A massive study of European eating habits and U.S. research into diet and early signs of bowel or colorectal cancer show consuming foods rich in fiber cuts the risk of developing the disease, which affects more than 940,000 people in the world each year.
In the European study, which the researchers called the largest ever on the relationship between diet and cancer, the scientists tracked more than a half million people in 10 countries for an average of 4 1/2 years.
“People in the top 20 per cent who had the biggest reduction were eating far more fibre than in other studies which have not shown a relationship,” said Professor Sheila Bingham, who conducted the European study.
Those who averaged 35 grams of daily fibre intake had a 25 percent lower risk of colorectal cancer, primarily colon cancer, compared with those who averaged 15 grams of fibre a day, the study found. The correlation proved strongest for colon cancer and was not statistically relevant for rectal cancer, the study says.
“Eat more plant foods because then you’re eating more whole-grain cereal, more fruits and vegetables – that’s the message coming through,” adds Bingham, head of the diet and cancer group at the UK Medical Research Council’s Dunn Human Nutrition Unit in Cambridge.
To achieve those protective effects, the latest research suggests, Americans would have to consume much more fiber than they currently do. The U.S. study says Americans average about 16 grams of fiber a day.
“In our study, high intakes of dietary fiber, especially from grains, cereals and fruits, was associated with lower risk of colon adenoma,” Ulrike Peters, of the National Cancer Institute, said in the study.
Cancers of the bowel and rectum are rare in developing countries but kill more than 490,000 people in industrialized states each year, according to the International Agency for Research on Cancer in Lyon, France.
The European study showed different sources of fiber among people in the 10 countries, but the researchers said it did not seem to matter where it came from. People with the lowest risk were eating five or more portions of fruit and vegetables a day plus the equivalent of five slices of whole-meal bread.
“The more the better is the answer,” Bingham said.