Lower your risk for colon cancer or its recurrence with diet now!
by Belle McCaleb – originally published in InnerSelf Magazine
According to Vargas and Thompson colorectal cancer (CRC) is estimated to kill approximately 600,000 people annually worldwide and is the third most common cancer in men and second most common in women. Furthermore the link between diet and nutrition is strong and is thought to explain as much as ½ of the worldwide incidence1.
In order to lower your risk for this prevalent cancer or its recurrence it is important to know what dietary factors increase risk and what factors decrease risk.
Decrease or avoid red and processed meat
Both red and processed meats (nitrate-preserved) are high in DNA damaging compounds. In addition red meat is high in heme (an iron containing substance) that promotes these damaging compounds and is an independent risk factor for colorectal cancer. And the risk further increases with meat cooked til blackened or charbroiled as this forms additional carcinogens called heterocyclic amines. In 2011 Chan et al2 found CRC risk increased by 29% per 100 g/day red meat consumed and by 21% per 50g/day of processed meat consumed.
Decrease or avoid alcohol
Alcohol consumption is linked to increased risk and this may be due to direct effects on DNA, increased intracellular oxidation and depletion of folate (a B vitamin). Folate is required for protecting DNA integrity. The risk appears to be dose dependent with heavier drinkers having increased risk. The risk is also higher in people who have a diet low in folate and an amino acid called methionine. Folate is found in green leafy vegies and methionine in protein foods such as fish, eggs, chicken, whole grains, nuts and seeds. Some people have a genetic variation and lack the enzyme activity necessary for optimal folate utilisation (the variation is called an MTHFR genetic polymorphism and can be tested for). It is possible that this population is more at risk for alcohol induced CRC and they may consider supplementation with a metabolically active form of folate which overcomes the problem.
Decrease animal fat
Animal fats initiate the release of an inflammatory cell signalling molecule, prostaglandin E2 (a known mechanism of CRC). They also modify bile acid metabolism and gut flora making the colon a toward a more cancer friendly environment. In 2010 a large study, called the DASH study, found a 20% reduction in the risk of CRC in participants adhering to a low animal fat intake diet as part of a dietary program for hypertension prevention.3
Decrease sugar intake
Sugars and refined carbohydrates are quickly converted to glucose in the body and stimulate the release of insulin and insulin like growth factor (a promoter of cancer growth). A 2014 study by Fuchs et al4 found intake of sugar sweetened beverages increased the chance of colorectal cancer recurrence and death, particularly in overweight and inactive cancer patients.
Increase fruits and vegetables
The European Prospective Investigation into Cancer and Nutrition (EPIC) which involved 470,000 participants found a 14% risk reduction for colorectal cancer and a 24% risk reduction for colon only cancer in the individuals who consumed the most fruit and vegetable.5 This is likely due to the fact that fruits and vegetables have many antioxidants, fibre and other phytochemicals with anti-tumour actions. Phytochemicals such as sulforaphane (broccoli), indole-3-carbinol (cabbage), diallyl sulfide (garlic) and ellagic acid (strawberries) protect normal cells from cancer initiation. Whereas phytochemicals such as curcumin (turmeric), epigallocatechin (green tea), resveratrol (red grapes), lycopene (tomatoes), anthocyanidins (blueberries), limonene (citrus) and proanthocyanidins (cinnamon, cranberries, blueberries) prevent tumor promotion and progression. A study in 2000 by Slattery et al6 found the carotenoid, lutein, found in spinach, broccoli, lettuce, tomatoes, oranges, carrots, celery and green leafies, was inversely associated with colon cancer in both men and women.
Increase whole grains
Whole grain consumption is associated with a reduced cancer risk of the colorectum whereas refined grain intake is associated with an increased risk. The hypothesis is the high fibre content in whole grains may improve the stool quality and increase stool transit time reducing exposure to potential carcinogens. In addition the fibres act as prebiotics which promote cancer-protective microflora and their activities. Whole grains as opposed to refined grains are lower in their glycaemic index and have a less stimulatory effect on the release of insulin and insulin like growth factors (a cancer promoter in excess). Whole grains are also a rich source of methionine and folate that are important for DNA health as explained above.7
Selenium is an important CRC preventor. It is important in protecting DNA, inducing cancer cell death as well as having roles in immunity, thyroid function and insulin signalling. In locations where selenium is rich in the soil food sources include alfalfa, brazil nuts, cashews, eggs, organ meats, tuna, oysters, broccoli and onions. However, some soils are very selenium poor (as is the case in Australia) therefore selenium content in food may be minimal. In this case selenium supplementation is worth considering.
Increase calcium & Vitamin D
Calcium & Vitamin D have demonstrated anti-tumour activity. Calcium helps bind pro-carcinogenic substances in the colon and inhibits cell proliferation and promotes healthy cellular differentiation. Calcium supplementation may be preferable to high dairy consumption due to the high fat content of dairy and other possible issues such as estrogen content. CRC cancer is related to estrogen exposure although the mechanism is unclear. Other sources of dietary calcium include almonds, broccoli, buckwheat, egg yolk, figs, sesame seeds, turnips and green leafies.
Vitamin D also has demonstrated anticancer and immune boosting capacities and is often found to be low in the Australian population due to the “slip, slop, slap” anti-melanoma campaign and other factors. Even if you do get alot of sunlight you may be low as Vitamin D must be activated twice in the body and some people are not efficient in this conversion. It is advisable to check your blood levels and aim for a level over 100. Food sources are very limited and supplementation is recommended if you are low.
Aim for a plant based diet with a variety of vegetables, fruit, whole grains, nuts & seeds. Use animal product sparingly if at all – eggs, fish and a bit of dairy are ok if sourced from organic or low toxicity sources. Juice vegetables and a bit of fruit to get a big hit of anti-cancer nutrients daily but eat them raw and lightly cooked as well for the fibre. Consider a hair mineral analysis to assess your mineral status, particularly selenium if you live in Australia. Get your Vitamin D level checked and if low consider supplementation. According to the current research following these guidelines will help you avoid CRC or its recurrence.
1Vargas J, Thompson P Diet and Nutrient Factors in Colorectal Cancer Risk Nutr Clin Pract October 2012 vol. 27 no. 5 613-623
2 Chan AT, Giovannucci EL. Primary prevention of colorectal cancer. Gastroenterology. 2010;138(6):2029-2043.e2010.
3 Fung TT, Hu FB, Wu K, Chiuve SE, Fuchs CS, Giovannucci E. The Mediterranean and Dietary Approaches to Stop Hypertension (DASH) diets and colorectal cancer. Am J Clin Nutr. 2010;92(6):1429-1435
4Fuchs, M et al Sugar-sweetened beverage intake and cancer recurrence and survival in CALGB 89803 (Alliance);PLOSone.org; 2014 DOI 10.1371
5 Aune D, Lau R, Chan DSM, et al. Nonlinear reduction in risk for colorectal cancer by fruit and vegetable intake based on meta-analysis of prospective studies. Gastroenterology. 2011;141(1):106-118.
6 Slattery M et al, Carotenoids and colon cancer 1,2,3,4; Am J Clin Nutr 2000;71:575-582
7Grosso G et al, Mediterranean diet and cancer: epidemiological evidence and mechanism of selected aspects, BMC Surgery, 2013;13(Suppl):514