The first indication that glucosamine has long-term health benefits came in 2010, when researchers from the University of Washington and the Fred Hutchinson Cancer Research Center, investigated whether any popular food supplements could affect mortality. Out of 77,719 people, aged 50 to 76, those who took glucosamine on at least four days a week, for at least three years, were 17% less likely to die from any medical cause over the following five years than those not taking glucosamine. Similar results were found for chondroitin.
Surprised by these results, the researchers continued following 77,510 of the original group for an average of eight years. Again, they found that use of glucosamine (with or without chondroitin) was associated with an 18% lower risk of mortality compared with non-users. When a more sensitive analysis was performed, which removed the first two years of follow-up for each participant to help exclude any pre-existing diseases, the protective effect of glucosamine increased to a 20% reduced risk of death from any cause. What’s more, the protection remained even after accounting for other confounding factors such as smoking, weight, age, education, marital status, alcohol intake, physical activity, vegetable intake, cholesterol-lowering medication and HRT.
Protection against heart disease
Then a study in Australia, published in 2012 and involving 266,844 people, found that taking glucosamine was associated with a 21% lower risk of heart attack or angina, and an 18% lower risk of other heart diseases than non-users.
The latest evidence, published in the BMJ in 2019, looked at a UK database of 466,039 people who did not initially have heart disease. Over the following 7 years, those taking glucosamine were consistently less likely to develop both fatal and non-fatal coronary heart disease than those not taking it. Habitual glucosamine use was associated with an 18% lower risk of coronary heart disease, an 18% lower risk of developing a stroke, and a 22% lower risk of cardiovascular death. These associations were independent of other more traditional risk factors such as sex, age, income, body mass index, level of physical activity, healthy diet, alcohol intake, smoking status or whether they had diabetes, hypertension, high cholesterol, arthritis or took any other drugs or supplements such as fish oil. In fact, for smokers, the protective benefits were increased. Habitual glucosamine use was associated with a 12% lower risk of coronary heart disease in never smokers, an 18% lower risk in former smokers and a 37% lower risk in current smokers compared with those who did not take glucosamine.
How does it work?
Glucosamine is known to reduce inflammation and to lower levels of C reactive protein, for example, which is a marker for widespread inflammation. This effect not only reduces the joint pain associated with arthritis but may also protect against heart disease. As smoking increases levels of inflammation in the body, this may also account for the increased protection seen in smokers.
Another possibility is that glucosamine acts as a signal to change cell metabolism in a beneficial way. Preclinical studies suggest that glucosamine promotes the breakdown of amino acids for cells to use as a fuel instead of glucose. This may reflect the metabolic state of an energy restricted diet. Quite why this protects against heart disease is poorly understood, but energy restriction is the only nutritional intervention shown to delay ageing in humans.
These are exciting times for glucosamine research, and I for one am glad I started taking it for dodgy knees several years ago!
Pocobelli G et al. (2010). Total mortality risk in relation to use of less-common dietary supplements, Am J Clin Nutr
Bell GA et al. (2012). Use of glucosamine and chondroitin in relation to mortality, Eur J Epidemiol
Sibbritt D et al. (2012). Who uses glucosamine and why? A study of 266,848 Australians aged 45 years and older, PLoS One
Simon RR et al. (2011). A comprehensive review of oral glucosamine use and effects on glucose metabolism in normal and diabetic individuals, Diabetes Metab Res Rev
Ma H et al. (2019). Association of habitual glucosamine use with risk of cardiovascular disease: prospective study in UK Biobank, BMJ
Weimer S et al. (2014). D-Glucosamine supplementation extends life span of nematodes and of ageing mice, Nature Communications
Nikolai S et al. (2015). Energy restriction and potential energy restriction mimetics, Nutr Res Rev