A federal study has found that two of the most popular nutritional supplements which soothe arthritis pains are not effective, namely glucosamine and chondroitin sulfate.

The studies took 24 weeks and were conducted on 1 583 patients with arthritis of the knees; some took one drug, some took the other, others took both or placebo.

The first two groups, which took the two drugs separately, experienced no relief; those who took them together experienced a moderate relief of the pains. The tests included also Celebrex, a drug for osteoarthritis, which showed rather good results.

Daniel Clegg, doctor at the University of Utah School of Medicine and conductor of the research, stated: "The bottom line is, over all there wasn't any benefit over placebo."

Studies at 16 different centers show the same results as the one mentioned here. The present one is aimed to clarify some still uncertain effects of drugs; "there is a real and urgent public health need to test these agents in a rigorous way," Clegg said.

Some researchers see these studies as inconclusive, because they can be evidence of a fluctuation of data, questioning their rigor.

Almost one in three Americans experience some form of arthritis throughout their lifetime, raising treatment costs to nearly $86 billion dollars, among which $734 million alone were spent on these two drugs, making them one of the most popular in the country.