The Most Popular Supplements: Do They Work?

Glucosamine and Chondroitin sulfate
Source: Glucosamine is usually obtained from the shells of shrimp, lobster, and crabs. Chondroitin sulfate is from the cartilage of sharks and cattle. Synthetic versions can also be made in the laboratory.

They are sold individually and often in combination with each other.

Health claim: Arthritis pain, usually in the knees.

Does it work? Not for most people with mild pain who took part in the government's largest study of these supplements; dummy pills were just as effective.

The supplements did help some people with moderate to severe pain, but researchers said the group was too small to be convincing.

Another caveat: No supplements on the market were of high enough quality to be used in the study. Researchers ordered up their own batch that meet purity and potency standards.

Side effects: Minor, sometimes upset stomach during the six-month study.

Source material: National Center for Complementary and Alternative Medicine

Echinacea
Source: Coneflower.

Health claim: Mostly to treat or prevent colds.

Does it work?

2 government studies found it didn't work for treating colds in children or adults. Some other studies suggested possible benefit, and the head of the U.S. alternative medicine institute wants more study.

Most studies show echinacea doesn't prevent colds.

Side effects:

Usually none, but there can be stomach problems, rashes, increased asthma. People with ragweed and similar allergies can have allergic reactions.