Colon Cancer: A Deep Dive on Diet, the Microbiome and Colonoscopies

Colon Cancer: A Deep Dive on Diet, the Microbiome and Colonoscopies

Adapted from episode 102 of The Perfect Stool podcast hosted by Lindsey Parsons, EdD, Gut Health Coach, and edited for readability.

Today, I’m going to be talking all about colon cancer, its prevention, colonoscopies, endoscopies and diet changes to consider if you have a colon cancer diagnosis. I thought this topic might be important because I do see a number of clients who have gut health issues but haven’t yet been to see a gastroenterologist, so I wanted to highlight when and if that is recommended. 

One of the most prevalent health risks for men and women alike as they head into middle age is colon cancer. Colorectal cancers are the third-most-commonly diagnosed form of cancer in the United States and they typically begin with the benign growth of polyps in the colon or rectum. Polyps are an abnormal accumulation of tissue on the inner membrane of the large intestine (aka the colon), which, again, are not cancerous from their inception. However, if left unattended for months or years on end, these polyps can mutate into cancerous growths and become colon cancer. 

What are some symptoms of colon cancer?

Symptoms of colon cancer include persistent changes in bowel movements, including constipation, diarrhea and narrow stools, rectal bleeding or dark brown or black stool from bleeding coming from further up in the intestines, a feeling of incomplete elimination, chronic abdominal pain or cramping, unexplained weight loss, unexplained anemia, or even fatigue and general weakness. Unfortunately, once you’ve moved from benign polyp to symptomatic colon cancer, you may already have metastasized cancer cells in your colon, which would necessitate a more severe line of treatment. However, if caught at an early stage, polyps can be removed, and then there are many diet and lifestyle changes you can implement that contribute to staving off colon cancer. So it’s important, before attacking any functional GI issues with a functional medicine provider or a gut health coach like me, to get screened for colon cancer with a gastroenterologist if you’ve had any symptoms like the ones I just mentioned. 

How can I prevent colon cancer?

In the past half century, western diets have become increasingly conducive to developing colon cancer and other malignant conditions in our GI tract. Foods high in saturated fats, sugar, and processed meats are the biggest known culprits of colon cancer in our diets.   Because cancer-causing foods have become so prevalent in many Americans’ diets–this link between nutrition and GI tract cancer may be partially responsible for the staggering rate of increase in young adults developing these conditions. Diagnoses of advanced stage colorectal cancer in people under 55 years of age grew from 11% in 1995 to 20% in 2019, which means one in five people under 55 will have this diagnosis. 

Standard nutritional advice often puts red meat in the same category as processed meat as a colon cancer risk factor, but of course I draw a distinction between grassfed or pastured-raised meats and conventionally-raised beef and lamb, which is used in the research comparing diets including red meat, especially if it’s done in the US. And in fact, in the World Health Organization paper that examined 800 studies to determine the likely carcinogens in our diets (and the nearly 500 page monograph based on it) determined that while the risk was elevated for both processed and red meat, they could not rule out chance, bias, or confounding variables because no association was found between colorectal cancer and red meat in several of the larger studies. Furthermore, they also found that cancer risk was likely mediated by cooking methods, such as pan frying, which was associated with an increased risk of colorectal cancer in one of the larger studies. 

You may have heard of TMAO or trimethylamine N-oxide as something that’s found in red meat (meaning beef, pork and lamb) as well as eggs and dairy products that contributes to colon cancer. What you may not have heard is that salt-water fish and shellfish also are very high in TMAO but are supposed to be good for us. So what gives? What actually is in red meat, eggs, and dairy are l-carnitine, choline, betaine and lecithin, the precursors to a substance called trimethylamine or TMA. Your microbiome converts these precursors into TMA, which is then taken up by the liver and converted to TMAO, which increases colorectal cancer cell proliferation and angiogenesis, or the development of new blood vessels which feed cancer cells. And TMAO has also been associated with other inflammatory conditions, including heart disease, chronic kidney disease, liver disease and type 2 diabetes. 

