London - Drinking four cups a day could raise your risk of dying young, researchers warn – but only if you’re under 55.
They found that consuming 28 cups of coffee a week increases the chances of premature death in younger people by half.
The findings come from a large- scale American lifestyle study of 43 727 individuals aged 20 to 87.
The US researchers suspect excessive coffee consumption may adversely affect the body’s metabolism, outweighing some of the known health benefits.
Individuals with a “genetic coffee addiction” may be prone to these harmful effects, they suggest.
But the latest study conflicts with a number of others, which have linked moderate coffee consumption with longevity.
Around 2 500 deaths were recorded over the course of the 16-year study. Just under a third of these were because of heart and artery disease.
Participants who drank more coffee were also more likely to smoke, and had less healthy hearts and lungs.
The risk of death from all causes rose by 56 percent for men and women younger than 55 who drank more than 28 cups of coffee a week, said a report in the journal Mayo Clinic Proceedings.
Researcher Steven Blair, of the University of South Carolina, said: “Significantly the results did not demonstrate any association between coffee consumption and all-cause mortality in older men and women.”
But the researchers did not explain why coffee did not affect older people in the same way. Coffee contains thousands of different chemicals, which can have both good and bad effects on health.
Recent research has shown that coffee is a major dietary source of antioxidant, and it may reduce inflammation and boost brain function.
At the same time, coffee stimulates the release of adrenalin, inhibits insulin activity, increases blood pressure, and raises levels of homocysteine, a harmful chemical linked to heart disease and dementia.
Co-author Dr Carl Lavie, from Ochsner Medical Center in New Orleans, said: “There continues to be considerable debate about the health effects of caffeine, and coffee specifically, with some reports suggesting toxicity and some even suggesting beneficial effects.”
Dr Euan Paul, executive director of the British Coffee Association, said the study’s limitations may have skewed the findings.
The use of a questionnaire can result in recall bias, with people struggling to remember how many cups of coffee they have consumed in the past week, he said.
Other factors such as smoking and poor fitness could partly explain the link with premature death.
Previous studies have found either no link between coffee consumption and heart deaths, or a positive effect, he added.
He said: “There is a growing body of data which suggests that coffee is perfectly safe when consumed in moderation – four to five cups a day – and as part of a balanced diet.” - Daily Mail