Previous research has produced a mixed and often confusing picture of the health effects of drinking coffee, quite often with conflicting results.
This latest study by researchers in Spain looked at people who drank caffeinated or decaffeinated coffee over more than 20 years.
The researchers led by Esther Lopez-Garcia of Universidad Autonoma de Madrid followed 84,214 U.S. women from 1980 to 2004 and 41,736 U.S. men from 1986 to 2004 and found that regular coffee drinking of up to six cups a day was not associated with increased deaths among the study's participants.
In fact, the middle-aged coffee drinkers, particularly the women, experienced a small decline in death rates from heart disease and no association was found between coffee consumption and cancer deaths.
Dr. Lopez-Garcia says the study indicates that coffee consumption does not have a detrimental effect and long-term coffee consumption may have some beneficial effects.
Coffee contains the stimulant caffeine and a number of other important compounds and some research has indicated that coffee is a good source of antioxidants that are thought to protect from heart disease, cancer and other diseases and also reduces inflammation in the body and improves the function in artery walls.
The study participants completed questionnaires every two to four years on how frequently they drank coffee, their diet habits, smoking and medical conditions and the researchers then studied the mortality risk over the period of the study among people with different coffee-drinking habits.
It was found that women who reported drinking two to three cups of caffeinated coffee per day had a 25 percent lower risk of death from heart disease than women who did not drink coffee and a smaller decreased risk was also seen for men.
The researchers say drinking decaffeinated coffee was associated with a small reduction in overall mortality risk.
At the start of the study none of the participants, who were health professionals such as nurses (female) taking part in the Nurses' Health study, and male doctors and dentists, had a history of cardiovascular disease or cancer.
The researchers say the strongest effect was in women and those who drank two to five cups of coffee a day were up to 26 per cent less likely to die from heart disease than abstainers and coffee consumption in women was also associated with a slightly lower risk of dying from chronic liver disease and cirrhosis.
The researchers say coffee drinkers can be reassured that coffee does not increase the risk of death.
The research is published in the journal Annals of Internal Medicine and was supported by the U.S. National Institute of Health - it involved researchers from Harvard School of Public Health, Brigham and Women's Hospital, Harvard Medical School and Universidad Autonoma de Madrid.