Women now have one less reason to feel guilty about taking that extra shot of espresso: a recent study by researchers at Harvard Medical School has revealed no significant relationship between caffeine consumption and overall risk of developing breast cancer.

The study, which was led by Shumin Zhang, an assistant professor at the Medical School, contradicts earlier studies that suggested that massive caffeine consumption could increase the risk of benign breast disease.

Some previous studies even said that caffeine could accelerate the development of aggressive forms of breast cancer.

For his research, Zhang and fellow scientists monitored women who drank four or more cups of coffee each day for more than 10 years in order to evaluate the association between the female consumption of caffeine—the world’s most commonly ingested drug—and breast cancer.

The researchers determined that the consumption of caffeinated beverages and food—such as coffee, soda, and chocolate—was not significantly associated with an overall increased risk of malignant growth. The collected data showed that the women who drank more than four cups a day exhibited the same risk of developing breast cancer as those with less affection for a cup of joe.

Zhang said that women who consume caffeine need not be worried, as his research so far has been consistent with this finding.

But it is possible that consuming four or more cups of coffee per day may increase breast cancer risk in those with a history of benign breast disease.

“Overall, the results of this study should be reassuring to women who are concerned about their risk of breast cancer and who also like to drink coffee moderately,” Zhang said.

The study should be especially good news for undergrads, who consume an enormous amount of coffee in residential dining halls every year—approximately 10,700 pounds, according to Harvard University Dining Services spokeswoman Crista Martin.

“This is great news for me, and I’d imagine for many women at Harvard,” said Justine R. Lescroart ’09. “I feel like if the study’s results had gone the other way, there would be widespread panic. Everyone likes coffee, and no one wants breast cancer.”

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