Thanks to lax federal laws, nutritional supplement companies don't have to worry about proving that their products are safe or effective before unleashing them on the marketplace. Here's an update on six high-profile supplement ingredients, based on information from the Natural Medicines Comprehensive Database. This database includes constantly updated published research on nutritional supplements and herbal remedies, including their safety, efficacy, and potential to interact with drugs or other supplements.

Coenzyme Q10 (CoQ10):This vitamin-like compound, also called ubiquinone, helps provide energy to cells and also works as an antioxidant. There's good, but not definitive, evidence that it may help prevent migraine headaches, slow the progression of Parkinson's disease, ameliorate the effects of muscular dystrophy, and lower blood pressure. Some studies have also found that when taken along with other medications, CoQ10 eases the symptoms of congestive heart failure. Safety problems appear to be few, even after prolonged use; some people find it upsets their digestive systems, and people on blood pressure medication should check with their doctors before trying it.

Pomegranate juice: The marketers who tout pomegranate juice as an antioxidant superpower are right: Ounce for ounce, it contains more antioxidant polyphenols than blueberries, cranberry juice, green tea, or red wine. Moreover, preliminary research suggests that the juice can help reduce systolic blood pressure, slow the progression of atherosclerosis, and possibly even reduce cholesterol. But there's a downside: Like grapefruit juice, pomegranate juice appears to interfere with an enzyme that's critical to the proper metabolism of many common medications. If you take any drugs regularly, check with your pharmacist or physician before trying pomegranate juice.

Black cohosh: This popular herbal hot flash remedy has performed inconsistently in clinical trials. Some have shown that it's modestly effective, while others have shown it's no better than a placebo. Though black cohosh has appeared safe in clinical studies lasting as long as six months, there have been several reports linking it to liver damage, in some cases severe enough to require liver transplants. It's not yet clear whether these cases actually involved black cohosh or some contaminant or unlabeled ingredient. In the meantime, anyone with liver disease should avoid black cohosh. So should anyone on one of the many medications that can potentially harm the liver, including acetaminophen (Tylenol), erythromycin, lovastatin (Mevacor), simvastatin (Zocor), and methyldopa (Aldomet).

• "Safe" fat burners:
The Food and Drug Administration ban on ephedra-based weight-loss products does not mean you can take "thermogenic" or "fat-burning" supplements without fear of dangerous side effects, despite what their promoters claim.

One product advertises itself as "the most effective and safe thermogenic weight-control formula available." It's anything but safe. One of its ingredients, 5-hydroxytryptophan (5-HTP), has documented side effects including severe gastrointestinal symptoms and pain and inflammation of the muscles, joints, and skin. The supplement also contains citrus aurantium or bitter orange, a chemical cousin of ephedra that's thought to be especially risky when consumed along with caffeine—which the product also contains in abundance in the form of straight caffeine and caffeine-containing green tea.

Another product calls itself "the MOST effective approach to losing weight ever developed." One of its ingredients, kelp, is unsafe because of its potentially high concentration of iodine, and also its frequent contamination with arsenic.


• Yohimbe-free erectile dysfunction supplements:
Though it's still legal to sell and even available as a prescription drug, yohimbe's well-deserved reputation for riskiness has spread far enough that savvy supplement marketers are using its absence to promote their impotence remedies.

"We chose not to use [yohimbe] … because your safety always is first," says one product's Web site. The makers of another dismiss yohimbe for its "dangerous side effects." Reassuring words, except that a main ingredient in both of those products is horny goat weed (epimedium), which is itself unsafe because it can cause dizziness, vomiting, spasms, and breathing problems. There's also no evidence that it does anything to improve a man's sexual function.


• Noni juice:
This juice, from a Polynesian tropical fruit called morinda, has rocketed up the supplement sales charts in the past five years as a purported all-purpose cellular performance booster. Web sites attribute its wondrous effects to a constituent called "proxeronine." The reality: Proxeronine is not a known or identified chemical compound, nor is there any reliable published clinical research on the health-enhancing effects of morinda. But it does have a significant quantity of potassium, which makes it problematic for anyone with kidney dysfunction or who takes ACE inhibitors (Altace, Capoten, Lotensin, Prinivil, Vasotec) or angiotensin-receptor blockers (Atacand, Avapro, Cozaar, Micardis, Teveten). And there have been several published reports of people who suffered liver damage after drinking the juice.