Marc Hochberg from University of Maryland, School of Medicine and Daniel Clegg from the University of Utah, School of Medicine performed a post hoc analysis of the data from the second arm of the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT II) and found that people with milder forms of osteoarthritis may benefit the most from chondroitin sulphate supplementation.
Hochberg and Clegg report their findings in the journal Osteoarthritis and Cartilage.
Earlier this week researchers involved in GAIT II reported that supplements of chondroitin sulphate and glucosamine, alone or in combination, may not positively affect joint health.
Almost 400 patients with osteoarthritis of the knee participated in the 24-month, double-blind, placebo-controlled study, that is part of
Glucosamine is extracted from the shell of crabs, lobster and shrimps. Cargill also markets a non-animal, non-shellfish derived product. The ingredient is often used in combination with chondroitin sulphate, extracted from animal cartilage, such as sharks.
According to the Nutrition Business Journal, US sales for these combined supplements were $810 million (€563 million) in 2005.
Previous studies, including the $14m Glucosamine/chondroitin Arthritis Intervention Trial (GAIT), sponsored by the National Institute of Health, have reported positive results, while other have reported null results, leaving the subject clouded in uncertainty.
Post-study data analysis
Hochberg and Clegg looked at data from 1,583 people with an average age of 58.6 at the start of the study. Of these participants, 64 per cent were women, and 26.9 per cent of the study population suffered from swollen joints.
The statistical analysis showed that people with lower scores on the Kellgren/ Lawrence [K/L] scale, a well-established scale for osteoarthritis, were “substantially more responsive to the potential salutary effects of chondroitin sulphate than those with” higher scores, said the researchers.
Study fall-out
Following publication of results earlier this week, industry representatives in the US threw scorn on a study. The Washington-DC-based dietary supplements trade groups the Natural Products Association (NPA) and the Council for Responsible Nutrition (CRN) called the study’s findings irrelevant, as did a member of the study’s oversight committee.
“This study’s findings are useless and I am surprised it has been published at all,” said Jason Theodosakis, oversight committee member and assistant professor of medicine at the University of Arizona.
Daniel Fabricant, PhD, vice president, scientific and regulatory affairs at NPA criticized the study design and conclusions.
“Even the researchers seem to question their own findings,” he said. “If you look to the total body of research there is plenty of evidence that glucosamine and chondroitin do work for the estimated 20m Americans with osteoarthritis.”
Fabricant’s counterpart at CRN, Andrew Shao, PhD, called the results "perplexing and inconsistent" with the first GAIT results and other studies.
In the UK, about seven million people are reported to have long-term health problems associated with arthritis. Around 206m working days were lost in the UK in 1999-2000, equal to £18bn (€26bn) of lost productivity.
Osteoarthritis is estimated to affect 21 million people in the US.
Source: Osteoarthritis and CartilageOctober 2008, Volume 16, Supplement 3, Pages S22-S24“Potential effects of chondroitin sulfate on joint swelling: a GAIT report”Authors: M.C. Hochberg, D.O. Clegg