According to an article recently published in the International Journal of Cancer, a diet rich in folate, including green leafy vegetables, fruits and whole grains, and low in alcohol consumption may lower the risk of developing colorectal cancer.
Cancers of the colon and rectum, sometimes referred to together as colorectal cancer, are characterized by the presence of cancerous tumors in the colon or rectum, each part of the body’s digestive system. Researchers continue to work toward determining what factors may contribute to the development of colorectal cancer so that better treatments—and better strategies for prevention—can be produced and implemented. A person who has one or more characteristics or exposures, or risk factors, for a type of cancer has a higher chance to develop that type of cancer than a person who does not have these risk factors. Risk factors can be determined by studying the differences between persons who have and persons who do not have a type of cancer.Several risk factors have been suggested in association with colorectal cancer: age older than 40 years; having or having had intestinal polyps; having or having had inflammatory bowel disease; having or having had breast, ovarian, or endometrial cancer; having a history of colorectal cancer in one’s immediate family (genetic predisposition); having a diet high in fat, protein, calories, alcohol, and meat while low in calcium and folate; having a sedentary lifestyle; and smoking tobacco. As important as knowing which factors might increase the risk for colorectal cancer is knowing which characteristics or exposures, or protective factors, might reduce this risk. Some have speculated that higher intake of folate and methionine, in conjunction with lower alcohol intake, may confer preventive effects.
Folate, also known as folic acid, is a B-complex vitamin that helps in the metabolism of DNA and is available in many vegetables. Many studies have suggested that high folate levels appear linked to lower levels of certain types of cancer. Methionine is an amino acid that regulates the availability of folic acid in the body. Previous studies have suggested that people with a family history of colon cancer are less likely to develop colon cancer themselves if they have higher levels of methionine. Methionine is available naturally in meat, fish, beans, eggs, garlic and sunflower seeds.
A multi-center Italian study investigated the dietary habits of 1,953 patients with colorectal cancer and 4,154 cancer-free individuals. All subjects completed a questionnaire listing the types of food they regularly ate and their daily alcohol consumption. Light drinkers were defined as consuming less than one glass of wine daily, while heavy drinkers consumed at least two 12-ounce beers a day.
The researchers reported that the rate of colorectal cancer was 40% higher rate for heavy drinkers with diets deficient in folate and methionine. The main sources of folate in Italian diets were green leafy vegetables, whole grains and liver. Orange juice, beans and peas were also widely consumed foods that have high levels of dietary folate. Low levels of methionine were only slightly associated with colorectal cancer, while the combination of low methionine and folate levels were more stronger associated with higher cancer risk. According to the lead author in the study, people should “avoid drinking more than one or two drinks of alcoholic beverages a day” and include “lots of fruits and vegetables” in their diet.
Reference: La Vecchia C, Negri E, Pelucchi C, et al. Dietary folate and colorectal cancer.
International Journal of Cancer. 2002;102:545-7.