If you think they'll work ,they will. It's called placebo effect.

"In 2007, another well-designed study that involved 71 patients with osteoarthritis of the knee who were followed for one year. The study found no significant differences in function and pain between the treatment and placebo groups [5]. Later that year, a meta-analysis concluded: "Large-scale, methodologically sound trials indicate that the symptomatic benefit of chondroitin is minimal or nonexistent. Use of chondroitin in routine clinical practice should therefore be discouraged."

"Two studies reported in 2010 found that patients with chronic pain experienced no benefit from taking 1500 mg/day of glucosamine. One study involved 250 adults with chronic low-back pain and degenerative osteoarthtiris who were followed for one year. Half of the patients took glucosamine and half received a placebo. The glucosamine group did no better than the placebo group [8]. The other study involved 662 GAIT participants with moderate-to-severe knee osteoarthritis who received either glucosamine (500 mg three times daily), chondroitin sulfate (400 mg three times daily), glucosamine and chondroitin sulfate combined (same doses), celecoxib (Celebrex, 200 mg once daily), or a placebo. There were no statistically significant differences among the groups"

http://www.quackwatch.com/01Quackery...ucosamine.html