Obesity also raises the risk of colorectal cancer. In fact, it is estimated that 3.2% of all new cases of cancer in the United States have an association with obesity. Obesity and overweight are also responsible for 14% of cancer deaths in men and 20% in women. The National Institutes of Health defines overweight as a body-mass index (BMI) of 25.0 to 29.9, and obesity as a BMI greater than 30. To calculate your BMI, divide your weight in pounds by your height in inches, then divide that result by your height in inches again. Multiply that result by 703. In other words, weight ÷ height ÷ height × 703.
It has been estimated that 70% of the cases of colorectal cancer in Western countries could be prevented through changes in lifestyle. While many lifestyle factors are mentioned in this article, the best path to successful prevention of colorectal cancer includes all of these factors. However, incorporating even a single lifestyle change is beneficial.
The influence of diet
Many studies have examined the connection between diet and the risk and incidence of colorectal cancer. While there are still many unknowns, it’s clear that following a nutritious diet high in fruits and vegetables and low in red and processed meats and saturated fat is likely to be beneficial.
Meat. A large study published in 2005 showed that a diet high in processed and red meat increases the risk of colorectal cancer. It additionally found that a high consumption of poultry and fish was associated with a lower risk.
Processed meats include bacon, bologna, ham, hot dogs, luncheon meat, salami, sausages, and other beef and pork products preserved by salting, smoking, or adding nitrites or nitrates. Red meat includes beef, pork, lamb, liver (including chicken livers), and veal. In the study, a high intake of red meat was defined as 3 or more ounces a day for men and 2 or more ounces a day for women.
The study did not determine the mechanism by which red or processed meat increases colorectal cancer risk. But the take-home message is clear: By decreasing the amount of processed and red meat in the diet and eating more fish and poultry, many cases of colorectal cancer could be prevented.
Other studies have shown that grilling meat — including red meats, chicken, and fish — at high temperatures can produce cancer-causing, or carcinogenic, compounds, among them chemicals known as heterocyclic amines. The longer and hotter the cooking method, the more compounds are formed. These compounds have been linked to colon cancer as well as to breast and prostate cancer.
Fruits and vegetables. Many studies have shown that a high intake of fruits and vegetables not only protects against colorectal cancer but also against many other types of cancer, cardiovascular disease, and Type 2 diabetes. Fruits and vegetables contain vitamins, minerals, fiber, antioxidants, and other nutrients. The allium vegetables — onion, garlic, scallions and leeks — have a strong protective effect against colorectal cancer. Green vegetables, carrots, and cruciferous vegetables also have a protective effect. Cruciferous vegetables, which include broccoli, cauliflower, cabbage, and Brussels sprouts, contain a chemical called sulforaphane, which protects against many kinds of cancer. Chlorophyll in green vegetables binds to cancer-causing chemicals — including the heterocyclic amines that are formed when foods are grilled — and forms a large molecule that is excreted from the body in feces rather than being absorbed.