Gastrointestinal System Disorders Q 151

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Which of the following diets is most commonly associated with colon cancer?

  

    A. Low-fiber, high fat

    B. Low-fat, high-fiber

    C. Low-protein, high-carbohydrate

    D. Low carbohydrate, high protein

    

    

Correct Answer: A. Low-fiber, high fat

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A low-fiber, high-fat diet reduces motility and increases the chance of constipation. The metabolic end products of this type of diet are carcinogenic. A high-fat, low-fiber diet is implicated in the development of colorectal cancer. Specifically, people who ingest a diet high in saturated animal fats and highly saturated vegetable oils (eg, corn, safflower) have a higher incidence of colorectal cancer.

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Option B: A low-fat, high-fiber diet is recommended to prevent colon cancer. The ingestion of a high-fiber diet may be protective against colorectal cancer. Fiber causes the formation of a soft, bulky stool that dilutes carcinogens; it also decreases colonic transit time, allowing less time for harmful substances to contact the mucosa. The decreased incidence of colorectal cancer in Africans is attributed to their high-fiber, low–animal-fat diet.

Option C: Saturated fats from dairy products do not have the same carcinogenic effect, nor do oils containing oleic acid (eg, olive, coconut, fish oils). Omega-3 monounsaturated fatty acids and omega-6 monounsaturated fatty acids also appear to be less carcinogenic than unsaturated or polyunsaturated fats. In fact, epidemiologic data suggest that high fish consumption may provide a protective effect against the development of colorectal cancer. Long-term diets high in red meat or processed meats appear to increase the risk of distal colon and rectal cancers.

Option D: Increased dietary intake of calcium appears to have a protective effect on colorectal mucosa by binding with bile acids and fatty acids. The resulting calcium salts may have antiproliferative effects, decreasing crypt cell production in the mucosa. A double-blind placebo-controlled study showed a statistically significant reduction in the incidence of metachronous colorectal adenomas.

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