How dietary fiber protect us against colon cancer?

According to the studies, dietary fiber can reduce the risk of colon cancer. But most of the data comes only from dietary questionnaires and therefore are inaccurate. That fiber can actually reduce the likelihood of colorectal cancer, now a study has confirmed that fact.

Colorectal cancer is one of the most common cancers in the Western industrialized nations. Colorectal cancer consist of more than 95 percent of malignant colon tumors. As prophylaxis is often recommended intake of fiber, which was confirmed by several studies. However, some studies also point to the absence of benefits from dietary fiber.

A major shortcoming of these studies has been that most of the data were determined from nutritional questionnaires. Diet questionnaires reflect information very inaccurately, no longer leaving no exact information on how many fibers have really taken the participants of study. Now, scientists have succeeded to review the protective effect of dietary fiber against colon cancer based on a biomarker.

Biomarkers of dietary fiber.

The researchers have examined the samples of blood of nearly 2750 participants in a major European population study (“EPIC”) for biomarkers. 50 percent of the subjects were diagnosed with colon cancer during the study. All samples were taken prior to the cancer diagnosis. The American scientists examined the blood samples on so-called Alkylresorcinols – phenolic compounds, which are particularly frequent met in the shells of cereals and can be readily detected in the serum. Intervention studies have shown that the normal values of these phenols are strongly influenced by the consumption of whole grains. Wholemeal turns in one of the major suppliers of fiber.

Dietary fiber reduce risk of distal colorectal carcinoma.

It turned out that subjects with high serum levels in fiber had a significantly lower risk of developing colon cancer than participants with low scores. However, this applies only for tumors in the distal colon, but not in others; Here whole grains seem to have no effect. In the distal colon – when comparing the quartiles with the highest and the lowest serum levels – even reduce the likelihood of developing colon cancer by half.

Why only the distal colon seem to benefit from a high fiber consumption, the study authors could not explain exactlya. Scientists suspect that histological differences between the colon segments can be a cause. But also the longer residence time and higher concentration of the stool in the distal colon could be a reason. The protective effect of dietary fiber is, among other things, shorten the transit time of stool in the intestines, bind carcinogens and form protective chain fatty acids in the fermentation in the gut.