U.S. researchers found more than 28 cups of coffee a week increases by half the chances of premature death in younger people.Drinking four cups of coffee a day could put you at higher risk of dying young, warn researchers.They found more than 28 cups of coffee a week increases by half the chances of premature death in younger people.But there was no change in risk for coffee drinkers aged over 55.The findings come from a large scale American lifestyle study of 43,727 individuals aged 20 to 87.The U.S. 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.However, the latest study conflicts with a number of others showing moderate coffee drinking is linked with longevity.During the study around 2,500 deaths were recorded, just under a third of which were due to heart and artery disease, over an average 16-year period.Participants who consumed higher amounts of coffee were also more likely to smoke, and had less healthy hearts and lungs.The risk of death from all causes rose by 56 per cent for both men and women younger than 55 years of age who drank more than 28 cups of coffee a week, the equivalent of four a day. Younger women who consumed more than four cups a day had more than double the risk of dying from any cause compared with those who did not drink coffee, said a report in the journal Mayo Clinic Proceedings.Researcher Steven Blair of the Arnold School of Public health, 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.’