A UK observational study purporting to show that glucosamine may reduce cardiovascular disease has been met with scepticism by Australian experts.

Published in the BMJ, the analysis of data from 466,039 people without cardiovascular disease found a 15% lower risk of cardiovascular events  during seven years of follow up among those who reported using glucosamine at baseline.

Almost one in five (19.3%) participants reported glucosamine use at the start of the study, among whom there was a 15% lower risk of total cardiovascular events, and a 9-22% lower risk of coronary heart disease (CHD), stroke and cardiovascular death compared with no use.

The association between glucosamine use and CHD was also stronger in current smokers (37% lower risk) compared with never (12%) and former smokers (18%).

The study authors said the mechanism of glucosamine’s apparent effect on cardiovascular disease might be related to reduction in levels of C-reactive protein (CRP), a well known marker for inflammation.

They noted that glucosamine supplements are widely used to treat osteoarthritis and joint pain despite its effectiveness being debatable. Its association with lower rates of cardiovascular disease might be a marker of a more health conscious lifestyle, they said.

Dr Louisa Lam, Deputy Dean of the School of Nursing and Healthcare Professions at Federation University Australia, Victoria, said the findings could have arisen by chance because the study lacked basic measures such as length of exposure to glucosamine.

“I do have my doubts about this analysis … the study has a very large sample, and with large samples like that, it is easy to find some statistical significance in ‘things’ the researchers want,” she said.

“I would really like to see if there is an association with other supplements and cardiovascular events or death. The authors should provide information on other supplements as comparisons. Also, a Yes and No answer on the use of glucosamine is insufficient. We need dose and length information.”

Dr Peter Clifton, Professor of Nutrition at the University of South Australia with an interest in cardiovascular disease, said there was biological plausibility for a glucosamine benefit, but little convincing evidence.

“It is likely the observation of reduced CVD risk in glucosamine consumers is due to unmeasured confounders as the glucosamine group was a healthier  group and even exercised more  … and a more affluent group,” he said.

“Time for a secondary CVD prevention study with glucosamine,” he suggested.