The risk assessment provides companies with a guide for safe upper levels for product formulations, and consumers with vital information on safe dosage levels from products.
Glucosamine is extracted from the shell of crabs, lobster and shrimps, and also marketed by Cargill in a non-animal, non-shelfish derived product. Chondroitin sulfate is extracted from animal cartilage like shark cartilage.
They are the most commonly used supplements for osteoarthritis, with estimated sales of $730m in the US in 2004.
"Glucosamine and chondroitin sulfate are two dietary ingredients whose use continues to increase among Americans… The present review provide[s] for a high level of confidence in the safety of these ingredients," said the authors of the study, John Hathcock, PhD and Andrew Shao, PhD.
The authors applied a safety evaluation method as described in the CRN's Vitamin and Mineral Safety, 2nd Edition which contains the basic features of the US Food and Nutrition Board's risk assessment method, as well as the observed safe limit (OSL) modification adopted as a highest observed intake (HOI) in the FAO/WHO 2006 report.
The absence of any critical effects prevented the expression of the limits as no observed adverse effect levels (NOAEL). Values were presented as OSLs.
None of the clinical trials with glucosamine reported any adverse effects. This is important since there have been some concerns about glucosamine affecting glucose control or diabetes.
One clinical trial using a dose of 2000 milligrams per day of glucosamine hydrochloride for 12 weeks did not result in any more adverse reactions than placebo. This data was supported by other clinical trials using smaller doses, and animal and in vitro studies extrapolated to amounts observable in humans.
"Identification of 2000 mg per day as the OSL for oral consumption of glucosamine (either the hydrochloride or the sulfate) carries little uncertainty, due to the confidence gained from substantial safety in animal and in vitro tests," concluded Hathcock and Shao.
They did note however that allergic warnings are appropriate and required for glucosamine of shell fish origin.
Similarly, for chondroitin sulfate, no adverse effects were observed for any of the doses used in clinical trials, and because there was sufficient human data, no animal data was required in the determination of the OSL for the ingredient.
"The highest chondroitin sulfate dosage that has been utilized in clinical trials is 1200 mg per day," wrote Hathcock and Shao. "There are sufficient data at this level to identify it as the OSL."
The Council for Responsible Nutrition's (CRN) John Hathcock and Andrew Shao have been busy filling in the gaps for a range of micronutrients, and the new assessment, published on-line in the journal Regulatory Toxicology and Pharmacology (doi: 10.1016/j.yrtph.2006.07.004), follows Co-Q10, creatine, carnitine, and lutein and lycopene in the same journal.