In people glucosamine (C6H13NO5) is a precursor in the synthesis of glycosylated proteins, such as may be found in cartilage, and lipids. Glucosamine is also part of the structure of the polysaccharides chitosan and chitin, derived from the shells of shrimp, lobsters, crabs and other crustaceans. Glucosamine supplement (sulphate or hydrochloride complex) is produced commercially by the hydrolysis of shellfish exoskeletons or, less commonly, by fermentation of a grain such as corn or wheat.
The benefits of glucosamine supplementation are not clearly defined, although anti-inflammatory properties have been demonstrated. Indeed some studies have indicated benefits in preventing cancer, cardiovascular (CVD), and other diseases. Making use of the UK Biobank dataset, a study led by Chen Mao of Southern Medical University, Guangzhou, China, further evaluated the association between regular glucosamine supplementation and all-cause mortality, CVD, cancer, respiratory disease and digestive disease. The results were published in the journal Annals of the Rheumatic Diseases.
Approximately 20% of participants took glucosamine supplements. A significant inverse correlation between glucosamine supplementation and all-cause mortality was found. Interestingly the hazard ratios indicated that supplementation was most effective in reducing risk of death from respiratory and digestive diseases; risk was lower by 18% CVD, 6% cancer, 27% respiratory disease, 26% digestive disease. The protective effects were more pronounced in current smokers than non-smokers.
Importantly the authors analysis indicated that mortality risk reduction occurred equally well in the absence of chondroitin supplementation, which is often combined with glucosamine.
Limitations of the study include a lack of differentiation between the different glucosamine complexes available as supplements, which may have subtly different effects. It is possible an effect called ‘immortal time bias’ may have resulted in an overestimation of the protective effect, which must be considered. Glucosamine supplementation may simply be a proxy for people with a healthy lifestyle. Potential mechanisms involving reduced inflammation were speculated by the authors to be responsible for the observed reduction in mortality correlated with glucosamine supplementation, however these speculations remain to be confirmed.
“We observed that regular use of glucosamine supplements is associated with lower mortality due to all causes, CVD, cancer, respiratory disease and digestive disease. Further clinical trials and possibly pharmacological studies may increase our understanding of any potential benefit of glucosamine supplement use,” concluded the authors.