A Highly Preventable Cancer

Karen Collins, MS, RD, CDN American Institute for Cancer Research

One renowned researcher estimates that 70 percent of colon cancers could be prevented with only moderate changes in diet and lifestyle. Current research points to several strategies you could employ to protect yourself against colon cancer development. Future research should be able to tell which of these inter-related strategies is most important for your particular needs.

One prime suspect now is insulin resistance. In this condition, higher levels of insulin circulate because the body is less responsive to it. Insulin and related growth factors seem to change cell processes in ways that promote the development of cancer. Insulin resistance could explain why inactive and overweight people, especially with excess weight around the waist, are more likely to develop colon cancer.

One new study looks more closely at the diet and finds excess calorie consumption to be the real culprit. Other studies suggest, however, that saturated fat and refined carbohydrates, which include sugars and refined grains, may be more damaging than other sources of calories.

Although physical activity does not change colon cancer risk in all studies, it is a key part of any risk reduction plan. The latest National Cancer Institute (NCI) review of steps to prevent colon cancer reports that activity lowers risk 40 to 50 percent on average.

Activity’s effectiveness might be related to its tendency to prevent weight gain, or directly affect insulin levels. The American Institute for Cancer Research (AICR) recommends an hour of moderate activity daily.

Frequent consumption of red meat or processed meat is a risk in many studies. Processed meat contains substances that can develop into carcinogenic compounds. Fatty red meat is high in saturated fat, which is the most damaging type of fat. Even lean red meat, however, can be high in cancer-causing substances called heterocyclic amines (HCAs), if well done or cooked at high temperatures, like frying, broiling or grilling. Meat consumption may be especially dangerous if your diet is low in vegetables.

Consuming enough calcium is the latest strategy to lower colon cancer risk. A recent study looked at the recurrence of colon polyps, which are noncancerous growths that can turn into cancer. Polyp recurrence was 29 percent lower with a higher consumption of calcium and vitamin D. Research presented at AICR’s most recent research conference suggested that calcium might be especially important for those with a high-fat diet. By binding fatty acids and bile acids – both of which promote cancer – in our digestive tract, calcium may protect the colon.

For a long time, fiber has been considered a vital colon cancer fighter. It was consistently significant in laboratory experiments and high in the diets of populations with low colon cancer risk. But now large studies that followed people for years cast doubt on this link. Perhaps, a particular type of fiber, like fiber from whole-grain breads and cereals, is significant. Or maybe fiber is important for some people. Whatever the case may be, eating an abundance of vegetables, fruits, whole grains and beans is still a wise strategy. The only difference is that these fiber-rich foods now seem more beneficial for the antioxidant vitamins and phytochemicals they contain. For example, vegetables high in folate, like leafy greens, seem to offer particular protection from colon cancer, especially for those who drink alcohol. Cruciferous vegetables, like broccoli and cauliflower, also contain phytochemicals that may prevent damage to colon cells’ DNA by stimulating enzymes that convert carcinogens to inactive forms.

The American Institute for Cancer Research (AICR) offers a Nutrition Hotline (1-800-843-8114) 9 a.m. to 5 p.m. ET Monday-Friday. This free service allows you to ask questions about diet, nutrition and cancer. A registered dietitian will return your call, usually within 48 hours. AICR is the only major cancer charity focusing exclusively on the link between diet, nutrition and cancer. The Institute provides education programs that help millions of Americans learn to make changes for lower cancer risk. AICR also supports innovative research in cancer prevention and treatment at universities, hospitals and research centers across the U.S. The Institute has provided more than $65 million in funding for research in diet, nutrition and cancer. AICR’s Web address is AICR is a member of the World Cancer Research Fund International.