Colon cancer is the second leading cause of cancer-related death in the world and the most common cancer in males and second most common cancer in females.
Researchers have established numerous environmental factors that increase our risk of its development. In fact, we now know that up to 70 percent of colon cancer cases are avoidable with dietary and lifestyle changes.
To understand the impact of external factors on the development of colon cancer, we can look at the vast variations in cancers around the world. Take lung cancer, for example. Lung cancer rates vary by a factor of 10 around the world. This huge variation in rates shows us that there must be an external cause at play and that this disease does not occur at random. This is true, of course, since we know that smoking is responsible for 90 percent of lung cancer causes.
Now, let’s look at colon cancer.
Would you be surprised to find out that there is an even BIGGER variation around the world for colon cancer? Colon cancer doesn’t occur randomly, either. There are known and unknown factors that cause it. Perhaps our colons accumulate carcinogens from our food in the same way that our lungs collect them from tobacco?
Let’s take a closer look at the dietary factors that are associated with reducing our risk for this disease.
Avoiding red and processed meat intake
The World Health Organization classifies processed meat as a Grade 1 carcinogen (meaning it causes cancer in humans) and red meat as a “probable” carcinogen to humans. Researchers at the International Agency for Research on Cancer (IARC) have stated that colon cancer risk increases by 17 percent per 100 grams of red meat consumed daily and 18 percent for every 50 grams of processed meat consumed daily.
Studies show that individuals with a higher intake of red meat have an approximately 20-30 percent higher risk for colorectal cancer than those with lower intakes of red meat. On the contrary, plant-based protein is associated with a reduced risk for colorectal cancer.
What might explain the link between meat intake and colon cancer risk? One explanation stems from the presence of carcinogenic compounds found in meat. These include nitrosamines (found in cured meats), polycyclic aromatic hydrocarbons, heterocyclic amines (created by cooking muscle tissue), and heme iron (which can act as a pro-oxidant in the body). These compounds can cause cells to mutate and multiply in the epithelium of the colon and initiate cancer development. Moreover, animal protein can putrefy in the colon, leading to ammonia production, which is linked with colon cancer. There are also numerous viruses that are known to cause cancer in animals and may be passed down to humans- these are present in poultry. Lastly, the dangerous compounds called dioxins present in fish and eggs may contribute to colon cancer risk.
Moreover, foods high in saturated fat, cholesterol, and animal protein are also associated with elevated colorectal cancer risk. High intakes of saturated fat stimulate the production of carcinogenic secondary bile acids in the colon (compounds formed by our gut bacteria when they metabolize bile). Animal protein intake is also associated with an increase in insulin-like growth factor (IGF-1), which is a growth hormone that has been shown to promote cancer cell growth. Consuming sources of animal protein (meat, dairy, and eggs), as well as refined sugar, elevates levels of IGF-1 in the body.
Maintaining a healthy weight
A meta-analysis of over 16,000 cases of colorectal cancer drew the conclusion that the risk for colorectal cancer increased by 4 percent for every 5 kg of body weight gained as an adult. Individuals who gained approximately 30 lbs experienced a 22 percent increased risk compared with individuals who maintained their weight. Both obese and underweight patients had significantly worse cancer-specific and overall mortality than patients who were normal weight or slightly overweight.
Consuming a fiber-rich diet
Studies show that high-fiber intake protects us against colorectal cancer.
A meta-analysis found a 12 percent lower risk for colorectal cancer in highest versus lowest consumers of total dietary fiber, and consumption of three servings per day of whole grains was also associated with a 17 percent lower risk. In a meta-analysis of 19 prospective studies of 12,000 -16,000 cases of colorectal cancer and approximately 1.7 million individuals, the risk for colorectal cancer was roughly 10 percent less for those who consumed the most fruits and vegetables in comparison to those who consumed the least. Similarly, a meta-analysis of cohort studies including nearly 2 million people concluded that the risk for individuals consuming the highest amount of legumes was about 10 percent less than for those consuming the least amounts. A systematic review and meta-analysis also found a roughly 25 percent reduction in risk for colorectal cancer in individuals with the highest intake of nuts. The Multiethnic Cohort Study of nearly 200,000 women and men showed a 40 percent lower risk for colorectal cancer in men who ate more than 35 grams of fiber per day, compared with those who ate roughly 13 grams per day.
Studies show that for every 10 grams of fiber consumed per day, we get a 10 percent reduction in colorectal cancer risk.
