Colon cancer has been in the news as of late after the International Agency for Research on Cancer (IARC), which is part of the World Health Organization (WHO), concluded in late 2015 that processed meat can cause colorectal cancer in humans, classifying it as a Group 1 carcinogen.
Colorectal cancer, which includes both cancers of the colon and rectum, is the third most common cancer diagnosed in the U.S. (not including skin cancers). In 2016, it’s estimated there will be more than 95,000 new cases of colon cancer (and more than 39,000 cases of rectal cancer) diagnosed.1
Your colon, also known as your large intestine, plays an incredibly important role in your health. As food passes through your colon, liquid and salt are removed to prepare it for elimination.
Aside from helping to form, store and eliminate waste, your colon contains billions of bacteria, a healthy balance of which is essential for optimal health.
Colorectal cancer is the second leading cause of cancer deaths in the U.S., but, like many types of cancer, it is often preventable.
Research published in Pharmaceutical Research suggested that only 5 percent to 10 percent of cancer cases are due to genetic defects, while the rest are linked to environment and lifestyle factors.2
The researchers estimated that up to 35 percent of cancer-related deaths may be due to diet, another 30 percent due to tobacco, 20 percent due to infections and the rest due to other environmental factors including exposure to radiation, stress, physical activity levels and environmental pollution.
The American Institute for Cancer Research (AICR) also stated that about one-third of the most common U.S. cancer cases are preventable through a healthy diet, being physically active and maintaining a healthy weight.
In the case of colorectal cancer, the percentage that could be prevented via these lifestyle factors rises to 50 percent.3
Today can be the day you start making healthy changes to lower your risk of this potentially deadly disease. Top steps include the following.
1. Eat More Vegetables and Some Fruits
Vegetables contain an array of antioxidants and other disease-fighting compounds that are very difficult to get anywhere else – like magnesium.
Results from one meta-analysis indicated that for every 100-milligram increase in magnesium intake, the risk of colorectal tumor decreased by 13 percent, while the risk of colorectal cancer was lowered by 12 percent.4
The researchers noted magnesium’s anti-cancer effects may be related to its ability to reduce insulin resistance, which may positively affect the development of tumors.
Beyond magnesium, plant chemicals called phytochemicals can reduce inflammation and eliminate carcinogens, while others regulate the rate at which your cells reproduce, get rid of old cells and maintain DNA.
Vegetables are also one of the best forms of dietary fiber. Studies have repeatedly shown that people with higher vegetable intake have lower rates of cancer.5
Cruciferous vegetables may be particularly beneficial due to the sulforaphane they contain. Sulforaphene, a naturally occurring derivative of sulforaphne, has been found to suppress growth of colon cancer-derived tumors, for example.6
If you’re healthy, consuming some fruit in moderation may also be beneficial. According to one study, dried plums (i.e. prunes) may lower your risk of colon cancer by building your gut bacteria.7
2. Eat More Fiber
Dietary fiber has been associated with a reduced risk of colorectal cancer, particularly incident colorectal adenoma and distal colon cancer.8 Further, for every 10 grams of fiber you add to your daily diet, your risk of colon cancer decreases by 10 percent.9
A 2005 study similarly revealed that dried plums “favorably altered … colon cancer risk factors” in rats, possibly due to their high content of dietary fiber and polyphenolics.10
Fortunately, if you follow the tip above and eat more vegetables, you’ll naturally be eating more fiber from the best possible source — vegetables. Psyllium seed husk, flax seeds, hemp seeds and chia seeds also provide valuable sources of soluble and insoluble fiber.
3. Optimize Your Vitamin D Levels
Vitamin D deficiency is a risk factor for colorectal cancer. In one study published in the journal Gut, people with higher blood levels of vitamin D were less likely to develop colorectal tumors.11
This may be because vitamin D is beneficial for your immune system, which in turn may help to limit the growth of cancerous tumors. According to the researchers:12
“Evidence suggests protective effects of vitamin D and antitumour immunity on colorectal cancer risk.
Immune cells in tumour microenvironment can convert 25-hydroxyvitamin D [25(OH)D] [vitamin D] to bioactive 1α,25-dihydroxyvitamin D3, which influences neoplastic and immune cells
… High plasma 25(OH)D level is associated with lower risk of colorectal cancer with intense immune reaction, supporting a role of vitamin D in cancer immunoprevention through tumour–host interaction.”
Regular sun exposure, use of a high-quality tanning bed and/or supplementation with a vitamin D3 supplement can get your vitamin D levels into the optimal range of 50-70 ng/ml. You’ll need to monitor your levels to be sure you stay within this target range.
4. Avoid Processed Meats
Processed meats are those preserved by smoking, curing, salting, or the addition of chemical preservatives.
This includes bacon, ham, pastrami, salami, pepperoni, hot dogs, some sausages, and hamburgers (if they have been preserved with salt or chemical additives) and more. Particularly problematic are the nitrates that are added to these meats as a preservative, coloring and flavoring.
The nitrates found in processed meats are frequently converted into nitrosamines, which are clearly associated with an increased risk of certain cancers. AICR warns that "there is no safe threshold" for eating processed meats.13
5. Be Knowledgeable About Red Meat Consumption
Research suggests that people who eat the most red meat (in one study this was five ounces a day) have a 24 percent greater risk of colorectal cancer than those who eat the least.14
Red meat is likely not the problem in and of itself, however, but the way it’s cooked, and the source it comes from, likely play a role. Grass-fed beef, for instance, contains cancer-fighting compounds.
