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The mainstream medical community historically has viewed alternative therapies with skepticism, but reputable scientific studies reveal that glucosamine and chondroitin really can help those who suffer from joint pain caused by osteoarthritis.

Glowing reports from patients and a host of scientific research support the effectiveness of the natural remedies, which first became available over the counter at health stores, and have become America's top-selling joint supplements. They're so popular that they are now sold over the counter in drug stores, supermarkets, discount stores and even warehouse stores for as little as $7.95 for a bottle of 100 capsules.

More than 40 million Americans have osteoarthritis — a degenerative "wear and tear" joint disease characterized by loss of cartilage, the shock-absorbing gel-like material between the joints. Local tenderness, swelling and loss of mobility are signs of the presence of osteoarthritis, which increases dramatically after age 50. Weight-bearing joints, such as knees and hips, as well as the spine and hands, are typically affected.

Glucosamine sulfate, which has been the subject of more than 300 scientific studies, is made of crab shells and other natural marine products. Chondroitin is made from cow cartilage. Glucosamine in its natural form stimulates cells that make cartilage while chondroitin sulfate is said to block enzymes that break down old cartilage.

An analysis of the two supplements, published in the Journal of the American Medical Association on March 15, 2000, reported a moderate effect on pain and mobility with glucosamine taken alone and a large positive effect for chondroitin. In Europe, the supplements have been widely prescribed and found to be effective for more than a decade.

In its own analysis of glucosamine and chondroitin, Consumer Reports said comparison studies reveal that the supplements are "at least as effective as Ibuprofen (also marketed as Advil and Motrin IB)." It also reported that there is "some evidence that the supplements may actually slow the progression of cartilage loss in affected joints." However, Consumer Reports cautioned that the supplements may need to be taken for more than a month for full therapeutic effect.

Consumer Reports says the short-term safety profile "appears to be good," but that studies of long-term adverse effects are underway, particularly in regard to drug interactions for people on blood-thinning medications and about harmful effects on insulin resistance.

However, Dr. Michael Murray, a leading naturopath, claims that 98 percent of glucosamine sulfate is absorbed intact and has "absolutely no effect on blood sugar levels." He also says there have been "no reports of any adverse drug interactions with glucosamine sulfate."

Murray is not convinced that taking glucosamine in combination with chondroitin makes it more effective. He also cautions that glucosamine sulfate is the "preferred" and most easily absorbed form of glucosamine (some over-the-counter preparations feature other forms of glucosamine, such as glucosamine hydrochloride and N-acetyl-glucosamine, which he says are not as effective). He advises taking 500 mg of glucosamine sulfate three times a day for best results. Those who weigh more than 200 pounds may need higher dosages, based on weight.

As for people who are allergic to sulfur (such as sulfite food additives and sulfa drugs), Murray says no allergic reactions to glucosamine sulfate have been reported. He says glucosamine sulfate is well tolerated and nontoxic.

Nonsteroidal anti-inflammatory drugs are the conventional treatment for osteoarthritis, but Murray warns that NSAIDs, which include aspirin and ibuprofen, may actually accelerate joint destruction because they suppress the body's natural ability to produce anti-inflammatory enzymes and can also cause gastrointestinal upset.

Dr. Jason Theodosakis, author of the best-selling book "The Arthritis Cure," suggests that ginger and vitamin B-6 (100 mg twice a day) may also help with arthritis pain. He mentions boswellia serrata (an extract of the herb commonly known as frankincense) as helpful. Boswellia is currently available in health food stores and may be found combined with glucosamine in natural supplements designed to increase mobility and ease joint pain.

MSM (methyl sulfonyl methane) is an organic sulfur that Dr. Earl Mindell, author of many books on natural remedies and wellness, says can provide the body with the necessary raw materials to create healthy new cells, when taken in conjunction with vitamins and amino acids.

Before trying any of these natural supplements, it's best to consult your personal physician.