Supplements for joint pain? Sounds good . . .

The product: All sorts of painkillers can offer comfort to people with arthritis, but none of them can give new life to worn-out joints. If you've squandered your personal supply of cartilage in your knees or hips, a truckload of Aleve won't bring it back. For decades, arthritis experts and patients have looked for remedies that do more than mask the pain.

This quest has turned glucosamine and chondroitin into superstars of the supplement industry. With U.S. sales about $1 billion annually, the compounds have a popularity to rival just about any prescription drug. Sold separately or together, they're available at drug stores, grocery stores and health food stores everywhere.

Glucosamine and chondroitin are natural substances -- types of sugars, actually -- that are abundant in human cartilage. Chondroitin is a complex substance that helps hold cartilage together. Glucosamine is a simpler compound that the body sometimes uses to make more chondroitin.

Once scientists discovered these substances, it didn't take a huge leap of logic to speculate that the pair might help treat or prevent osteoarthritis, the wear-and-tear variety of joint trouble that comes with age.

Anyone who wants to take glucosamine and chondroitin has plenty of options. Move Free Advanced Triple Strength tablets includes 1,500 milligrams of glucosamine and 200 milligramsof chondroitin. Take two tablets a day as directed, and you can expect to pay about $20 or more for a one-month supply. Osteo Bi-Flex combines 1,500 milligrams of glucosamine with 1,250 milligrams of a blend of chondroitin and MSM, another natural compound that the company says eases joint pain. At a recommended dose of three caplets a day, you can pay about $30 a month. Flexicose, a liquid supplement, contains 1,500 milligrams of glucosamine and a smattering of chondroitin and other ingredients per dose. You'd pay about $30 monthly.

Though glucosamine and chondroitin can be cooked up in a lab, most supplements use animal sources. Osteo Bi-Flex, for example, contains glucosamine from crustaceans (crabs, shrimp and crayfish) and chondroitin from cow cartilage.

The claims: Glucosamine and chondroitin are often promoted as safe, natural and effective alternatives for arthritis relief. The website for Osteo Bi-Flex claims that glucosamine and chondroitin are clinically proven to "improve joint health, comfort, range of motion and mobility." The Flexicose site says that the product will "help you get your life back because it works fantastically. Most users notice a significant drop in discomfort in only one to two weeks." The site also contends that Flexicose has a "whopping 98% success rate."