British health researchers say post-menopausal women may increase their risk of breast cancer by consuming an otherwise healthy food grapefruit.
The study says the citrus fruit boosts levels of oestrogen and can increase the risk of breast cancer by almost one third.
The research was published in the latest issue of the British Journal of Cancer. It says that eating as little as a quarter of a grapefruit each day can increase the breast cancer risk by as much as 30 percent.
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, the study warned.
The researchers focused on evidence they said indicated that grapefruit increases concentrations of estrogen, a hormone associated with breast cancer. Since oestrogen is linked to cancer risk, they concluded, grapefruit must be considered a contributor to the risk factor.
The study was carried out by the universities of Southern California and Hawaii. The study group was made up of more than 50,000 post-menopausal women from various races, including more than 1,600 with breast cancer.
