Dear Alice,

Is it true that taking a glucosamine supplement might improve joint strength and mobility? What exactly is glucosamine? Are there any side effects of taking glucosamine? And, if it is a good idea to take it, what dosage is recommended?

Many thanks.

Dear Reader,

Glucosamine is a monosaccharide or simple sugar that occurs naturally in the body, and the compounds glucosamine sulfate and glucosamine HCL (hydrochloride) are found in shellfish. Glucosamine, a combination of glucose and glutamine, contributes to the formation of cartilage. Cartilage cushions joints. As wear and tear occurs, the body's ability to replace cartilage slows or ceases, resulting in osteoarthritis.

In European countries for years, medicinal glucosamine has been prescribed for arthritis. In the United States, clinical studies on glucosamine's (both Sulfate and HCL forms) effectiveness at easing joint discomfort began in 1980 and it has more recently appeared on the U.S. over-the-counter (OTC) market as a dietary supplement. Several studies have proven it as being more effective in the treatment of arthritis, especially osteoarthritis, than non-steroidal anti-inflammatory drugs (NSAIDS), such as ibuprofen or aspirin. Overall, studies have shown that glucosamine helps slow degeneration of cartilage and relieves pain. In addition, glucosamine has anti-inflammatory and antioxidant factors. Glucosamine also has fewer side effects compared to NSAIDS, which can erode stomach lining, leading to gastro-intestinal bleeding.

For osteoarthritis treatment, the usual daily dose is 1,500 milligrams, taken all at once or divided into 500 mg doses, three times a day. People weighing more than 200 pounds are advised to increase their dosage to 2,000 mg/day.

In a 3-year study using 1,500 mgs of glucosamine daily, no severe side effects were found. The most common side effect was mild gastrointestinal discomfort. Other reported short-term side effects include drowsiness, skin reactions, and headache. Because part of the glucosamine compound is a sugar (monosaccharide), there is some question as to whether supplementation may not be indicated for people with diabetes. Some studies have shown an increase in short-term insulin resistance, but in longer-term use, no change in blood sugar has been noted. Pre-diabetics and people with diabetes interested in using the glucosamine need to have their health care provider monitor their blood sugar during the first few weeks of using this supplement.

Toxicity studies have been done for the general public, but data is lacking on the effects of glucosamine supplementation in children and pregnant and lactating women. Therefore, although glucosamine has not exhibited toxicity at 1,500 mgs or higher, these special populations are not encouraged to take it.

People who are allergic or sensitive to sulfa drugs or sulfite-containing food additives can safely take glucosamine sulfate because sulfur is an essential nutrient that is naturally present in the body. Glucosamine is manufactured from the chitin exoskeleton of shellfish (lobster, crab, and shrimp), and although the pharmaceutical grade of glucosamine is generally devoid of shellfish contaminants, people with severe shellfish allergies need to exercise caution when taking this supplement.

Glucosamine has been coupled with chondroitin sulfate in some supplements. While it has been demonstrated that glucosamine can be absorbed and attaches to cartilage, many researchers believe that chondroitin sulfate cannot be absorbed in supplement form. For this reason, it is suggested to take glucosamine supplements without chondroitin. Also avoid glucosamine supplements that add NaCl (sodium chloride or table salt), KCl (potassium chloride), or include potassium in the ingredient list. In addition, NAG (N-Acetylglucosamine or N-Acetyl-D-Glucosamine) is another rarer form of glucosamine that needs to be avoided due to its ineffectiveness and expense. Unless the label states glucosamine sulfate or glucosamine HCL, you may be getting an inferior product.

Because glucosamine is classified as a natural health product, it is readily available OTC, and is held to a lower standard of purity and potency than prescription medications. A recent independent study revealed that up to 1/3 of glucosamine products did not contain the amount of glucosamine stated on the label. Supplements need to have a manufacturer's certificate of analysis or a third party true-to-label claim document to verify the purity and potency of the products.


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