Grapefruit may help keep heart and gum diseases at bay, but a new study has found that it can be dangerous for women, as it increases the risk of breast cancer by almost a third.
Researchers believe that this happens because eating the fruit can give the levels of oestrogen - the hormone associated with the risk of breast cancer - a boost.
The findings were based on a study carried out by researchers at the universities of Southern California and Hawaii, that included more than 50,000 post-menopausal women from five ethnic groups.
The group included 1,657 women who were suffering from breast cancer.
The researchers found that eating as little as a quarter of the fruit can increase the danger by 30 percent in women.
"This is the first report of a commonly consumed food that may increase the risk of breast cancer among post-menopausal women," the Daily Mail quoted the researchers, as saying.
"Whole grapefruit intake was significantly associated with breast cancer in the present study - generally a 30 per cent increase among women who consume the equivalent of one quarter of a grapefruit or more per day.
"There is evidence that grapefruit increases plasma oestrogen concentrations.
"Since it is well established that oestrogen is associated with breast cancer risk, it is plausible that regular intake of grapefruit would increase a woman's risk of breast cancer," they added.
The study and its findings are published in the British Journal of Cancer.