On the other hand, it’s known that glyphosate, the active ingredient in Roundup herbicide, can have a detrimental impact on healthy gut bacteria and is carcinogenic. CAFO animals are typically fed grains contaminated with glyphosate.
Red meat cooked at high temperatures (such as barbecued or fried) may also contain carcinogenic cooking byproducts like heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs).
When it comes to meats, I recommend eating organically raised grass-fed meats only and cooking them only lightly (rare, not well-done). For the record, I believe most people need some animal protein to be optimally healthy, but most eat far more protein than is necessary (or healthy).
There is convincing evidence that regular exercise can significantly reduce your risk of colon cancer.15 One study revealed that physically active men and women have about a 30 percent to 40 percent reduction in the risk of developing colon cancer compared with inactive persons, for instance.16
For starters, exercise drives your insulin levels down, and controlling insulin levels is one of the most powerful ways to reduce your cancer risk. It's also been suggested that apoptosis (programmed cell death) is triggered by exercise, causing cancer cells to die.
Exercise also improves the circulation of immune cells in your blood. The job of these cells is to neutralize pathogens throughout your body, as well as destroy precancerous cells before they become cancerous. The better these cells circulate, the more efficient your immune system is at defending itself against infections and diseases like cancer.
7. Maintain a Healthy Weight and Control Belly Fat
A number of studies have linked obesity to an increased risk for about a dozen different cancers, including cancer of the colon. In a 2014 study that analyzed data from more than 5 million people over the age of 16, every 11-pound increase in body weight was associated with an increased risk for 10 types of cancer.17
If you’re overweight or obese, even small amounts of weight loss can lead to significant benefits for your health. In terms of cancer prevention, losing excess belly fat is particularly important, as belly fat is linked to an increased risk of colon cancer regardless of your body weight.
8. Limit Your Alcohol Intake and Quit Smoking
Both excessive alcohol intake and smoking are associated with an increased risk of colorectal cancer. When it comes to alcohol, I generally define "moderate" alcohol intake (which is allowed in the beginner phase of my nutrition plan) as a 5-ounce glass of wine, a 12-ounce beer or 1 ounce of hard liquor, with a meal, per day.
As you progress further in the nutrition plan, I do recommend eliminating all forms of alcohol. If you’re a smoker, you can find tips for quitting here.
9. Eat Garlic
Garlic has been shown to kill cancer cells in laboratory studies, as well as shown promise when consumed via your diet. One study showed that women who regularly ate garlic (along with fruits and vegetables) had a 35 percent lower risk of colon cancer.18
Those who consume high amounts of raw garlic also appear to have a lower risk of stomach and colorectal cancers.19 Furthermore, among people with inoperable forms of colorectal, liver, or pancreatic cancer, taking an extract of aged garlic for six months helped to improve immune function, which suggests it may be useful for helping your immune system during times of stress or illness.20
When you add raw garlic in your diet the fresh clove must be crushed or chopped in order to stimulate the release of an enzyme called alliinase, which in turn catalyzes the formation of allicin.
Allicin, in turn, rapidly breaks down to form a number of different organosulfur compounds. So to “activate” garlic’s medicinal properties, compress a fresh clove with a spoon prior to swallowing it, chop it finely to add to a salad, or put it through your juicer to add to your vegetable juice.
Download Interview Transcript
Men and women over the age of 50 at average risk of colorectal cancer are typically advised to get screened either by flexible sigmoidoscopy every five years, or by colonoscopy every 10 years. But are these screening tests safe and necessary? I’m over 60, and I’ve never had a colonoscopy and have no plans of ever getting one.
While I believe they can be valuable as a diagnostic tool, I feel confident that with my diet (which includes daily amounts of raw turmeric) and lifestyle it’s highly unlikely I would develop colon cancer.
But for many people who are at higher risk, colonoscopies may be an effective strategy. Colon cancer grows very slowly, and it’s one of the top leading cancers that kill people, so early detection is important. You could opt for an annual guaiac stool detection test — which checks for hidden blood in your stool — but this test produces many false positives, and the latest evidence suggests this test doesn’t work very well.
Another alternative is to get tested by flexible sigmoidoscopy every five years. It’s similar to a colonoscopy but uses a shorter and smaller scope, so it cannot see as far up into your colon. On the upside, it’s associated with fewer complications. Ultrasounds have also proven to be of value. Overall, visual inspection is the most reliable way to check for colon cancer, and this is what a colonoscopy allows your doctor to do.
If polyps are found in their early stages, your doctor can simply snip them off right then and there. So a colonoscopy is not only a diagnostic tool, it can also serve as a surgical intervention. They take a picture of the polyp, clip it, capture it, and send it to biopsy. It could save your life, and it’s definitely something to consider. However, be aware that about one in every 350 colonoscopies do serious harm. The death rate is about one for every 1,000 procedures.
Further, about 80 percent of endoscopes are cleaned using Cidex (glutaraldehyde), which does NOT properly sterilize these tools, potentially allowing for the transfer of material that could easily lead to infection. Asking what solution is used to clean the scope is a key question that could save your life. Make sure it’s been sterilized with peracetic acid to avoid potential transfer of infectious material from previous patients.