Diet and nutrition may cut the risk of colon cancer, which kills more than 50,000 people each year in the USA, making it one cancer where preventative action may truly save your life.

Colorectal cancer is most common in countries with a typical “Western” diet: high in fat, calories, meat (especially red and processed meats), sugar, and refined grains, and low in fruits, vegetables, and whole grains.

The “heart healthy” diet, on the other hand, is good for the colon because it is naturally high in fiber which is believed to protect against colon cancer. Fiber - found only in plant foods - comes in two forms: soluble and insoluble. Insoluble fiber, found in whole grains and vegetables, increases stool bulk and helps prevent constipation. Chronic constipation increases the risk of colon cancer.

A recently released analysis of data collected in the ongoing Nurses’ Health Study has cast doubt on the role fiber plays in the prevention of colon cancer. While the study is well designed, and conducted by a respected team of researchers, it is by no means the last word on the subject. Concerns about the findings center on the fact that fiber consumption patterns were determined through a survey which asked participants to recall what, and how much of, various nutrients they had eaten. The questionnaires were updated every two to four years, which compounds concerns about the accuracy of participants’ memories.

Many experts believe a more definitive understanding of the role of fiber in cancer prevention will come through controlled clinical trials, comparing cancer rates in people who eat fiber-rich diets and those who do not. One such study, the Polyp Prevention Trial, is currently underway. In any case, a diet high in fruits, vegetables, and whole grains provides numerous important nutrients beyond fiber, and we are only beginning to understand all the benefits they provide.

High intakes of beta-carotene, calcium, and the B vitamin folic acid, all of which are abundant in the healthy diet, seem to protect against colon cancer. A yearlong study involving 70 people with a history of benign colorectal polyps determined that those who increased their consumption of low-fat dairy products to provide 1,500 mg of calcium daily experienced a reduction in the growth of abnormal cells. Vitamin C is protective, too, and vitamin D may also play a role. Cruciferous vegetables (such as broccoli, cabbage and cauliflower) contain other substances besides vitamins and fiber that may also reduce your risk.

New findings from the ongoing Nurses’ Health Study, involving some 89,000 women, indicate that those with high intakes of folic acid (above 400 micrograms a day) greatly reduce their risk of colon cancer. Over a 15-year period, women who took a daily multivitamin with folic acid were 75% less likely to develop colon cancer than those who did not take vitamins, even after accounting for other possible risk factors, such as family history of the disease, intake of red meat or alcohol, smoking, and physical activity. Foods that are particularly good sources of folic acid include asparagus, avocado, spinach, legumes (beans and peas), and enriched grains and cereals.

The bottom line: A healthy, varied diet is the best way to ensure optimum health and to protect against chronic conditions, including heart disease, cancer, and diabetes.