Do supplements protect against heart risk?
A study has found taking glucosamine, usually used for arthritis or joint pain, is linked to a lower risk of heart and circulatory disease. We look behind the headlines.
16 May 2019
People who regularly take glucosamine were found to have a lower risk of coronary heart disease, stroke and death from heart or circulatory diseases, according to a new study.
Scientists from Tulane University in New Orleans analysed information collected from 466,039 people taking part in the UK Biobank project, which is part-funded by the BHF.
Since it launched in 2006, UK Biobank has collected a wealth of information from participants about their lifestyles, genes and health outcomes. When participants joined the study, they were asked if they regularly take any supplements, and 19 per cent of people said they regularly take glucosamine.
Glucosamine supplements are taken by some people with joint pain (although it is not recommended by the health watchdog NICE to be prescribed for osteoarthritis, due to insufficient evidence that it works).
The researchers only studied people who did not already have heart or circulatory disease at the start of the study. After following the participants for an average of seven years, they found that those who took glucosamine were 18 per cent less likely to have developed coronary heart disease, nine per cent less likely to have had a stroke, and 22 per cent less likely to die from heart or circulatory disease.
Although the precise effects of glucosamine supplements in the body are unproven, it has been suggested that glucosamine could help to reduce inflammation. But more research is needed to understand whether glucosamine really causes these effects in humans, and if so why.
The results were published in the British Medical Journal.
How good was the research?
This was a large study involving nearly half a million UK participants, which means the results are less likely to be due to chance. However, it was an observational study rather than a controlled trial, in which people would be randomly allocated to take the supplement or a placebo, so that differences could be measured.
Observational studies like this can find associations but they can’t prove cause and effect. Rather than providing definitive answers, observational studies can highlight interesting questions for further research to address.
Observational studies like this can find associations but they can’t prove cause and effect.
It’s possible, for instance, that people who take dietary supplements, such as glucosamine, lead healthier lives overall, which could play a more significant role in their reduced risks of heart and circulatory disease.
The researchers did take into account people’s physical activity, diet, smoking habits and alcohol intake, but it’s possible that other lifestyle factors could be having an effect.
Another drawback of the study is that participants only answered the question about their glucosamine use once, and we don’t know how regularly they took the supplements or at what dose. Also, the study did not reveal whether other supplements taken by the participants showed similar associations, making it difficult to assess the significance of the glucosamine results.
The BHF view
Dr Sonya Babu-Narayan, Associate Medical Director at the BHF, said: “This study tells us about associations rather than cause and effect. We don’t know whether people who took glucosamine were less likely to develop cardiovascular disease because of the glucosamine itself, or if other factors were at play.
Controlled clinical trials will be needed to uncover whether glucosamine is beneficial in preventing heart and circulatory diseases
Dr Sonya Babu-Narayan, Associate Medical Director at the BHF
"For example, people who take glucosamine might be more likely to look after their health in general. Controlled clinical trials will be needed to uncover whether glucosamine is beneficial in preventing heart and circulatory diseases.
“If a well-known and widely available supplement like glucosamine could help prevent heart and circulatory diseases, including heart attack and stroke, it is an avenue of research worth exploring. Meanwhile, an important way to reduce your risk is to maintain a healthy lifestyle and when relevant take medications as recommended to you by your doctor.”
Glucosamine can also interact with the anticoagulant medicine warfarin so should be avoided if you are taking warfarin.
How the research was reported
The Sun headline misled readers by suggesting glucosamine was directly responsible for reducing health risks: “A 5p pill to ease joint pain cuts risk of fatal heart attack and stroke by a fifth, study says”. But the scientists only observed an association. Similarly, the Daily Mail claimed “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.”
The Mail did go on to point out drawbacks of the study, including that a ‘yes’ or ‘no’ answer from participants about their use of glucosamine supplements is insufficient to draw firm conclusions from.
The Mail also included this sensible advice from Professor Naveed Sattar from the University of Glasgow: “For now, I would not rush to buy glucosamine to lessen my heart risks when there are many other cost-effective proven ways to do so.”