Glucosamine plays a vital role in building and repairing cartilage. For that reason many people take glucosamine supplements in the hope of boosting their joint health.
Glucosamine is a natural sugar that exists in the fluid around the joints, as well as in animal bones, bone marrow, shellfish, and fungi.
The glucosamine in supplements usually comes from the shells of shellfish, though there is also a synthetic form.
According to the National Center for Complementary and Integrative Health, around 2.6% of adults in the United States used supplements of glucosamine, chondroitin, or both in 2012. Chondroitin is similar to glucosamine and also occurs naturally in joints.
These were the second most popular dietary supplement after fish oil and other types of omega-3 fatty acids.
What is glucosamine?
Glucosamine supplements typically come as tablets or capsules, but they are also available as injections.
Also, there are various types of glucosamine:
- glucosamine sulfate
- glucosamine hydrochloride
- N-acetyl glucosamine
Some supplements combine glucosamine with other ingredients, such as chondroitin sulfate, shark cartilage, or methylsulfonylmethane, known as MSM.
Functions of glucosamine
The body uses glucosamine to build and repair cartilage. Cartilage is a flexible, tough, rubbery connective tissue that protects the bones in the joints. It provides padding and prevents the bones from rubbing together.
As people age, their cartilage can become less flexible and start to break down. This can lead to pain, inflammation, and tissue damage, which, for example, occurs in osteoarthritis.
There is some evidence that glucosamine might slow this process and benefit cartilage health.
Glucosamine occurs naturally in the body, but levels fall as people get older. In time, the reduction could contribute to joint deterioration.
Glucosamine Supplements
People take glucosamine sulfate supplements for many reasons, including:
- osteoarthritis
- glaucoma
- weight loss
- jaw pain
- joint pain
- back pain
- interstitial cystitis, a bladder condition
- multiple sclerosis (MS)
- HIV
- heart disease
- AIDS
Other uses of glucosamine
Some research in animals or human participants has indicated that specific forms of glucosamine may help:
- suppress changes that trigger irritable bowel disease
- dampen the immune response that leads to MS
- improve knee mobility after a sports injury
Side effects
Side effects of glucosamine appear to be mild and infrequent, but they can include:
- indigestion
- constipation
- diarrhea
- headaches
- rashes
The National Institutes of Health (NIH) note that oral glucosamine supplements are “likely safe” when taken correctly and by adults, but that some people have experienced mild side effects, including drowsiness, skin reactions, and headaches. They report that the injectable form is “possibly safe” when administered into muscle twice a week for up to 6 weeks.
Summarizing, oral glucosamine supplements appear to be relatively safe for adults without asthma, allergies, or diabetes, and for those who are not pregnant or breastfeeding.