Final answer:
A diet high in fat and refined carbohydrates increases the risk of colorectal cancer by facilitating carcinogenic changes and increasing exposure to cancer-causing substances. Dietary fiber can help reduce the risk of tumor formation by hastening bile acid excretion and diluting the concentration of carcinogens. Following dietary recommendations to eat more fruits, vegetables, whole grains, and legumes and reduce processed and red meat intake can further lower the risk of colorectal cancer.
Step-by-step explanation:
A diet that is high in fat and refined carbohydrates increases the risk of colorectal cancer. High fat content results in an increase in fecal bile acids, which facilitate carcinogenic changes. Refined carbohydrates increase the transit time of food through the gastrointestinal tract and increase the exposure time of the intestinal mucosa to cancer-causing substances.
Dietary fiber and calorie restriction are two anti-carcinogen or anti-promoters that decrease the risk of tumor formation. One mechanism by which fiber acts is hastening bile acid excretion. Fiber also increases the rate of passage of materials through the colon resulting in decreased production and exposure of the colon to cancer-causing agents, ie dilutes the concentration of carcinogens.
The American Institute for Cancer Research, American Cancer Society, and National Cancer Institute provide dietary recommendations to reduce cancer risk which focus on eating more fruits and vegetables, whole grains, and legumes; reducing processed meat and red meat intake; and limiting alcohol intake. Fruits, vegetables, and whole grains are rich in fiber.