What is glucosamine, and how does it repair joints?
Veterinary medicine has been using glucosamine successfully for decades to replace lost cartilage
in the joints of animals. The reason that doctors have not been doing this for human patients is
yet another topic outside the scope of this article.
Essentially, the cushion in our joints (cartilage) continually wears down and regrows in healthy joints.
In old, worn joints, the cartilage wears away faster than the body can replace it, causing a bone-on-bone
condition, necessitating surgical joint replacement.
Glucosamine (combined with chondroitin) promotes faster regrowth of cartilage, thus restoring
joint health.
Why do I need chondroitin along with glucosamine?
Chondroitin is believed to enhance the shock-absorbing properties of collagen and block enzymes
that break down cartilage. Studies are being done to evaluate the ability of chondroitin to reverse cartilage loss.
It generally takes two to four months to work completely.
Two large studies that evaluated data from about a dozen studies showed significant improvement in pain and
inflammation and improved joint function. Some people taking chondroitin are able to decrease NSAID dosage.
What is glucosamine made from? How do we know it really works?
Other names for glucosamine are: glucosamine sulfate, glucosamine sulphate, glucosamine hydrochloride,
N-acetyl glucosamine, chitosamine.
Glucosamine is a compound found naturally in the body, made from glucose and the amino acid glutamine. Glucosamine
is needed to produce glycosaminoglycan, a molecule used in the formation and repair of cartilage and other body tissues.
Production of glucosamine slows with age.
Glucosamine is available as a nutritional supplement in health food stores and many drug stores. Glucosamine
supplements are manufactured from chitin, a substance found in the shells of shrimp, crab, lobster, and other
sea creatures. In additional to nutritional supplements, glucosamine is also used in sports drinks and in cosmetics.
Since the body's natural glucosamine is used to make and repair joint cartilage, taking glucosamine as a nutritional
supplement is thought to help repair damaged cartilage by augmenting the body's supply of glucosamine.
There is promising evidence that glucosamine may reduce pain symptoms of knee osteoarthritis and possibly slow the
progression of osteoarthritis. For example, a study published in the journal Archives of Internal Medicine examined
people with osteoarthritis over three years. Researchers assessed pain and structural improvements seen on x-ray.
They gave 202 people with mild to moderate osteoarthritis 1,500 mg of glucosamine sulfate a day or a placebo.
At the end of the study, researchers found that glucosamine slowed the progression of knee osteoarthritis compared
to the placebo. People in the glucosamine group had a significant reduction in pain and stiffness. On x-ray, there
was no average change or narrowing of joint spaces in the knees (a sign of deterioration) of the glucosamine group.
In contrast, joint spaces of participants taking the placebo narrowed over the three years.
One of the largest studies on glucosamine for osteoarthritis was a 6-month study sponsored by the National Institutes
of Health. Called GAIT, the study compared the effectiveness of glucosamine hydrochloride (HCL), chondroitin sulfate,
a combination of glucosamine and chondroitin sulfate, the drug celecoxib (Celebrex), or a placebo in people with
knee osteoarthritis.
Glucosamine or chondroitin alone or in combination didn't reduce pain in the overall group, although people in the
study with moderate-to-severe knee pain were more likely to respond to glucosamine.
One major drawback of the GAIT Trial was that glucosamine hydrochloride was used rather than the more widely used
and researched glucosamine sulfate. A recent analysis of previous studies, including the GAIT Trial, concluded that
glucosamine hydrochloride was not effective. The analysis also found that studies on glucosamine sulfate were too
different from one another and were not as well-designed as they should be, so they could not properly draw a
conclusion. More research is needed.
Still, health care providers often suggest a three month trial of glucosamine and discontinuing it if there is
no improvement after three months. A typical dose for osteoarthritis is 1,500 mg of glucosamine sulfate each day.
Other Conditions Benefitting from Glucosamine:
Other conditions for which glucosamine is used include rheumatoid arthritis, inflammatory bowel disease (Crohn's
disease and ulcerative colitis), chronic venous insufficiency, and skin conditions, although further evidence is needed.
Side Effects and Safety of Glucosamine:
Most studies involving humans have found that short-term use of glucosamine is well-tolerated. Side effects may
include drowsiness, headache, insomnia, and mild and temporary digestive complaints such as abdominal pain, poor
appetite, nausea, heartburn, constipation, diarrhea, and vomiting. In rare human cases, the combination of
glucosamine and chondroitin has been linked with temporarily elevated blood pressure and heart rate and palpitations.
Since glucosamine supplements may be made from shellfish, people with allergies to shellfish should avoid
glucosamine unless it has been confirmed that it is from a non-shellfish source. The source of glucosamine
is not required to be printed on the label, so it may require a phone call to the manufacturer.
There is some evidence suggesting that glucosamine, in doses used to treat osteoarthritis, may worsen blood sugar,
insulin, and/or hemoglobin A1c (a test that measures how well blood sugar has been controlled during the previous
three months) levels in people with diabetes or insulin resistance.
Theoretically, glucosamine may increase the risk of bleeding. People with bleeding disorders, those taking
anti-clotting or anti-platelet medication, such as warfarin, clopidogrel, and Ticlid, or people taking supplements
that may increase the risk of bleeding, such as garlic, ginkgo, vitamin E, or red clover, should not take
glucosamine unless under the supervision of a healthcare provider.
The safety of glucosamine in pregnant or nursing women isn't known.
