What Are Glucosamine and Chondroitin?
Glucosamine and chondroitin are structural components of cartilage, the tissue that cushions the joints. Both are produced naturally in the body. They are also available as dietary supplements. Researchers have studied the effects of these supplements, individually or in combination, on osteoarthritis, a common type of arthritis that destroys cartilage in the joints.
Cartilage is the connective tissue that cushions the ends of bones within the joints. In osteoarthritis, the surface layer of cartilage between the bones of a joint wears down. This allows the bones to rub together, which can cause pain and swelling and make it difficult to move the joint. The knees, hips, spine, and hands are the parts of the body most likely to be affected by osteoarthritis.
How much do we know about Glucosamine and Chondroitin Supplements?
- We have some information about the safety and usefulness of glucosamine and chondroitin from large, high-quality studies in people.
What do we Know About the Effectiveness of Glucosamine and Chondroitin Supplements?
- Research results suggest that chondroitin isn’t helpful for pain from osteoarthritis of the knee or hip.
- It’s unclear whether glucosamine helps with osteoarthritis knee pain or whether either supplement lessens osteoarthritis pain in other joints.
What do we Know About the Safety of Glucosamine and Chondroitin Supplements?
- Studies have found that glucosamine and chondroitin supplements may interact with the anticoagulant (blood-thinning) drug warfarin (Coumadin). Overall, studies have not shown any other serious side effects.
- If you take glucosamine or chondroitin supplements, tell your health care providers. They can do a better job caring for you if they know what dietary supplements you use.
Major studies of glucosamine for osteoarthritis of the knee have had conflicting results.
- A large National Institutes of Health (NIH) study, called the Glucosamine/chondroitin Arthritis Intervention Trial (GAIT), compared glucosamine hydrochloride, chondroitin, both supplements together, celecoxib (a prescription drug used to manage osteoarthritis pain), or a placebo (an inactive substance) in patients with knee osteoarthritis. Most participants in the study had mild knee pain.
- Those who received the prescription drug had better short-term pain relief (at 6 months) than those who received a placebo.
- Overall, those who received the supplements had no significant improvement in knee pain or function, although the investigators saw evidence of improvement in a small subgroup of patients with moderate-to-severe pain who took glucosamine and chondroitin together.
- For more information on the trial, see the NCCIH Web page.
- In several European studies, participants reported that their knees felt and functioned better after taking glucosamine. The study participants took a large, once-a-day dose of a preparation of glucosamine sulfate sold as a prescription drug in Europe.
- Researchers don’t know why the results of these large, well-done studies differ. It may be because of differences in the types of glucosamine used (glucosamine hydrochloride in the NIH study vs. glucosamine sulfate in the European studies), differences in the way they were administered (one large daily dose in the European studies vs. three smaller ones in the NIH study), other differences in the way the studies were done, or chance.
In general, research on chondroitin has not shown it to be helpful for pain from knee or hip osteoarthritis.
- More than 20 studies have looked at the effect of chondroitin on pain from knee or hip osteoarthritis. The quality of the studies varied and so did the results. However, the largest and best studies (including the NIH study discussed under the heading “Glucosamine” above) showed that chondroitin doesn’t lessen osteoarthritis pain.
A few studies have looked at whether glucosamine or chondroitin can have beneficial effects on joint structure. Some but not all studies found evidence that chondroitin might help, but the improvements may be too small to make a difference to patients. There is little evidence that glucosamine has beneficial effects on joint structure.
Experts disagree on whether glucosamine and chondroitin may help knee and hip osteoarthritis. The American College of Rheumatology (ACR) has recommended that people with knee or hip osteoarthritis not use glucosamine or chondroitin. But the recommendation was not a strong one, and the ACR acknowledged that it was controversial.
For Other Parts of the Body
Only a small amount of research has been done on glucosamine and chondroitin for osteoarthritis of joints other than the knee and hip. Because there have been only a few relatively small studies, no definite conclusions can be reached.
What the Science Says About Safety and Side Effects
- No serious side effects have been reported in large, well-conducted studies of people taking glucosamine, chondroitin, or both for up to 3 years.
- However, glucosamine or chondroitin may interact with the anticoagulant (blood-thinning) drug warfarin (Coumadin).
- A study in rats showed that long-term use of moderately large doses of glucosamine might damage the kidneys. Although results from animal studies don’t always apply to people, this study does raise concern.
- Glucosamine might affect the way your body handles sugar, especially if you have diabetes or other blood sugar problems, such as insulin resistance or impaired glucose tolerance.
- If your joints hurt, see your health care provider. It’s important to find out what’s causing your joint pain. Some diseases that cause joint pain—such as rheumatoid arthritis—may need immediate treatment.
- If you take warfarin or have blood sugar problems, make sure you talk to your doctor about potential side effects if you are considering or taking glucosamine or chondroitin supplements.
- If you’re pregnant or nursing a child, it’s especially important to see your health care provider before taking any medication or supplement, including glucosamine or chondroitin.
- Help your health care providers give you better coordinated and safe care by telling them about all the health approaches you use. Give them a full picture of what you do to manage your health.
This story originally published in the National Center for Complimentary and Integrated Health (NCCIH).