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2 Main Causes of Colorectal Cancer and How to Prepare For a Colonoscopy

If anyone among your parents, siblings, or children have had colorectal cancer, it's generally prudent to undergo periodic colonoscopies as a screening measure. How often you have a colonoscopy depends on your overall health status and the quality of your bowel movements, so be sure to let your physician know what your diet and lifestyle look like as you decide on a screening schedule.

I've always maintained that screening for disease is entirely different from preventing disease via one's daily choices, but in the case of colorectal cancer, early detection via a colonoscopy will significantly increase your chances of staying well with appropriate treatment.

What Is Colorectal Cancer And How Does It Develop?

Colon cancer is cancer of the large intestine, also called the colon, which is the lower part of your digestive tract. The very last section of the colon is where rectal cancer can occur. Together, cancers of the colon and rectum are referred to as colorectal cancer.

Colorectal cancer develops via a gradual accumulation of genetic mutations and other abnormalities that occur in the cells that line the colon and rectal walls. These mutations and abnormalities are thought to be caused by repeated exposure to toxins that are on their way to being eliminated from the body via stools.

Studies have found that on average, a malignant tumor in the colorectal region has a little less than a hundred genetic mutations which take about six decades to accumulate. The mutations that accumulate during the first five of these decades are enough to create a polyp, and additional mutations that occur over another decade is what transforms about one out of every 100 polyps into a malignant mass.

So why do some people develop colorectal cancer in their 30s while others live into their 90s and beyond without ever developing cancer in their digestive tract? Part of the answer lies in genetic disposition - we are all born with varying capacities to ward off mutations as we are exposed to toxins.

But there's no question that our risk of accumulating mutations that cause polyps and malignant masses is directly related to a number of environmental factors, the two most important ones being:

  • Exposure to Heterocyclic Amines (HCAs) and Polycylic Aromatic Hydrocarbons (PAHs)

    Both of these groups of chemicals are formed when flesh meats are cooked using high temperature techniques like grilling over an open flame, deep-frying, and pan-frying on high heat. Studies have shown that HCAs and PAHs are mutagenic. (1)

    Please note that PAHs are also abundant in smoked meats, cigarette smoke, and vehicle exhaust fumes.

  • Exposure to Alcohol

    The four main ways that ingestion of alcohol may increase risk of colorectal cancer are:

    1. Formation of acetaldehyde, which comes from breakdown of ethanol in alcohol. Acetaldehyde is classified as a toxin that is a probable human carcinogen, capable of damaging DNA.

    2. Production of reactive oxygen species, which are chemically reactive molecules that can damage DNA via oxidation.

    3. Impairment of breakdown and absorption of cancer-fighting nutrients like vitamin C, folate, vitamin D, and carotenoids.

    4. Exposure to carcinogenic contaminants that are byproducts of alcohol formation, phenols and nitrosamines being the two major groups.

Cucumber and Celery Juice, Broth, and Water to Stay Hydrated

Moving on to how to prepare for a colonoscopy, there's no way around clearing out the colon by inducing diarrhea. Conventional solutions for clearing out the colon cause diarrhea without substantial dehydration of the rest of your tissues.

Emptying the colon is essential to reducing potential complications during a colonoscopy. Ideally, an empty colon will allow for an efficient evaluation and detection of smaller polyps and lesions that might otherwise be missed.

Your physician should provide guidance on any medications that you might be taking, including aspirin, as well as what type of diarrhea-inducing solution he or she prefers you use.

Standard prep involves cessation of solid foods one to two days before your colonoscopy. Once you stop with solids, you'll want to stick with water, clear broth, and relatively clear vegetable juices - my recommendation for most clients is a mix of 80% cucumber and 20% celery juice.

When you take the laxative solution prescribed by your physician, it's best to stay at home near a bathroom. If you have an especially sensitive palate, consider using a straw to take the solution straight back to your oropharynx, thereby minimizing contact with the taste buds that line your tongue.

Thinking beyond periodic screening via colonoscopies, please remember that in almost all circumstances, risk of colorectal cancer is lowered with regular consumption of fresh vegetables, fruits, and legumes, regular exercise, and regular restful sleep.


1. Cross AJ, Sinha R. Meat-related mutagens/carcinogens in the etiology of colorectal cancer. Environmental and Molecular Mutagenesis 2004; 44(1):44–55.

Related Article:

How to Have Healthy Bowel Movements


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I added coconut water.
Homemade vegetable broth.
Ate Very light, easily digested foods 2 days prior to the prep day.

Dear Dr. Kim, I've been wondering more and more lately just how much of cancers are really caused by genetics instead of lifestyle. It seems to me that if mom and dad ate a lot of processed foods, drank and smoked, and didn't get much exercise then the children who were raised the same way would get the same diseases. The studies look at that and say it's genetic when it's really lifestyle. We have very little cancer in our family tree, except for an aunt on my dad's side who smoked like a chimney and died from lung cancer, and my dad who died a little over a year ago from prostate cancer. He drank a lot of alcohol, would not exercise much and ate badly. He was obese,had high blood pressure from in his early 50s, then had a heart attack when he was 65, then cancer. We knew all this was coming. What do you think?