14 DAY TRIAL // We all have heard from infancy that citrus fruits are the "fountain of health", a rich source of vitamin C and antioxidants. But, oops, American scientists have found that daily intake of grapefruit increases the risk of developing breast cancer by about 30 %!
Breast cancer is the most common form of female cancer, about 35 % of all cases, and previously alcohol drinking and overweight have been found as risk factors.
The research was made on 50,000 post-menopausal women and just by consuming a quarter of a grapefruit daily the risk raised by up to 30%. This citrus fruit is believed to increase levels of estrogen, the hormone behind this condition, but additional research is required to be 100% percent sure of these results.
The subjects filled questionnaires in which they stated how often they ate grapefruit and in which quantities.
The mixed team of the universities of South California and Hawaii discovered that women who ate at least one quarter of a grapefruit daily were much more exposed to breast cancer than those who did not consume the fruit at all were.
It was already known that the molecule named cytochrome P450 3A4 (CYP3A4) is connected to metabolizing estrogen hormones. Grapefruit could inhibit this compound, so that the hormones can accumulate. "It is well established that estrogen is associated with breast cancer risk. Therefore, if grapefruit intake affects estrogen metabolism leading to higher circulating levels, then it is biologically plausible that regular intake of grapefruit would increase a woman's risk of breast cancer.", wrote the researchers.
This is the first time when a commonly eaten food had been connected with a serious risk factor for breast cancer in older women.
Still, more research is required to confirm the investigation, which considered only the fruit's consume, but not grapefruit juice.
"This is an interesting study of a large group of post-menopausal women whose diet and health have been followed for many years. However, this study is simply a piece of the jigsaw that will eventually help us to understand how our diets affect our health. Although we are beginning to get a better awareness of how our diets can modify the risk of diseases such as cancer, we are still a long way from identifying particular foods that might specifically increase or decrease risk.", said Dr Joanne Lunn, a nutrition scientist at the British Nutrition Foundation.