Colon Cancer: Nutritional Considerations

In population studies, the following factors are associated with reduced risk of colon cancer:

• Avoiding or limiting meat consumption: Higher intake of processed red meat appears to increase the risk of colon cancer. This may be due to the presence of nitrosamines and polycyclic aromatic hydrocarbons, which are suspected carcinogens.
  
  In the European Prospective Investigation into Cancer and Nutrition (EPIC) study, individuals who ate at least 160 grams per day of red or processed meat had a 70 percent greater risk for colorectal cancer. In the Cancer Prevention Study II (CPS II), individuals who ate the highest amount of red meat and processed meat were at 50 percent greater risk for colon cancer and a 70 percent increased risk of rectal cancer.
  
  Although white meat may carry a lower risk than red meat, a study of Seventh Day Adventist men found that eating white meat more than once per week was associated with more than three times the risk compared with people who abstained from eating white meat.
  
  Further, the high cholesterol contained in animal products may increase the risk of colon cancer.
  
  In contrast, plant–based and vegetarian diets are associated with lower incidence of colon cancer, probably due to the absence of meat and to the inclusion of protective plant constituents, as explained below.
• Avoiding or limiting alcohol use: Several studies show that alcohol consumption (at least one drink per day) is independently associated with the risk of colon cancer.
• Increased fiber intake: Studies on dietary fiber and colorectal cancer risk have yielded conflicting findings. Some studies show that fiber reduces the risk of colon polyps, which are precancerous growths. However, a recent study found that the reduction in risk associated with high dietary fiber intake was small.
• B vitamins may reduce the risk of colon cancer: Folic acid, found in leafy green vegetables, beans, and whole grains, plays an important role in the maintenance of DNA, the genetic material inside our cells. Some evidence suggests that individuals who eat the most folate have as much as a 40 percent lower risk for colon cancer.
  
  Similarly, vitamin B6 is involved in DNA processes and other important body functions. Studies have shown that individuals who consume the highest amounts of vitamin B6 may have a reduced risk for colon cancer. Healthful sources include beans, nuts, legumes, whole grains, and fortified breads and cereals.
• Vitamin E may reduce the risk of colon cancer: Evidence has suggested that eating one–fourth of an ounce of nuts per day–an excellent source of vitamin E–may protect against colon cancer, particularly in women. The lower risk is attributable to food sources of vitamin E, but not vitamin supplements. Higher intakes of vitamin E–rich foods, such as nuts, seeds, and wheat germ, appear to reduce risk significantly in people younger than 65.
• Calcium and vitamin D may reduce the risk of colon cancer: Higher intakes of both calcium and vitamin D are associated with lower risk for colorectal cancer and may decrease the risk of recurrence. A lower risk for colon cancer has been found in persons who ingested 700 mg per day of calcium, compared with those who have lower intakes; however, higher intakes did not increase the benefit.