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I have always wondered about the effect of caffeine on breast cancer. Does caffeine encourage breast cancer or increase the risk of breast cancer or any other cancer because it speeds up the body's metabolism? I use decaffeinated coffee (about 1/2 teaspoon of decaffeinated coffee crystals daily). Am I putting myself at risk?
The good news is that we have research from large studies to show that there's no increase in risk of breast cancer for women who drink coffee.
The largest study was of over 38,000 women and did not reveal an increased risk in breast cancer (Arch Intern Med 208; 168(18):2022-2031). The research did reveal that for those women with benign breast disease (fibrocystic disease and the like) there might be an increased risk of certain types of breast cancer. This was not statistically significant, however, and was only for those drinking over 4 cups of coffee per day.
In another study researchers looked at both caffeinated and decaffeinated coffee. That research had about 86,000 participants followed over 22 years and there was no difference in breast cancer risk for those drinking either coffee (caffeinated or decaffeinated). They actually showed a weak relationship with those post-menopausal women drinking the most coffee: they had a slightly lower risk of developing breast cancer.
So, the research says that you're good to go whether your coffee is high-test or unleaded.
Thanks for writing,
Timothy S. Harlan, MD, FACP, CCMS