Do five coffees a day keep the doctor away?

A cup of coffee

We examine claims that drinking coffee can help your health.

According to new research, drinking coffee is associated with lower risk of death from cardiovascular disease (CVD), type 2 diabetes and neurological diseases such as Parkinson’s. Drinking coffee, researchers claim, may even lower the risk of suicide.

The study, published in the science journal Circulation, was led by researchers from Harvard School of Public Health and others. Lead researcher Ming Ding and colleagues analysed the health data of three large groups consisting of over 208,000 participants, male and female, aged between 25 and 75. The study groups were based on American nurses, dentists, pharmacists and other healthcare professionals, and those who already had cardiovascular disease or cancer were not included.

Their coffee intake was analysed every four years, by asking the men and women how many cups (caffeinated and decaffeinated) they consume on average a day, ranging from less than one cup to more than five cups.

Findings

In the whole population, coffee consumption (between three and five cups per day) was associated with lower risk of cardiovascular deaths and type two diabetes, but was associated with increased risk of lung cancer.

It is important to remember that maintaining a healthy lifestyle is what really matters, not how much coffee you drink

Senior Cardiac Nurse Emily Reeve

However, looking at those who have never smoked, coffee consumption was no longer associated with an increased risk of lung cancer. Non-smokers who drink more than five cups a day were found to have a reduced risk of CVD and type two diabetes compared to non-coffee drinkers, and a lower risk of neurological disease such as Parkinson’s, and even suicide.

Co-author Frank Hu said: “Regular consumption of coffee was found to be inversely associated with risk of mortality due to CVD. This study indicates that coffee can be incorporated into a healthy lifestyle.”

Strengths of the study include its large sample size, long follow-up (30 years), and efforts to adjust for other issues, such as smoking, which could affect the results. However, with all participants varying greatly in terms of health and lifestyle, other factors might have influenced the results. 

The study does not prove that coffee is the reason that coffee-drinkers were less likely to die. Another weakness was that size of coffee portions was only based on each participant’s estimation.

Apart from whether it was decaf, what type of coffee was drunk (eg freshly ground or instant) was not looked at, and nor was the milk or sugar added. Finally, it is important to note that the reduction in risk of death from drinking coffee, at less than 10 per cent relative risk, is small.

This study received widespread media coverage, including features in The Independent, Daily Telegraph, Daily Mail, Daily Express and Metro. However, some headlines were misleading. The Express headline said: “Drink coffee and avoid death,” which is rather overstating it. A healthy diet and lifestyle is much more important to a long and healthy life.

The BHF view

Our Senior Cardiac Nurse Emily Reeve said: “It is important to remember that maintaining a healthy lifestyle is what really matters if you want to keep your heart healthy, not how much coffee you drink.

“Previous research suggests that drinking up to five cups of coffee a day is not harmful to your cardiovascular health, and this study supports that. But more research is needed to fully understand how coffee affects our body and what it is in coffee that may affect a person’s risk of heart attack or stroke.”

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