Glucosamine
Glucosamine is an amino sugar the body makes from glucose and glutamine to build cartilage and joint fluid. Food supplies almost none, so supplements are the source, usually sold for knee and hip osteoarthritis.
1,500 mga day, the amount most trials gave
1,583 people with knee osteoarthritis in the GAIT trial
Result · no better than placebo for pain overall
- In food Almost none shells and cartilage are not eaten
- Made from Shellfish shells or fermented corn
- Sold as Sulfate or HCl often with chondroitin
- Watch out Warfarin higher bleeding risk
Trial figures from the GAIT study (New England Journal of Medicine, 2006); safety from NCCIH. A studied amount, not a recommendation.
Glucosamine in Food and Supplements
Diet supplies little or no glucosamine. The parts of animals that hold it are the parts people throw away.
- Shrimp, crab and lobster shellsmade of chitin, a long chain of N-acetylglucosamine, from which glucosamine supplements are made
- Cartilage and connective tissuecontain glucosamine bound into larger molecules; how much survives cooking and digestion is not known
- Supplementsthe only real source: tablets and powders of glucosamine sulfate or hydrochloride, made from shells or by fermenting corn sugar
What Is Glucosamine?
Glucosamine is glucose with an amino group in place of one hydroxyl group. The body builds it from glucose and the amino acid glutamine, then links it into long chains called glycosaminoglycans. These chains, together with protein, form the cushioning part of cartilage and help make joint fluid slippery.
The idea behind the supplement is simple: give the body more raw material and it may repair worn cartilage. The body already makes all the glucosamine it needs, though, and there is no daily requirement for it. Two other joint supplements build on the same tissue: hyaluronic acid, itself one of these chains, and collagen, the protein that gives cartilage its strength.
What the GAIT Trial Found About Glucosamine
The Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), funded by the US National Institutes of Health, gave 1,583 people with knee osteoarthritis one of five treatments for 24 weeks: glucosamine hydrochloride 1,500 mg a day, chondroitin sulfate 1,200 mg, both together, the pain drug celecoxib, or a placebo.
Overall, neither supplement nor the combination eased pain significantly more than the placebo, while celecoxib did. In a small group with moderate to severe pain, the combination seemed to help, but the group was too small to be sure. A follow-up over 2 years found no slowing of joint damage on X-rays.
Why Glucosamine Studies Disagree
Several trials of glucosamine sulfate, many funded by one manufacturer, found a small benefit for pain. Independent trials and pooled reviews have mostly found little or none. NCCIH concludes that the research has not shown a clear benefit for osteoarthritis pain.
Who Should Be Careful With Glucosamine
- People taking warfaringlucosamine may strengthen its effect and cause bleeding
- People allergic to shellfishmany products come from shells; ask a doctor and check the source
- Pregnancy and breastfeedingsafety has not been studied
Glucosamine Supplement Forms
Supplements bind glucosamine to an acid, and sulfate products are usually stabilized with extra salt. All of that counts in the weight on the label.
| Form | Glucosamine in 100 mg | Glucosamine in 1,500 mg | Note |
|---|---|---|---|
| Glucosamine hydrochloride (HCl) | ~83mg | ~1,250mg | Used in the GAIT trial |
| Glucosamine sulfate, no added salt | ~79mg | ~1,180mg | Rarely sold this way, because it draws in moisture |
| Glucosamine sulfate with sodium chloride | ~63mg | ~940mg | Adds a little sodium; a stabilized sulfate of this kind was used in several European trials |
| Glucosamine sulfate with potassium chloride | ~59mg | ~890mg | Adds a little potassium |
So a 1,500 mg tablet of the potassium-stabilized sulfate holds about 360 mg less glucosamine than 1,500 mg of the hydrochloride. Chondroitin, often in the same tablet, is a separate ingredient with its own figure.
Sources: NCCIH, the GAIT trial reports. Ask a doctor or pharmacist before combining a supplement with a medicine.
Tracking Glucosamine in Caltide
- Not totaled yetCaltide does not add up glucosamine yet. Foods you log, including the shellfish in the food library, still count toward calories and nutrients.
Related Nutrients
Glucosamine Sources and References
The figures and claims on this page are checked against these sources.
Questions About Glucosamine
For most people, probably not much. The large NIH-funded GAIT trial found that glucosamine, alone or with chondroitin, did not relieve knee osteoarthritis pain better than a placebo overall, and later reviews reached similar conclusions.
Practically none that people eat. It is found in the shells of shrimp, crab and lobster and in animal cartilage, which is why supplements are made from shellfish shells or by fermenting corn.
It is not settled. Some trials of glucosamine sulfate, mostly from Europe, found a small benefit, while the GAIT trial used the hydrochloride and found none. The two salts also carry different amounts of glucosamine per gram.
Most trials, including GAIT, gave 1,500 mg a day, either at once or split into three doses of 500 mg. That is the studied amount, not a recommendation.
Ask a doctor first. Many products are made from shellfish shells, and labels do not always say the source. Some are made by fermentation and sold as shellfish-free.
Yes. NCCIH warns that glucosamine, with or without chondroitin, may increase the effect of the blood thinner warfarin and raise the risk of bleeding.
There is no good evidence that it does. In a 2-year part of the GAIT trial, glucosamine did not slow the loss of cartilage seen on X-rays any better than a placebo.
Track anywhere. On any device.
Your calorie counter and food diary in your pocket, free and without ads, with Tide one tap away.
- Log by photo, barcode or voice, right where you eat
- Steps and workouts from Apple Health and Health Connect
- The same log on your phone and in your browser, always in sync