Researchers at the University of Leeds, Great Britain, argue that dietary fiber, particularly from cereal and whole grains, play a role in preventing breast cancer in women aged 50 and under.

Dietary fiber has different functions in our body; it would benefit overweight people as it gives the sense of satiety, and in turn lower their food intakes.

But that has been hard to prove. Studies of dietary fiber and colon cancer failed to find that fiber was protective, and studies of vitamins thought to protect against cancer failed to show an effect.