Glucosamine is an amino sugar that occurs naturally in the body. This one-molecule substance consists of glucose and a hydrogen and nitrogen amine. Amino sugars are different from other body sugars, as they form part of carbohydrates. Their function is also different as they are not a source of energy, but rather are included in body tissue structure. Therefore, glucosamine plays a role in forming and maintaining the body's tissues—for example, constructing nails, skin, eyes, bones, ligaments, tendons, heart valves, discharging mucus from the respiratory system, digestive system, and urinary tract. Glucosamine helps blend sulfur into the cartilage. When people grow older, their bodies may lose the capacity to make enough glucosamine, so the cartilage in such weight-bearing joints as the hips, knees, and hands is destroyed. The remaining cartilage then hardens and forms bone spurs , causing pain , deformed joints, and limited joint movement.
Glucosamine is not readily available from any primary food source. Commercial preparations of glucosamine are derived from chitin, which is a substance found in the outer covering of such shellfish as lobster, crab, and shrimp, as well as in such animal connective tissues as the marrow of chicken bones. Commercially prepared glucosamine comes in three formats: glucosamine sulfate, glucosamine hydrochloride, and N-acetyl-glucosamine (NAG).
Glucosamine works to stimulate joint function and repair. It is most effective in treating osteoarthritis (OA), the most prevalent type of arthritis. A number of studies over the last 20 years have shown that glucosamine is helpful in relieving arthritis symptoms. For example, a 1982 clinical study compared usage of the NSAID ibuprofen with glucosamine sulfate, for osteoarthritis of the knee. During the first two weeks, ibuprofen decreased pain faster, but by the fourth week the glucosamine group was well ahead in pain relief. The overall results showed 44% of the glucosamine group had pain relief compared to 15% for ibuprofen. A British study published in 2002 reported similar findings regarding the effectiveness of glucosamine in relieving pain associated with arthritis. A team of Japanese researchers has suggested that glucosamine relieves the pain of arthritis by suppressing the functions of neutrophils, which are white blood cells that contribute to the joint inflammation found in arthritis. Other researchers think that the sulfur content of glucosamine contributes to its healing properties.
Several studies have concluded that over-the-counter preparations of glucosamine sulfate are safe for long-term treatment of osteoarthritis. These are readily available in the dietary supplement sections of most pharmacies. Glucosamine preparations are sometimes classified as nutraceuticals, a term used to refer to foods or food ingredients that are thought to provide medical or health benefits.
Harvard Medical School recently conducted a somewhat unorthodox study in which patients scheduled for hip surgery were given ground chicken bone supplements. After two weeks of taking these supplements, their pain was reduced considerably.
Glucosamine supplements can also aid in treating sports injuries, bursitis , food and respiratory allergies, asthma, osteoporosis, tendinitis, vaginitis , some skin problems, and candidiasis.
As of 2002, however, updated guidelines issued by the American College of Rheumatology for the treatment of osteoarthritis continued to list glucosamine along with acupuncture and electromagnetic therapy as treatments that are still under investigation for treating OA.
Although commercially prepared glucosamine comes in three formats: glucosamine sulfate, glucosamine hydrochloride, and N-acetyl-glucosamine (NAG), not all three work the same. There are also differing opinions on which is better.
One claim states that glucosamine hydrochloride works 50% better than glucosamine sulfate because hydrocholoride is the main stomach acid helping the digestive system to put more active ingredients into the body. Another prefers glucosamine sulfate because of its high absorption rate of 98% documented in human studies and its sulfur content. Studies as far back as the 1930s show that people with arthritis usually have low levels of sulfur.
N-acetyl-glucosamine (NAG) can be beneficial to individuals with Crohn's disease or ulcerative colitis. Individuals with these diseases cannot change glucosamine to NAG as fast as those without the diseases. In one study, cells from patients' intestines were soaked in a solution with a 10:1 ratio of radioactive NAG to glucosamine. These cells consolidated more NAG than did the cells from the intestines of patients without Crohn's disease or ulcerative colitis.
Glucosamine is also sold mixed in formulas with devil's claw , pregnenolone, methylsulfonylmethane (MSM ), and chondroitin sulfate. Chondroitin sulfate is one of the main glycosaminoglycans (GAGs) that is contained in shark cartilage and sea cucumber. Although studies show that chondroitin sulfate has benefits, it is hard to absorb because it contains large molecules.
Further confusion can arise because glucosamine is classified and sold as a dietary supplement, meaning it has not gone through the FDA approval process. As with any dietary supplement, patients with arthritis who are considering glucosamine formulations should consult their healthcare practitioner.
The standard dosage is 500 mg three times daily. Obese people may need to take higher dosages based on their weight.
Diabetics should be aware that glucosamine contains the sugar glucose, and can raise blood sugar and insulin levels. A 2000 study of 15 nondiabetic patients at the Los Angeles College of Chiropractic and MetaResponse Science showed that those who took 1,500 mg of glucosamine a day for 12 weeks had raised insulin levels. The conclusion was that the insulin rise would probably be more in diabetics. However, researchers cautioned diabetics there is no need to discard their glucosamine supplements as more controlled studies are required.
Despite the concern regarding the use of glucosamine sulfate in persons with allergies to the sulfa drugs or the sulfite additives in food, sulfur itself is a necessary mineral and human blood contains large amounts of sulfur's sulfate form. Studies show that glucosamine sulfate is safe for long term use to treat osteoarthritis, with the exception of medical conditions listed above and below.
High dosages of glucosamine may cause gastric problems, nausea, diarrhea, indigestion , and heart-burn . Glucosamine should be taken with meals to help avoid these problems
Glucosamine should not be taken with heart medications or insulin. Those taking diuretics may require higher amounts of glucosamine on a daily basis.
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"Glucosamine: Is it a beneficial arthritis treatment?" <http://www.onhealth.com>.
Rebecca J. Frey, PhD
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