The most well-established mechanism of the capacity of fiber in reducing colorectal cancer risk stems from the ability of insoluble fiber to reduce the concentrations of secondary bile acids in the colon, which can promote cancer development.
Other potentially preventative effects of fiber-rich foods may be related to the phytonutrients that are only present in plants, such as carotenoids, sulfur-containing compounds, and flavonoids. Certain foods are specifically protective against colorectal cancer, including beans, berries, broccoli, carob, coffee, apples, turmeric, cranberries, sweet potatoes, nuts, lemon rind and seeds. The resistant starch found in plant foods like beans, lentils, green bananas, and uncooked oats can block the accumulation of potentially harmful by-products of animal protein metabolism in the colon.
The protective effects of such phytonutrients may indicate that fiber intake is just a marker for healthier eating, since it is only found in unprocessed plant foods. Therefore, the protection afforded by high fiber diets may derive from whole food plant-based nutrition rather than the fiber itself.
Limiting Alcohol Intake
Heavy alcohol consumption poses a risk for colorectal cancer. A 2015 review showed that consumption of over 30 grams of alcohol per day is significantly associated with an increased risk for colorectal cancer.
A study that followed 489,706 men and women (the NHI-AARP Diet and Health Study) over 10.5 years showed that individuals with a higher coffee intake (four cups a day or more), were associated with a significantly lower risk for colon cancer when compared to non coffee drinkers.
Does that mean we should all be drinking over four cups of a coffee a day? That depends. Research shows that there are health risks to consider. For example, high intake of unfiltered coffee (espresso or boiled) has been shown to increase cholesterol levels . Some studies have also shown that for people with a genetic mutation that slows the breakdown of caffeine by the liver, two or more cups of coffee per day can raise heart disease risk.
Let’s also not forget that the coffee is a stimulant and can therefore cause anxiety, heart palpitations, elevated chronic pain symptoms, and sleep disruptions in some people. It is also a diuretic and therefore causes water to be flushed out of the body. With water, minerals are also flushed out, such as calcium and magnesium. Moreover, coffee can raise blood pressure levels and can also enhance symptoms of gastrointestinal disorders like irritable bowel syndrome.
To wrap it up
We are far more in control of whether we develop colon cancer than we might think. We can certainly control our dietary input- at least three times a day! Multiple studies have demonstrated that plant-based dietary patterns may be beneficial in the prevention of colon cancer. In fact, plant-based diets are linked with a lower incidence of colon cancer. The positive effects of a plant-based dietary pattern are most likely due to the absence of meat as well as the presence of protective plant compounds.
Shifting to a plant-based diet is easier than you might imagine. Start by making small changes on a daily basis and remember that the goal is progress, not perfection.
For example, swap out cow’s milk for a plant-based alternative like almond milk in your morning oatmeal or cereal. Replace your usual chicken dinner with a plant-based source of protein, like tempeh, grilled tofu, or beans. In addition to replacing animal-based foods with plant-based foods, make sure to consume plenty of vegetables and fruits, as these are the most protective foods on the planet when it comes to cancer. To easily add veggies to your meals, try these tips:
- Make a nest of leafy greens (like spinach or kale) on which you put your food
- Use collard greens instead of tortillas in a wrap
- When cooking pasta, add chopped greens to the pot 4 minutes before the pasta is done- drain the pot and just add sauce!
- Blend mixed greens or other veggies (like broccoli, cauliflower, or carrots) into your pasta or pizza sauce
- When consuming a cooked meal (like a stir fry or pasta dish), mix in some finely diced raw veggies (tomatoes, celery, red onion, or bell peppers)
- Consume sprouts (alfalfa or broccoli)- these pack a nutritional punch for a fraction of the volume consumed (however do not contain the high fiber content found in the adult plants)
- Always add a side salad to your lunch or dinner, or simply add some plain leafy greens to your meal! Better yet, make a huge salad the main dish for your lunch or dinner
- Substitute spiralized zucchini, carrot, or yam for pasta
- The secret is in the sauce- to make eating raw or steamed veggies more palatable and FUN, make a delicious oil-free dressing and use it as a dip or sauce (try a tahini garlic or peanut sauce)
Remember- dietary changes are a process and not an overnight change. Be gentle with yourself, celebrating small changes along the way. The realization that your health is your greatest wealth is the most powerful tool in shifting to and maintaining a healthy lifestyle.