Now you don't have to depend on the store clerk at the health food store to help you compare and choose a dietary supplement. A free online database launched this week let's you check the label and browse the ingredients and claims of brand name products, and find out what's included in those "proprietary blends".

The easy-to-use National Institutes of Health's Dietary Supplement Label Database lets you search by supplement ingredient or by product name. We searched vitamin D, for example, and found 342 products. Advanced Search then helped us further zero-in on the supplements of interest. Search results--including label images--can be saved to a spreadsheet, which can be handy for the (very necessary) discussion with your doctor or pharmacist about what you're taking.

You can also search supplement products for label warnings. Companies can provide warning labels if they choose, but the Food and Drug Administration doesn't require them on supplements, except that those that contain iron must warn about accidental overdosing and fatal poisoning in children. For each supplement, contact information is included, in case you want to get in touch with the product manufacturer or distributor.

The NIH database now contains 15,721 of the estimated 55,000 dietary supplements on the U.S. market. Plans call for data from 1,000 new labels to be added monthly, and existing records to be updated annually.