(VESNA JOVANOVIC, n.d.)
We are already halfway through breast cancer awareness month so in this blog post, we are going to touch on the four cancers that represent nearly half of all new cases in Canada: lung, prostate, breast, and colorectal cancer. Likely most of us have had life experiences that connect us to cancer in some way, as it is the leading cause of mortality in Canada, responsible for 30% of all deaths.
Let’s talk about how these four cancers can be associated with dietary patterns. Starting with lung cancer, as is widely known, is most commonly caused by individual behaviours like smoking, as well as exposure to second-hand smoke. Less avoidable, environmental factors that can cause lung cancer include radon, asbestos, exposure to radiation and air pollution, among others. In the case of non-smokers, a high intake of fruits and vegetables has been shown to be a protective factor for some of these environmental contaminants. If you’re unsure of how much is the right amount, visit Canada’s new food guide for some recommendations, tips and recipes.
According to a meta-analysis conducted including 15 cohorts, there is significant evidence that the risk of prostate cancer can be increased by up to 7 percent with a higher intake of dietary calcium, specifically from dairy (400 g of dairy products per day). Interestingly, evidence that intake from other foods containing calcium can increase prostate cancer risk was not conclusive. Moreover, a high intake of fruits and vegetables is shown again to have protective properties against prostate cancer whereas a high total fat intake, animal fat intake and consumption of red meat were associated with increased risk of prostate cancer. Protective nutrients found in fruits and vegetables include lycopene found in tomatoes (especially those that have been heated), as well as antioxidants such as vitamin E and selenium, which were found to be associated with reduced risk.
Second to skin cancer, breast cancer is currently the most prevalent cancer amongst women in North America. In Canada, the incidence rate of breast cancer is an average of 27,400 women and about 5,100 die from it each year. In terms of diet, a high intake of red meat, in particular, shows a significant increase in the risk of breast cancer. Further, in a case-control study conducted in Connecticut with premenopausal women, high fibre intake was linked to the reduced risk of breast cancer.
This correlation, however, has not yet compared to the protection that dietary fibre offers for the prevention of colorectal cancer, which researchers have found can be prevented by dietary and lifestyle changes in up to 70% of all cases in the United States. Soluble fibres pass through the digestive system undigested, forming a gel-like substance that dilutes or adsorbs fecal carcinogens along the way, along with the many other benefits that fibres offer such as the reduction of transit time in our digestive system and increasing satiety. In the colon, soluble fibre is fermented by our gut bacteria resulting in the production of short-chain fatty acids, such as butyrate, which are found to have anti-proliferative effects on colonic polyps and the resulting cancerous cells. Both soluble and insoluble fibre can be found in intact fruits and vegetables, grains (particularly whole wheat), legumes and pulses. It is important that these foods are “whole” as fibres are reduced, if not eliminated, by intensive mechanical food processing, as in seen in juicing.
The mechanisms behind high intake of fruit, vegetables, grains and legumes offer protection against cancers due to synergies of their antioxidant properties and the presence of phytochemicals, supporting normal, healthy cellular growth and protection from harmful environmental factors, as well as pathogens in our food. Nutrition guidelines from the American Cancer Society recommend a diet with a heavy focus on plant foods, including five or more servings of fruits and vegetables per day, along with plenty of whole grains, legumes, nuts and seeds, while limiting the intake of red and processed meats.
The biggest takeaway from this article is that good diet quality combined with stress management and healthy coping mechanisms, regular physical activity while limiting or eliminating alcohol and/or tobacco use should help you navigate the trajectory to a more healthful life and reduce your risk of a clinical diagnosis of cancer. If you are worried that you may be at risk of developing cancer or have a family history of cancer, have a conversation with your family doctor and get a referral to speak to a dietitian to talk about how you can continue to decrease your risk of cancer through proper nutritional management.
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