*3.2.1 Mechanisms*

Dietary fibres are fermented in the bowel by colonic microbiota to form shortchain fatty acids, such as butyrate and propionate (**Figure 3**), which have been reported to have anti-proliferative potential by inducing apoptosis and arresting of cell cycle and differentiation, and chronic inflammatory process inhibition [6, 24]. Dietary fibres can also increase faecal bulk or stool weight and frequency [24, 25], which could reduce the ability of faecal mutagens to interact with mucosa cells [24]. Examples of these are the insoluble fibres such as nuts, wheat bran, whole-wheat flour, beans, and vegetables including cauliflower, green beans and potatoes. Dietary fibres could also reduce intestinal transit time, decrease production of secondary bile acids, and reduce insulin resistance.
