A large experiment suggests that trimming dietary fat and eating more fruits and vegetables may lower a woman's risk of dying of breast cancer.
It involved 49,000 women and spanned two decades, and is more reliable than many other studies that just observe how people eat and draw conclusions.
At the start, women were getting one third of daily calories from fat. One group lowered that to 24% after one year and to about 30% after eight years.
Two decades later, those who trimmed fat intake had a 21% lower risk of dying of breast cancer. The diet change did not affect the risk of developing the disease though.
Results were reported Wednesday in a telephone news conference held by the American Society of Clinical Oncology.