Women who drink coffee regularly have a significantly lower risk of developing antiestrogen-resistant estrogen-receptor (ER)-negative breast cancer, researchers from the Karolinska Institute, Sweden, revealed in Breast Cancer Research.
Breast cancer may be sub-divided into hormone-responsive (estrogen receptor (ER) positive) and non-hormone-responsive subtypes (ER-negative).
The scientists compared the lifestyles of females with breast cancer and those without. They were matched for age. They also gathered data on their coffee consumption.
They discovered that regular coffee drinkers were less likely to develop breast cancer compared to women who either never or rarely drank coffee.
Other factors also impact on breast cancer risk, the authors added, such as the woman’s age when she reaches menopause, physical activity, her bodyweight, education, and family history of breast cancer.
After taking all these breast cancer risk factors into account, coffee only reduced the risk of developing ER-negative breast cancer.
The authors wrote:
“There is often conflicting information about the beneficial effects of coffee – when we compared our results to that of a German study we discovered that their data showed the same trend, but the relationship was much weaker.
We suggest that this may have something to do with the way the coffee was prepared, or the type of bean preferred. It is unlikely that the protective effect is due to phytoestrogens present in coffee since there was no reduction in the incidence of ER-positive cancer in this study.”
Even though it is clear coffee consumption does protect women from ER negative breast cancer, nobody is sure why this happens – we still do not know what the exact mechanisms are and what compounds are involved.
“Coffee consumption modifies risk of estrogen-receptor negative breast cancer” (PDF)
Jingmei Li, Petra Seibold, Jenny Chang-Claude, Dieter Flesch-Janys, Jianjun Liu, Kamila Czene, Keith Humphreys and Per Hall
Breast Cancer Research, May 2011
Written by Christian Nordqvist