October 20, 2000 – A notion that has been widely accepted since 1970, namely that dietary fiber protects against colon cancer, may need to be revised. A recent study even suggests that a psyllium supplement (Plantago ovata) can make things worse.
The team led by Dr Claire Bonithon-Kopp followed 665 patients with intestinal polyps, a form of pre-cancerous tissue, for 3 years. In animal models, dietary fiber shows strong anti-tumor activity. It was therefore believed that fiber supplementation could reduce the incidence of polyps and prevent them from turning into cancer. However, 29% of people taking a daily supplement of 3-5 g of psyllium developed at least one new polyp during the study period, compared to 20% in the group who took the placebo.
The researchers do not believe that these findings can be related, in general, to the role played by dietary fiber in bowel cancer, but believe that they confirm the results of two other recent studies, which have not. could demonstrate the protective function of dietary fibers in the prevention of colon cancer.
The theory of the protective function of dietary fiber dates back to the 1970s when the great differences in colorectal cancer between Western populations and those in Asia and Africa were highlighted where the rates are 5 to 15 per 100,000 people compared at 25-35 per 100,000 in the West. It was believed then that the amount of dietary fiber in the daily diet could explain this difference. The latest research suggests that the explanation will have to be found elsewhere.
However, this does not challenge the idea that the best diet is one that is low in fat and high in fiber from fruits, vegetables and whole grains.
Bonithon-Kopp C, Kronborg O, Giacosa A, Räth U, Faivre J Calcium and fiber supplementation in prevention of colorectal adenoma recurrence: a randomized intervention trial, Lancet, 2000; 356 (9238)
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