Australian scientists looked at the coffee consumption of almost 350 000 people aged 37 to 73 from the UK Biobank genetic database. They found “light” coffee drinkers - one or two cups a day - had the lowest risk of cardiovascular disease.
Compared with this group, the risk was 22% higher in people drinking more than six cups of coffee a day. This may be the point at which the risks of the beverage start to outweigh the benefits.
The findings may be explained by caffeine raising the blood pressure.
The study, published in the American Journal of Clinical Nutrition, is the first to place a limit on safe coffee consumption based on cardiovascular health.
The NHS says drinking more than four cups of coffee a day may increase blood pressure. But some experts believe caffeine may protect the heart as it contains natural antioxidants.