Those four daily cups are enough to kick-start a protein called P27 that is found in the mitochondria—our cells' energy centres—that help protect the heart and repair damage to heart muscles after a heart attack.
This adds to the proven protective effects of coffee, which include lowering the risk for type 2 diabetes, heart disease and stroke.
The new study, by researchers at the Heinrich Heine University in Dusseldorf, Germany, discovered just how coffee has this protective effect. The missing link from earlier research is the discovery of mitochondria P27, which respond to high concentrations of caffeine, equivalent to four cups of coffee a day. The protein promotes endothelial cells, which line blood vessels and help protect the heart.
They also help repair damage caused by a heart attack (myocardial infarction), the researchers found.
Lead researcher Judith Haendeler says that coffee could be added to the diet of older people to help protect them from diabetes and heart disease. It's possible that promoting P27 proteins could even help people live longer.