And because TMAO is produced from substances in meat like l-carnitine, which is an amino acid that’s particularly high in beef and lamb, people who eat vegetarian or vegan diets don’t have the microbes that take part in this conversion, so will produce less TMAO in response to eating the same foods as omnivores. A 2014 study found a positive correlation between colorectal cancer risk and higher TMAO levels. But before you jump to the conclusion that one should avoid red meats entirely, I have to warn you that I see many clients on vegan or vegetarian diets or who eat exclusively fish and poultry who are either having trouble losing weight or suffering from fatigue. I run an Organic Acids Test on them and lo and behold, they have elevated markers that indicate that they are not bringing fats in their diets into the Krebs cycle to produce energy. The reason is usually because they are deficient in l-carnitine (which in addition to being found primarily in red meats is also made by the body from the essential amino acids lysine and methionine). They may also be deficient in vitamin B2, which along with l-carnitine is necessary to bring fats into the Krebs cycle for the production of energy. So when you have a deficiency in one of these nutrients, this means is that after the carbs and protein from a given meal run out, you have no way to use up your stores of fat for energy, resulting in fatigue and fat accumulation. And so what I do for those people teach them about supplements that will help restore the proper functioning of the beta oxidation or metabolism of fats: l-carnitine and a B complex, and when they use those, the fatigue turns around quite quickly. So the message here may be that the poison is in the dose when it comes to red meat.  

And to return to seafood, unlike red meat that just contains TMAO precursors, seafood actually is one of the highest sources of free TMAO as well as TMAO precursors. TMAO is what helps fish stay buoyant by acting like antifreeze and protecting proteins in their tissues–hence, deep-sea fish and shellfish are higher in TMAO. And that fishy smell from seafood is the smell of the conversion of TMAO into TMA. One study found that TMAO levels in the blood were significantly higher following consumption of seafood versus beef or eggs, 62 times higher in fact. Given how healthy seafood has been shown to be, it’s not totally clear whether TMAO is a sign of inflammatory conditions or the result of it. 

And to add some complexity to the story, all this is mediated by the microbiome, so high producers of TMAO have a higher ratio of Firmicutes to Bacteroidetes, typically 2:1 versus 1:1 for low producers. In addition, the high TMAO producers often had no archaea, which you may be familiar with as the kingdom which includes methane producing bacteria like Methanobrevibacter smithii and Methanosphaera stadtmanae, which are overgrown in IMO or intestinal methanogen overgrowth, which causes bloating and constipation. So these archaea actually convert TMA and TMAO into methane, decreasing TMAO in the gut. Unfortunately, I’m one of these people who have no archaea in my gut. But the exciting news is that some scientists are proposing archaeabiotics as a new type of probiotic to help reduce TMAO levels, which means that someone out there is likely working on this as their newest money-making venture. 

As I’ve observed when working with clients who have IMO or methanogen overgrowth, inevitably, diets rich in complex carbohydrates like beans and lentils and starchy vegetables (like vegan diets) increase archaea, whereas Methanobrevibacter abundance is negatively associated with recent fat consumption. And this isn’t because methanogens eat the carbs, as they don’t have the enzymes to do so, but rather that they eat the byproducts of carb consumption of other bacteria like Bifidobacteria bifidum, which has been shown to work with M smithii to produce methane from glucose. And it appears that people whose guts contain more methanogens also contain more Bifidobacteria, which are associated with a host of health benefits, including inhibiting pathogens, producing vitamins, regulating the immune system, repressing carcinogenic activity of other microbes, improving gut barrier function, improving glucose tolerance, reducing low-grade inflammation, and reducing endotoxemia resulting from high fat diets, as well as increasing longevity. Bifidobacteria also are helpful in reducing gas because they produce lactic acid, not gas, so higher Bifido levels lead to less gas and digestive issues. 

All this is to say that the microbiome is an important mediator of TMAO levels, and one of the best things you can do to make sure that your microbiome is rich in the archaea and bacteria that decrease TMAO is to eat a variety of complex carbohydrates and foods high in resistant starch, like starchy vegetables (and by that I don’t just mean potatoes, but sweet potatoes, root veggies and winter squash), and then resistant starch powerhouses like beans and lentils, as well as whole grains like brown rice, quinoa, millet, sorghum and buckwheat. It appears that the combination of resistant starch and other dietary complex carbs (as opposed to resistant starch supplementation alone) is important for getting fiber down to the distal colon or end of the colon where they promote the production of short-chain fatty acids like butyrate, which is protective against cancer. 

I should also mention that there are other substances in red meat and in cooking methods frequently used with meats that are connected with cancer development. This includes N-nitroso compounds (NOCs), whose effects can be mediated by eating green vegetables with your meat, heterocyclic amines from the char on red meats, which according to studies can be mediated by marinating and spicing up your meats with a variety of substances including turmeric, rosemary, Caribbean spice blends, honey, olive oil, lemon juice and garlic marinade, red wine marinade, as well as eating cruciferous vegetables along with your meat. So those are some dietary interventions for being able to eat your red meat in a safe way, but let me get back to conventional prevention methods for colorectal cancer.  

