Glucosamine is a simple molecule in the human body made from glucose and the amino acid glutamine. It is needed to produce other chemicals in the body, like glycosaminoglycans, that are involved in building cartilage and the thick fluid (synovial fluid) that surrounds and lubricates joints. Cartilage and synovial fluid cushions the joints, preventing them from rubbing together. As some people age, levels of glucosamine decrease causing the breakdown of cartilage and fluid which is believed to be the major factor leading to osteoarthritis.
There are different types of glucosamine, including glucosamine sulfate, glucosamine hydrochloride and N-acetyl-glucosamine. Most studies done have used glucosamine sulfate. It is believed that this dietary supplement is more effective than the others because of its sulfate content, which is also needed by the body to produce cartilage. There is some evidence that it may be helpful in the treatment of osteoarthritis. The following studies were done on patients with osteoarthritis of the knees.
According to one study involving 252 participants, those who took 500 milligrams of glucosamine sulfate three times a day had significant improvement in pain and movement compared to those who took a placebo after four weeks. Other double-blind, placebo-controlled studies have shown similar results. Side effects did not differ from either group.
Glucosamine has also been compared to non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDs like ibuprofen, which have analgesic and anti-inflammatory properties, only offer symptomatic relief. Not only do they not treat the root of the problem, they may actually worsen the condition. Glucosamine, on the other hand, has little direct anti-inflammatory effects and no direct pain-relieving effects but it appears to relieve symptoms in the long run by repairing cartilage. In addition, safety and side effects are significantly less and mild compared to NSAIDs.
In one study comparing 1,200 milligrams of ibuprofen with 1,500 milligrams of glucosamine sulfate, those who took ibuprofen had faster pain relief in the first two weeks, but those who took glucosamine had better improvement by week four. In another study comparing the same treatments, the glucosamine group had similar results in pain relief as the ibuprofen group at the end of two weeks, but only 6 percent of those taking glucosamine experienced side effects which were mild and 35 percent of those who took ibuprofen had side effects which were more significant.
Common side effects include heartburn, nausea, constipation and diarrhea. Uncommon side effects include headache, drowsiness and skin reactions.
If allergic to shellfish, caution should be taken when using products made from shellfish, even though glucosamine is derived from the shells (extracted from a carbohydrate) and not from the flesh (a protein) which is the allergen.
If you have a medical condition or are taking medications, consult your health care provider before taking.
Because there is not enough evidence regarding its safety for pregnant women or women breastfeeding, it should not be taken during these times.
Glucosamine is not recommended for children.
Some skin creams contain glucosamine, but there is no evidence that it can be absorbed through the skin. If pain relief is experienced from using these creams, it is believed that it is the other ingredients in the creams (like camphor) that are responsible for the effects.
Chondroitin is a larger molecule than glucosamine; therefore, the absorption rate through the intestinal tract is significantly lower (zero to 13 percent compared to 90 to 98 percent). The small amount of molecules that are absorbed are usually too large to be delivered to cartilage cells. According to research, some people with knee osteoarthritis have experienced some benefits from taking chondroitin, but the relief was normally modest or insignificant. Reported side effects include stomach pain, nausea, constipation, diarrhea, leg swelling, swollen eyelids, hair loss and irregular heartbeat. Chondroitin also comes in skin creams, but there is no evidence that it is absorbed through the skin. If you have a medical condition or are taking medications, consult your health care provider before taking. Pregnant women, breastfeeding moms and children should avoid use.
Combination of the Two
Does glucosamine and chondroitin work better if taken together? There is no evidence that taking supplements containing both ingredients is more beneficial. In fact, in rare cases, a combination of the two have been linked with high blood pressure, high heart rate and palpitations.
Although the above studies on glucosamine are quite impressive, some suggest it may not be helpful in repairing cartilage or relieving symptoms. When treating osteoarthritis, it is best to discuss your treatment plan with your health care provider. Also, it is important to consider other factors, such as eating a nutritious and well-balanced diet, exercising regularly and maintaining a healthy weight.
Michael Murray, N.D. and Joseph Pizzorno, N.D. "Encyclopedia of Natural Medicine" Prima Publishing 1998
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