Glucosamine and chondroitin are dietary supplements that may be useful in treating the pain of osteoarthritis. They are available both as individual supplements, as well as combined together. Although they share common characteristics, they also exhibit distinct differences; understanding these differences may help you decide whether to supplement with one, both or neither. However, as with any supplement, consult with your health-care provider for guidance before adding glucosamine or chondroitin to your diet.
Biochemistry
Both glucosamine and chondroitin function in building and maintaining the cartilage that surrounds and protects your joints. Glucosamine is a building block of a class of molecules called glycosaminoglycans -- long, unbranched chains of sugar molecules containing an amine, or nitrogen-containing group. Glucosamine functions as a precursor for several biological molecules and is a component of the glycosaminoglycan heparin. Chondroitin is a different type of glycosaminoglycan. It contains many negative charges, as do other glycosaminoglycans; both its charge and shape make it very viscous in solution. The viscosity of chondroitin allows for very little compression, rendering it ideal for lubricating and cushioning your joints.
Sources
Your body synthesizes both glucosamine and chondroitin, but the supplements arise from different sources. Glucosamine, not found in any foods, is plentiful in chitin, a substance that makes up the shells of crustaceans such as shrimp and crab. Most glucosamine supplements originate from this source, although laboratory-created glucosamine is commercially available as well. Chondroitin does not exist in food sources, either, but rather comes from animal cartilage, a by-product of the meat industry.
Mode of Action
Although it is unclear exactly how glucosamine and chondroitin may ease the symptoms of osteoarthritis, both supplements may help build new cartilage in your joints, increase the fluid surrounding your joints or prevent the breakdown of cartilage in the first place. The differences in how these supplements affect your joints are also unclear. MedlinePlus states that the sulfate available in some formulations of glucosamine may play an important part in creating new cartilage. According to New York University Langone Medical Center, chondroitin may impart an anti-inflammatory effect in your joints.
Safety
Glucosamine and chondroitin supplements have different safety profiles. Glucosamine supplements that originate from chitin may cause an adverse reaction if you have an allergy to shellfish. Glucosamine supplements may contain high levels of potassium or sodium, a potential contraindication if you are on a salt-restricted diet. Because both glucosamine and chondroitin share similarities with the heparin molecule, a natural anticoagulant, supplementing with glucosamine or chondroitin while taking a prescription blood-thinning medication, such as warfarin, may dangerously increase the anticoagulant activity of your medication. Other than that, chondroitin is considered to be a safe supplement.
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