Drinking three to five coffees a day may reduce the chance of premature death from a serious illness, scientists say. A new study conducted by experts at the Harvard TH Chan School of Public Health found that those who drink three to five cups of caffeinated or decaffeinated coffee a day, are less at risk of death from cardiovascular disease, neurological diseases, type 2 diabetes, and suicide than those who don't.

First author Ming Ding, a doctoral student in the Department of Nutrition, said: "Bioactive compounds in coffee reduce insulin resistance and systematic inflammation. That could explain some of our findings. However, more studies are needed to investigate the biological mechanisms producing these effects."

To reach their conclusion, the researchers analysed health data from more than 200,000 people – which included 74,890 women in the Nurses' Health Study; 93,054 women in the Nurses' Health Study 2; and 40,557 men in the Health Professionals Follow-up Study. Over a 30-year period, all participants were questioned every four years in food surveys which included questions on coffee consumption, according to the research paper published in Circulation. During the three decades, 19,524 women and 12,432 men passed away.

They found that moderate coffee consumption reduced the chances of developing and dying from cardiovascular disease, diabetes and neurological diseases such as Parkinson's disease. It was also noted that those who drunk three to five daily cups of coffee were less likely to commit suicide.

"This study provides further evidence that moderate consumption of coffee may confer health benefits in terms of reducing premature death due to several diseases," said senior author Frank Hu, professor of nutrition and epidemiology.