Grapefruit and grapefruit juice seem to be causing problems

It seems that consumption of just a quarter of a grapefruit per day increases a woman's risk of breast cancer by 30%.

http://news.bbc.co.uk/2/hi/health/6900482.stm

Grapefruit also seems to interfere with many drugs.

https://secure.pharmacytimes.com/lessons/200303-02.asp

Oranges and orange juice and other citrus fruits do not seem to cause these problems.