The Health Benefits of Glucosamine

Glucosamine is a compound found naturally in the body, made from fructose 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.

Since glucosamine production slows with age, some people use glucosamine supplements to fight aging-related health conditions, such as osteoarthritis.

Taking glucosamine as a nutritional supplement is thought to keep osteoarthritis in check by restoring the body's glucosamine supply and repairing damaged cartilage.

In alternative medicine, proponents claim that glucosamine may help with the following health problems:

• Diabetes
• High cholesterol
• Inflammation
• Inflammatory bowel disease (such as ulcerative colitis)
• Osteoarthritis
• Rheumatoid arthritis
• Temporomandibular joint disorder

Glucosamine has been widely studied with inconclusive results. It may offer health benefits including a reduction in pain, although a 2018 review published in the journal Orthopedics suggests the benefits may be due to a placebo effect.

Here's a look at some of the key studies and their findings:

Glucosamine may be of benefit in the treatment of osteoarthritis, especially in the knee. Despite some very positive findings, there also a lot of evidence contradicting these claims.

An early report published in the Cochrane Database of Systematic Reviews concluded that some preparations of glucosamine may reduce pain and improve functioning in people with known osteoarthritis. The study analyzed 20 randomized controlled studies involving a total of 2,570 adults.

One of the largest glucosamine studies, sponsored by the National Institutes of Health (NIH), questioned these results. Called the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), the two-year study compared the effectiveness of glucosamine and chondroitin in 662 people with knee osteoarthritis and concluded that neither showed any benefit in relieving knee pain.

Subsequent studies have provided no clearer evidence of any benefits. However, some researchers still contend that glucosamine not only helps ease arthritis pain but also prevents cartilage loss.

According to a six-year study published in Arthritis Care & Research, cartilage loss appeared to be slowed in adults with knee osteoarthritis who had taken glucosamine and chondroitin for up to six years. The benefits appeared to be greater the longer the supplements are taken.

Further research is needed to make sense of these contradictions.

Glucosamine is possibly effective for temporomandibular joint (TMJ) osteoarthritis, according to a small study published in the Journal of Reseach in Pharmacy Practice. The trial involved 60 adults with TMJ who were given either glucosamine, ibuprofen, or a placebo for 90 days. Although glucosamine and ibuprofen were both more effective in relieving pain than a placebo, ibuprofen proved superior to glucosamine.

Glucosamine may not benefit people with chronic lower back pain and degenerative lumbar osteoarthritis, according to a 2010 study in the Journal of the American Medical Association. The six-month trial, involving 250 people with both conditions, concluded that glucosamine was no better than the placebo in providing arthritis pain relief.

Side effects of glucosamine are typically mild and include nausea, heartburn, diarrhea, and constipation. More serious side effects, including drowsiness, skin reactions, and headache are rare. Taking the supplements with food seems to ease side effects.

People with certain health conditions, including include asthma, diabetes, glaucoma, high cholesterol, and high blood pressure should not take glucosamine supplements without consulting a doctor.

People who are allergic to shellfish should check the label as many supplements are made from the shells of lobsters, shrimp, or crabs. 

Women who are pregnant or breastfeeding should not take glucosamine as there is not enough research to support its safe use. 

Stop taking glucosamine at least two weeks prior to scheduled surgery, as it may impact the body’s ability to regulate blood sugar. 

Glucosamine supplements should not be taken with the blood-thinning drug Coumadin (warfarin) as it may increase its effects and cause bruising and serious bleeding.

There is some evidence to suggest glucosamine may interfere with certain cancer drugs, known as topoisomerase II inhibitors. These include Adriamycin (doxorubicin), VePesid (etoposide), VM26 (teniposide), mitoxantrone, and daunorubicin. Glucosamine may hinder the effectiveness of these drugs.

There is no standard recommended dose for glucosamine. The supplement is typically sold in tablets and capsules and is often included with other supplements that may be effective for pain.

For osteoarthritis, the following doses have been studied:

• By mouth: 1,500 mg a day, taken either at once, in two doses of 750 mg, or in three doses of 500 mg
• Topically: A cream containing 30 mg/gram of glucosamine sulfate, 50 mg/gram of chondroitin sulfate, 140 mg/gram of chondroitin sulfate, 32 mg/gram of camphor, and 9 mg/gram of peppermint oil has been applied to the skin as needed for 8 weeks.
• By injection: 400 mg of glucosamine sulfate injected into the muscle twice weekly for 6 weeks

When selecting a brand of supplements, look for products that have been certified by Consumer Labs, The U.S. Pharmacopeial Convention, or NSF International. 

While the supplement is sold as glucosamine sulfate, glucosamine hydrochloride, and N-acetyl-glucosamine, most of the research showing benefits have used glucosamine sulfate.

Glucosamine is often combined with chondroitin sulfate, a molecule naturally present in cartilage. Chondroitin gives cartilage elasticity and is believed to prevent the destruction of cartilage by enzymes. In some cases, glucosamine is also combined with methylsulfonylmethane (MSM) in nutritional supplements.

Are there any food sources of glucosamine?

Glucosamine is made naturally in the body. There are no common food sources of it. While the glucosamine in supplements is often derived from the shells of shrimp, lobster, and crabs, eating shellfish shells is not recommended.

Is glucosamine safe for long-term use?

A 2016 study involving 1,593 people who had taken glucosamine and chondroitin for up to six years concluded that they were both safe and effective for long-term use.

Glucosamine may be of some benefit to people with osteoarthritis. It's important to note that health care providers often suggest a three-month trial of glucosamine and discontinuing it if there is no improvement after three months.

If you're considering the use of glucosamine in the treatment of any condition, talk to your doctor before starting your supplement regimen.