Glucosamine for Sports & Fitness

Some athletes say that glucosamine helps reduce joint pain.

For a long time, glucosamine dominated the market among supplements used to ease joint pain. Now, many practitioners prefer to use a combination of both glucosamine and chondroitin sulfate. Many have found this combination to be effective, particularly for runners, who tend to develop problems with their knees. Glucosamine and chondroitin sulfate are well absorbed by the molecules that make up cartilage. They are not available from food. It is not uncommon to have to take these supplements indefinitely to continue to experience relief.

Recent research has shown that the results of arthroscopic surgery for osteoarthritis in the knee is no different than that of placebo. This gives people further reason to at least give supplements, such as glucosamine sulfate, a try before enduring more invasive, expensive approaches.

Glucosamine sulfate, 1,500 mg per day, is effective for reducing joint pain caused by osteoarthritis according to most studies,^{1, 2, 3} Whether other forms of glucosamine, such as glucosamine hydrochloride, are as effective for joint pain as glucosamine sulfate is unclear at this time, but studies have found some benefits from the use of the hydrochloride form.^{4, 5} Other uses of glucosamine for sports and fitness, including prevention of joint pain or treatment of sports injuries, have not been studied.

GS may cause mild and reversible gastrointestinal side effects in some cases. In one trial, people with peptic ulcers and those taking diuretic drugs were more likely to experience such side effects.⁶

In a preliminary study, glucosamine supplements appeared to raise intraocular (eyeball) pressure by an average of about 3 mm Hg in people who had elevated intraocular pressure or a certain type of glaucoma (open-angle glaucoma).⁷ Therefore, individuals who have, or are at risk of developing, glaucoma should be monitored by a doctor if they wish to take glucosamine.

Animal research has raised the possibility that glucosamine could contribute to insulin resistance.^{8, 9} This effect might theoretically result from the ability of glucosamine to interfere with an enzyme needed to regulate blood sugar levels.¹⁰ However, available evidence does not suggest that taking glucosamine supplements will trigger or aggravate insulin resistance or high blood sugar.^{11, 12} Two large, 3-year controlled trials found that people taking GS had either slightly lower blood glucose levels or no change in blood sugar levels, compared with people taking placebo.^{13, 14} Until more is known, people taking glucosamine supplements for long periods may wish to have their blood sugar levels checked; people with diabetes should consult with a doctor before taking glucosamine and should have blood sugar levels monitored if they are taking glucosamine.

In 1999 the first case of an allergic reaction to oral GS was reported.¹⁵ Allergic reactions to this supplement appear to be rare.

Some GS is processed with sodium chloride (table salt), which is restricted in some diets (particularly for people with high blood pressure).

Glucosamine is not present in significant amounts in most diets. Supplemental sources are derived from the shells of shrimp, lobster, and crab, or may be synthesized.