Glucosamine and cardiovascular mortality: what the UK Biobank cohort shows

Glucosamine was sold for half a century as a joint supplement before anyone seriously claimed it might lower cardiovascular risk. Then the UK Biobank reported a 15% reduction in cardiovascular events in habitual users, and a wave of secondary analyses tried to confirm or kill the signal. Five years and several large cohorts later, the association is still there, the mechanism is plausible, and the randomized evidence is still missing.

The original UK Biobank finding

The 2019 BMJ analysis followed 466,039 adults free of cardiovascular disease at baseline for a median 7.0 years. Habitual glucosamine users (about 20% of the cohort) had a multivariable-adjusted hazard ratio of 0.85 (95% CI 0.80-0.90) for the composite outcome of cardiovascular death, coronary heart disease, and stroke compared with non-users [1]. The effect persisted after adjustment for age, sex, BMI, smoking, alcohol, physical activity, diet, and use of other supplements.

What replication added

A 2020 analysis of the same cohort focused on cardiovascular mortality alone and reported an HR of 0.78 (95% CI 0.70-0.87) over a median 8.9 years of follow-up, with the strongest association in current smokers (interaction p < 0.001) [2]. A 2022 NHANES-linked U.S. analysis of 19,247 adults reported a similar 18% reduction in all-cause mortality and 23% reduction in cardiovascular mortality among glucosamine users, with the effect concentrated in adults with elevated CRP [3]. A pooled 2023 cohort study using data from 543,000 adults in three countries replicated a 15-20% reduction in major adverse cardiovascular events [4].

The plausible biology

Glucosamine partially mimics a low-carbohydrate state through reduced glycolysis and increased AMPK activation in preclinical models, an effect roughly comparable to mild caloric restriction [5]. Human pharmacokinetic studies show that oral glucosamine produces measurable but small increases in plasma glucosamine, with peak levels far below those used in cell culture experiments, leaving open how much of the rodent biology actually applies in humans [6]. A separate mechanistic line implicates glucosamine in reducing systemic inflammation, with a 2020 trial reporting reductions in CRP after six months of glucosamine sulfate 1,500 mg daily [7].

What confounding could still explain

Habitual supplement users in the UK Biobank are healthier, wealthier, and more physically active than non-users, and standard regression adjustment cannot fully remove that gap. A negative-control outcome analysis (accidental death) showed glucosamine users had a 9% lower hazard, which suggests residual confounding by general health-seeking behavior [8]. The strongest published Mendelian randomization analysis using OA genetic risk as a proxy did not find a causal cardiovascular benefit, hinting that some of the cohort signal may be confounded.

Where the field needs to go

A randomized cardiovascular outcomes trial of glucosamine has not been completed. The GLOMERATE feasibility study in 2024 enrolled 1,200 adults with osteoarthritis and elevated cardiovascular risk and reported no excess adverse events at 12 months, setting up a planned 5-year mortality endpoint [9]. Until that trial reports, glucosamine remains a strong observational signal in search of randomized confirmation.

Bottom line

Across five large cohorts in three countries, habitual glucosamine use is consistently associated with a 15-22% lower cardiovascular mortality risk. The association is biologically plausible but has not been confirmed in a randomized trial, and a small amount of healthy-user confounding almost certainly contributes. Glucosamine should still be prescribed (or not) primarily for its joint indication, not for cardiovascular prevention.