Glucosamine supplements may help you live longer, according to researchers from the University of Washington and the Fred Hutchinson Cancer Research Center in Seattle.

The first indication that glucosamine might prolong life came from a study involving over 77,700 people, aged 50 to 76, who were investigated for any link between the food supplements they were taking and total mortality over a five-year period. Unexpectedly, the researchers found that people who took glucosamine supplements on at least four days a week, for at least three years, were 17% less likely to meet their maker over the course of the study than those who’d never taken glucosamine. Similar results were found for chondroitin. This was strange, given that most people take glucosamine and chondroitin for their protective effects on joint pain due to osteoarthritis – not for any effects on diseases that can potentially shorten your life.

Glucosamine and life span

These protective effects of glucosamine in reducing mortality were so surprising that the researchers continued following 77,510 of the original participants for an average of eight years. Again, they found that people who took glucosamine, with or without chondroitin, had an 18% lower risk of dying, from any medical cause, at any age, compared with never-users. In particular, current use of glucosamine was associated with a significant 13% reduced risk of death from cancer and a 41% reduced risk of death from respiratory disease.

A more sensitive analysis was then performed, which removed the first two years of follow-up for each participant to exclude any pre-existing diseases. Rather than going down, this caused the protective effect of glucosamine to increase so that taking glucosamine supplements was associated with a 20% reduced risk of death from any cause.

What’s more, the protective effect remained even after accounting for other possible confounding factors such as smoking, weight, age, education, marital status, alcohol intake, physical activity, vegetable consumption, use of cholesterol-lowering medication (statins) or hormone replacement therapy.

How might glucosamine supplements improve longevity?

Glucosamine is helpful in treating joint pain as it inhibits production of the inflammatory chemicals associated with swelling, stiffness and discomfort. It’s possible that the reduction of inflammatory mediators in other body tissues may account for the lower incidence of cancer, lung and heart disease, too. This possibility was explored in a recent paper published in PloS One, a prestigious open-access journal.

In a small, randomized, double-blind, placebo-controlled trial, 18 healthy but overweight adults took either glucosamine hydrochloride (1500 mg per day) plus chondroitin sulfate (1200 mg per day) or placebo for 28 days. Overweight individuals were chosen because they generally have a higher level of inflammatory chemicals, making it easier to detect any small changes that might result from taking the supplements.

After a 28-day wash-out period, the volunteers then switched to take the other supplement (glucosamine plus chondroitin, or placebo) for a further 28 days. This allowed them to act as their own controls – any differences seen in levels of inflammatory markers were likely to result from the supplements rather than other confounding factors.

Blood levels of an array of inflammatory chemicals and protein markers were assessed, and the concentration of C-reactive protein (CRP – a major indicator of inflammation) was, on average, 23% lower in each individual after taking glucosamine and chondroitin than after they took placebo. Beneficial changes also occurred in the production of cytokines (signalling proteins involved in regulating the activity of inflammatory immune cells). Overall, the results showed that glucosamine and chondroitin may lower inflammation throughout the body as a potential mechanism for the observed association with a lower risk of lung and bowel cancer.

Other researchers have suggested another possible reason why taking glucosamine is associated with longevity. It appears to promote the breakdown of amino acids which cells can metabolise instead of carbohydrates. This may mimic the metabolic changes seen when following a low-carb diet, even when carbohydrates are eaten, to reduce insulin resistance and improve glucose control.

These are early days yet, but my guess is there are exciting times ahead for glucosamine. I stopped taking it when my creaky knees improved, but I’ve now stocked up again. The only question is – do I take one tablet, or two? Would a larger dose have a more pronounced effect on longevity? What dose do you take?

NB If you have diabetes, always monitor blood glucose levels when making any dietary changes or starting a new supplement. Reassuringly, a study from 2011 found that although glucosamine is made from glucose, taking glucosamine supplements had no effect on fasting blood glucose levels in individuals with diabetes, or those with impaired glucose tolerance.

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