The Mayo Clinic's health information Web site has added a new section devoted to dietary supplements (www.mayoclinic.com; click on the "Drugs & Supplements" tab). It's one of the best free information sources on supplements available.

The Scoop Since dietary supplements -- herbs, vitamins, minerals and other substances that aren't quite foods and not quite drugs -- aren't closely regulated, information about their use and effects can be hard to find. Much information available to the public is of questionable accuracy and authored by enthusiasts or those who make and sell the products. The Mayo site offers a welcome counterpoint: detailed, dispassionate, scientifically rigorous entries on 86 supplements, including uses, dosage, safety, effectiveness, alternative names and history.

The Good Stuff Each supplement gets treated in depth, with plenty of footnotes. Each supplement is assigned a grade (A through F, based on available scientific evidence) rating its utility as a remedy for each of the health conditions it's associated with. Plus, it's a bargain: Getting the same information straight from the NSRC requires a $99 annual subscription.

The Downside You've got to know whether the substance you're researching is considered a supplement or a drug: Calcium, for instance, is included in the adjacent drug database, so you won't find it among the supplements. Once you get to the listing, you might have to scroll past a long list of specific product names before getting to the meat of the entry.

The Future Information about 19 more supplements is to be added by the end of the year; monthly updates will incorporate new data and findings.

-- Jennifer Huget