Theres no conclusive evidence to guide a decision about glucosamine and chondroitin. The GAIT study did find that they are not harmful, and many people choose to try them. The dosages in the GAIT study were 1,500 mg a day of glucosamine and 1,200 mg a day of chondroitin. Dr. Husni tells her patients to try it for three months. If you dont notice a difference in symptoms such as pain or stiffness, dont waste your money, she says.