A new research revealed the three to five cups of coffee per day can actually decrease likelihood of premature deaths related to heart disease, Parkinson's disease, diabetes and even suicide. Whether it is caffeinated or decaf, scientists from the Harvard University Chon School of Public Health claimed its benefits.

In a large study of 200,000 women and 50,000 men, the team compared and grouped these individuals: those who do not drink, or drink less than two cups per day, and those who consume "moderately," or up to five cups per day. Initial results revealed no direct causal relationship and decreased risk of diseases.

However, when further study was done by assessing coffee drinking habits only to people who do not smoke, a clearer link was discovered. They found that those who consume a cup to three cups of coffee can lower their risk of dying to 6 to 8 percent compared with those who do not drink at all. While those who drink three and more than five cups have decreased death rate by 15 and 12 percent.

"This lower risk of mortality is consistent with our hypothesis that coffee consumption could be good for you [because] we have published papers showing that coffee consumption is associated with lower risk of type 2 diabetes and [heart] disease," said PhD student of Harvard University Public Health department of nutrition Ming Ding. "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," he added.

Aside from smoking, other contributing factors that need to be considered include body mass index, alcohol consumption, diet and exercise. Because of the study's limitation, that is, it is only based on a self-reported behavior obtained through surveys, experts caution that coffee may not be suitable for everybody. 

"Regular consumption of coffee can be included as part of a healthy, balanced diet," Frank Hu, professor of nutrition and epidemiology at Harvard, said. "However, certain populations such as pregnant women and children should be cautious about high caffeine intake from coffee and other beverages."

The study was published last Monday (Nov. 16) in the latest edition of the journal "Circulation."