Obviously, there is no reason to banish this nutrient rich fruit as of yet, the problem may be in eating it too often.  It seems that those who eat just a quarter of a grapefruit ever day could raise their risk of developing breast cancer by almost one third. 

The study, as reported in the British Journal of Cancer, looked at 50,000 post-menopausal women.  The researchers, out of Southern California and Hawaii universities, speculate that the fruit may boost levels of oestrogen, a hormone associated with a higher risk of breast cancer.

This is not the first time grapefruit has received a finger pointing.  Grapefruit juice is often warned against when taking certain medications, as it may inhibit drug uptake in the intestine.  Of course, this breast cancer - grapefruit research is very preliminary and still quite speculative, but it is interesting nonetheless.