Feel guilty about that extra cup of coffee you swill down with your breakfast? Don’t.

A new study suggests that heavy coffee drinkers who gup between three and five cups a day could be cutting their risk of dangerous disease - and death.

Researchers from the Harvard T.H. Chan School of Public Health found that people who drank three to five cups per day (decaf or not) had a lower risk of cardiovascular disease, neurological diseases, type 2 diabetes, and suicide.

The study analysed data from large numbers of people over the course of about 30 years - based on food questionnaires about what people consumed, and tracked against death rate.

The researchers analysed data from three large, ongoing studies in America: 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.

‘Bioactive compounds in coffee reduce insulin resistance and systematic inflammation," said first author Ming Ding, a doctoral student in the Department of Nutrition.

‘That could explain some of our findings. However, more studies are needed to investigate the biological mechanisms producing these effects.