturally occurring stimulants, all of them chemical cousins of amphetamines, which are well-known for raising the risks of stroke and heart attack.

By 1999, the year I began working on my first supplement story, the FDA had already received about 900 reports of serious reactions -- including strokes, heart attacks, and deaths -- associated with the use of ephedra products. My article focused on the case of Anne Marie Capati, a 37-year-old mother who collapsed from a massive stroke after taking Thermadrene, an ephedra supplement marketed to bodybuilders as a weight-loss aid. Her husband and parents watched her die in the emergency room as doctors tried desperately to revive her.

If the FDA had its way, ephedra would have been yanked from the market long before Capati took her first pill. But for years the agency hadn't even been able to compel supplement makers to include stiff warnings on labels. Manufacturers beat back a 1997 FDA proposal that called for beefed-up warning language by persuading key members of Congress that their products were safe and that regulators were a bunch of jackbooted antibusiness bureaucrats.

The ephedra industry already had many allies on Capitol Hill, but it gained even more friends by pouring more than $3 million into campaign coffers between 1994 and 2002, according to the Center for Responsive Politics. By 2002, Sen. Richard Durbin (D-Illinois) told me that legislators were afraid to cross this formidable lobby.

It took the death of a celebrity -- Steve Bechler, a Baltimore Orioles pitcher who collapsed from heatstroke during spring training in February 2003 after taking an ephedra product -- for Congress to finally allow the FDA to do what it should have done years ago: Ban supplements made with the herb. The measure went into effect more than a year after Bechler died.

Clearly, DSHEA is a broken law. Still, I'm not willing to argue that the sky is falling. Congress and even some segments of the supplement industry finally have begun to realize the law needs fixing. Earlier this year, a report from the Institute of Medicine urged Congress to give the FDA authority to require that supplement manufacturers turn over reports of adverse effects. That suggestion was supported by the American Herbal Products Association, an industry group.

Congress is now considering legislation that would strengthen DSHEA, giving the Secretary of Health and Human Services greater power to recall products, for example. And the FDA has already announced that it is developing regulations for good manufacturing practices. Eventually, that move should help protect consumers from dietary supplements that contain impurities or contaminants.

This is good news, to be sure, although how effective the FDA will be in curbing the most hazardous supplements remains to be seen. What is needed now, more than anything, is good science -- and consumers who demand it. The National Institutes of Health's National Center for Complementary and Alternative Medicine has launched dozens of clinical trials in recent years, testing treatments ranging from acupuncture to relieve diarrhea in AIDS patients to vitamin E for people with heart disease. But more could -- and should -- be done.

Why not contact your congressional representative, even your senators, and tell them you insist on solid research and reasonable regulations that make you safer? Tell them, for example, that if supplement makers can rake in the cash, at the very least they should be required by law to plow some of their take into testing new products for safety before putting them on the market. That's what 9 out of 10 consumers would like, according to a national survey released in June by Consumers Union, the nonprofit organization that publishes Consumer Reports.

I'd like that, too. Lack of testing is one of the many reasons I'm skittish about taking most dietary supplements -- and willing to try Bruce Ames' Juvenon Energy Formula. Maybe it can fill me with vim and vigor, and maybe it can't, but at least Ames and his partners relied on previous human studies showing that the chemicals in their formula were safe before they started selling it. The scientists are now putting Juvenon through rigorous clinical trials to find out if it actually works.

If their research pans out, I might just buy another bottle.