New research suggests that drinking coffee or eating caffeine-laden foods doesn’t increase overall breast cancer risk.

Caffeine, the world's most widely consumed drug, is found in beans, leaves and fruits of more than 60 plants, where it works as a natural pesticide by paralyzing and killing some insects feeding upon the plants. In humans, caffeine, whose sources include coffee, soft drinks and energy drinks, as well as tea, stimulates the central nervous system and has many negative effects. However, it doesn’t seem to be connected to breast cancer risk, according to a new report.

Caffeine "does not appear to be associated with overall risk of breast cancer," said study co-author Dr. Shumin M. Zhang, M.D., assistant professor of medicine, Harvard Medical School and assistant professor of epidemiology, Harvard School of Public Health.

Nonetheless, the study’s authors noticed a significant link between women drinking every day four cups of coffee or more, and an increased risk for benign breast disease. In addition to this, researchers also found that caffeine may speed the evolution of aggressive forms of breast cancer.

39,310 women participated in the study, which was funded by the National Institutes of Health. All women, who worked as health-care professionals, were aged 45 or more and were followed over a period of four years, between 1992 and 1995. The findings appeared in the Oct. 13 number of the Archives of Internal Medicine.