A cheap dietary pill used to soothe the agony of arthritis can slash the risk of a heart attack or stroke by more than a fifth, according to research.
A study of almost half a million people found those who used glucosamine regularly were up to 22 per cent less likely to die from cardiovascular disease (CVD).
Researchers believe the supplement slashes levels of C-reactive protein (CRP) - a chemical associated with inflammation and heart attacks.
But critics doubt the findings, saying the dose of glucosamine consumed was not specified and it wasn't clear if participants were taking other supplements.
Glucosamine is a supplement consumed by millions of people around the world to ease the misery of joint pain.
Glucosamine use slashed the risk of cardiovascular disease by more than a fifth in a study of almost 500,000 Brits
Animal studies have found that it can both delay the breakdown of and repair damaged cartilage.
The compound is produced naturally by the body in cartilage between the joints.
But evidence on whether it works in humans is mixed, with many studies showing little or no effect on pain relief or joint function.
Researchers from Tulane University in New Orleans, Louisiana, followed 466,039 male and female Britons without CVD for an average of seven years.
Using death certificates and hospital records they found glucosamine was associated with a 15 per cent lower risk of CVD events.
The findings also showed that coronary heart disease (CHD), strokes and deaths from CVD were reduced by between nine and 22 per cent.
These associations remained after taking account of traditional risk factors, including age, sex, weight (BMI), ethnicity, lifestyle, diet, medication and other supplement use.
Overall, almost one in five participants - 19.3 per cent - reported glucosamine use at the start of the study.
Lead researcher Professor Lu Qi said: 'Several potential mechanisms could explain the observed protective relation between glucosamine use and CVD diseases.
Regular use of glucosamine was associated with a statistically significant reduction in CRP concentrations, which is a marker for systemic inflammation.
'Animal studies also reported that the anti-inflammatory properties of glucosamine might have a preventive role in the pathophysiology of CVD.
'In addition, a previous study found that glucosamine could mimic a low carbohydrate diet by decreasing glycolysis and increasing amino acid catabolism in mice; therefore, glucosamine has been treated as an energy restriction mimetic agent.
'Other mechanisms might also be involved, and future investigations are needed to explore the functional roles of glucosamine in cardiovascular health.'
The new findings, published in The British Medical Journal, are based on an analysis of data from the UK Biobank study that contain the health records of hundreds of thousands of
