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By Dr. Sharon Gurm BSc, ND, Naturopathic Physician, Clinic Founder & Clinical Director

“Instead of cure, cancer prevention through diet and lifestyle changes is a more plausible goal.” – Dr. Ajay Goel, Ph.D   (Baylor Research Institute, Charles A. Sammons Cancer Center)

March is national colon cancer awareness month. Colorectal cancer ranks as the third most common cancer in North America and the third leading cause of cancer death.[1] So let’s talk about how you can keep your colon healthy and cancer-free!

Although colorectal cancer is one of the most common cancers in western countries, it may also be one of the most preventable ones. Prevention is largely achievable through diet, lifestyle factors (such as exercise and smoking avoidance), dietary supplements and appropriate screening (stool blood testing, colonoscopy).[2]

Looking at global epidemiological data, the incidence of colon cancer is highest in western countries, while in Africa and India the incidence is 10-15 times lower! Why such a discrepancy? When populations migrate from countries where there is a low rate of colorectal cancer, within 1-2 generations their incidence rates match that of their chosen residence.

Why would this be? The main factor is because the migrating populations eventually adopt the standard dietary habits of western countries and gradually detach from their traditional cultural foods and dietary patterns.

There is no question, based on scientific and clinical evidence gathered to-date, that diet is a major contributing factor to the incidence of colon cancer in North America. In fact, up to 80% of colorectal cancers are attributable to diet.[2] Specifically, those who consume diets high in animal fat have shown a significantly increased risk of developing colon cancer.[3]

Decrease your risk of colon cancer with a higher intake of fruits & vegetables

In a study conducted at Harvard University, researchers found the risk of colon cancer was 2.5 times higher in women who ate beef, pork or lamb as a main dish everyday, compared to those eating it less than once a month.[3]

The association between meat consumption and colorectal cancer is attributed to the formation of a carcinogenic compound known as ‘heterocyclic amines’, created when meat is cooked. High-meat diets in humans increase the level of nitrosatable material entering the colon, leading to an increase in fecal NOC’s (N-nitroso compounds or nitrosamines). NOC’s alter the DNA of colonic cells (in a dose-dependant manner), increasing the potential for development of cancerous cells. [2]

In addition, the more nitrogen that enters the colon, the more ammonia is produced as a by-product of metabolism. Ammonia is considered a carcinogen. [4]

In general, risk of all cancers are twice as high in individuals with low fruit and vegetable intake (at least the lower one‐fourth of the population) compared with those with high intake, even after control for potentially confounding factors.[5]

Furthermore, reports in the past few decades have concluded that higher intakes of dietary fiber, coupled with high intake of vegetables, reduce the risk of colorectal cancer.[6,7]

For colorectal cancer in particular, the evidence that a high fiber diet lowers risk is most conclusive of all the factors that have been studied. This makes perfect sense, when you consider that fiber helps bind and move toxic and carcinogenic compounds through the intestines faster, decreasing the time that these compounds contact the intestinal wall. Fiber can also act as a ‘pre-biotic’, which helps the growth of healthy bacteria in gut.

A diet high in fiber seems to be particular helpful for those who have or are prone to forming polyps in the colon – which is a significant and independent risk factor for colon caner.

Such research has been the impetus for global public-health recommendations to increase vegetable and fiber consumption in order to increase stool weight and thus decrease risk of large-bowel cancer and other large-bowel disorders.[6,7]

We should eat 25 grams of fiber daily to lower or colorectal cancer risk

How much fiber should you eat? Based on scientific findings, 25 grams of fiber daily should be your goal! Stay tuned for information on the best sources of fiber and just how much fiber content they contain. If you’re not already eating this much fiber, don’t be surprised how great you feel when you do – you may even shed a few unwanted pounds!

In 2006, Harvard University published results of a large-scale research review they conducted to assess the relationship between dairy consumption and cancer risk.[8] They found an overwhelming association with dairy consumption and higher rates of cancer, believed largely to be due to the concentrated hormones (namely estrogens) in milk. These findings were supported by another study published by Harvard University in 2012, showing that pasteurized milk product from factory farms is linked to causing hormone-dependent cancers.[9]

Cancer rates related to dairy can change very quickly with a public effort to initiate change. With this knowledge, the Harvard School of Public Health declared that dairy is not part of a healthy diet. Instead, they encouraged greater consumption of nuts, beans and fish for protein. They also suggested that fortified milk alternatives (such as almond, soy or rice), bok choy, collard greens and baked beans are safer ways of obtaining calcium from diet than through the consumption of dairy.

Results on dairy product consumption and colon cancer risk are conflicting. Some suggest a positive association, while others suggest a negative association. One of the few studies suggesting that dairy consumption reduces the risk of colorectal cancer was published in 2006. However, the study population was Swedish men, not North American men.

European regulations are different than that of Canada and the US. Hence, dairy products produced and sold in Europe do not contain as much or as many different hormones and other toxic compounds. It’s possible that fact plays a role in the conflicting observational data collected in studies on dairy intake and colorectal cancer.[10]

Fish is the one exception to the rule that animal fats are bad. A Harvard study found those who consume fish have a lower incidence of colorectal cancer.[3] Studies have found omega-3 fatty acids in particular are responsible for the protective effect.[11]

Wild salmon is the best choice, since it contains the least amount of mercury, dioxins and other toxic contaminants. The rest of your dietary fats should come primarily from plant sources of omega-3 and omega-6, such as pumpkin seed, flax seed, olive oil, hemp seed, grapeseed, coconut oil (a healthy ‘saturated’ fat), sunflower and sesame.

What about alcohol? Alcohol consumption increases the risk of colorectal cancer and the risk is even greater in those who have a genetic defect affecting an enzyme known as alcohol dehydrogenase.[12,13]

The worst culprit for colon cancer is beer, due to its high content of nitrosamines

The worst culprit for colon cancer is beer, due to its high content of nitrosamines, discussed earlier as a carcinogen compound. Many associate wine with good health. However, the tannins found in red wine are a potential carcinogenic compound. Red wine is often touted for its health-promoting properties due to the resveratrol (antioxidant) content in the grape skin. However, the evidence is pretty clear that those who consume little to no alcohol have a lower risk of colon cancer – and all cancers for that matter. The beneficial effects of wine (1 glass per day) appear to be limited to its protective effect on the heart. But the trade-off here is the increased risk for cancer.

Now that you’re well informed of dietary factors that influence your colon health and the risk of colorectal cancer, we hope you’re motivated to participate the next challenge of our Best Health Series!

Click here to begin your quest for a healthy colon!


  1. American Cancer Society. Cancer Facts & Figures 2012. Atlanta, GA: American Cancer Society; 2012.
  2. Bingham SA. Diet and colorectal cancer prevention. Biochem Trans Society. 2000; 28:12-16
  3. American Cancer Society. Colorectal cancer early detection.
  4. Tsujii, M., Kawano, S., Tsuji, S., Takei, Y., Tamura, K., Fusamoto, H. and Kamada, T. (1995) Carcinogenesis 16, 563–566
  5. Block G, Patterson B, Subar A. Fruits, vegetables and cancer prevention: A review of the epidemiological evidence. Nutrition & Cancer. 1992; 18(1): 1-29.[more references here]