Gwyneth Paltrow believes her family has been "cursed" by cancer.
The Oscar-winning actress lost her father Bruce to the disease in 2002, both her grandmothers and a cousin, who was only 23.
Gwyneth, 34, who is married to Coldplay frontman Chris Martin, is hoping her vegan diet will keep her healthy.
Speaking at an international anti-cancer campaign last night, she said: "I am challenging these evil genes by natural means. I am convinced that by eating biological foods it is possible to avoid tumors."
Gwyneth follows a macrobiotic diet, mainly consisting of whole grains, nuts, seeds, fruit and vegetables.
However, she does have a treat once in a while.
Gwyneth said: "I'm not as stringent as I was in the past. Now I'll have cheese once in a while or white flour, but I still believe in whole grains and no sugar."