Along with diet changes, changes in your lifestyle that reduce stress have been correlated with reducing intestinal inflammation and lowered risk of developing colorectal cancer. These include meditation, yoga and/or regular exercise, spending time outside to take in Vitamin D, reducing electronic usage before bed, and getting adequate sleep, which is 7-9 hours a night for adults.

Supplements that are helpful in preventing and treating colon cancer include vitamin D3 combined with K2 (I like the Adapt Naturals one as it has the mk4 form of K2), curcumin (I like Curapro, available in my Fullscript Dispensary), resveratrol and quercetin. For the vitamin D, you want to get your levels to the 50-80 ng/mL level, which usually means taking 3000-5000 IU/day of D3. And I prefer the K2mk4 form of K2, which is the only form of K2 that our bodies produce endogenously (although the mk7 form is produced by our gut microbiome). 

And finally, I should mention that there is a marker on the GI Map Stool Test that can identify a risk for colon cancer, called beta glucuronidase, and when found, there are dietary and supplement interventions I can recommend to reduce it. Plus doing a functional medicine stool test to rule out and address any gut infections and correct a state of dysbiosis will reduce your risk of cancerous growths. 

When Should I Get a Colonoscopy?

Because of the high prevalence of colon cancer in the U.S., in tandem with the increasing rate of individuals developing colon cancer at a young age, many health practitioners are now recommending endoscopic colon screenings (also known as colonoscopies) at the age of 45. From that point forward, patients who do not have any polyps or abnormalities developing in their colon are advised to get follow-up colonoscopies every ten years. 

For individuals with risk factors that contribute to their likelihood of developing colon cancer, many healthcare professionals suggest screenings far earlier than they are typically done, as an extra preventative measure. Many risk factors are associated with genetics and hereditary traits, which ought to be considered on an individual basis when deciding whether to seek out a colon screening before the age of 45. These risk factors include an individual’s family history of colon cancer, inherited syndromes like Peutz-Jeghers Syndrome or polyposis, or even one’s racial or ethnic background, as people with African or Ashkenazi Jewish heritage are at an increased risk of developing colon cancer.

Other risk factors for colon cancer include Inflammatory Bowel Disease (or IBD), Type 2 Diabetes, and other diseases with implications on gastrointestinal health. Studies have also highlighted the connection between insulin resistance in diabetic patients and the onset of colon polyps, whereby insulin-resistant cells in the colon begin the process of carcinogenesis, consequently leading to full-blown colon cancer if left untreated. Some lifestyle factors that put individuals at a high colorectal cancer risk include over-eating/obesity, smoking and heavy alcohol use. Smoking in particular has been noted as a significant risk factor for colon cancer, as the chemicals found in cigarettes are known to release free radicals and spurn on DNA damage, creating cell damage and mutations, which can lead to polyp overgrowth.

The reality of colorectal cancer is that many people in the early stages of the disease will be asymptomatic. So it is all the more essential that you get a preventative colonoscopy or endoscopy even before symptoms arise if you’ve hit 45 or earlier if you have risk factors, but even more important if you are having symptoms and have never had these procedures. 

What are colonoscopies and endoscopies?

The general procedure for testing for colon cancer and other GI tract conditions are generally known as endoscopies because they are done with an endoscope, which is a thin, flexible tube with a light and a camera at its tip to look inside the body. If you’re looking at the esophagus, stomach and duodenum, or the first part of the small intestine, it’s called an upper endoscopy or esophagogastroduodenoscopy or EGD. If you’re looking at the colon, it’s called a colonoscopy.  Endoscopic procedures map out a certain area of the gastrointestinal tract using an endoscope inserted through the mouth for an EGD, or through the rectum for a colonoscopy. Endoscopies can surveil your entire GI tract, looking for abnormalities anywhere from the esophagus down to the rectum. The endoscope allows doctors to capture real-time images of the internal structures on a video monitor. 

Before a colonoscopy, your doctor will have you consume a bowel prep kit to completely empty your bowels the day beforehand. These will include osmotic laxatives and electrolyes to keep you from getting dehydrated. 

For low-risk individuals, rather than jumping straight to colonoscopies, there is the Cologuard option, which is a much less invasive stool DNA test for colon cancer. It’s not advised for high-risk individuals, including people who have IBD or a family history of colorectal cancer. And according to GI Alliance, Cologuard can miss up to 8% of colon cancer and more than 50% of pre-cancerous polyps, so you need to take that into account.  I chose to do a Cologuard instead of a colonoscopy when I turned 50 but decided I’ll go ahead with a colonoscopy soon now that it’s been 3 years, the interval for repeating Cologuard, just to be safe, since I since learned one of my parents had had a polyp found on a colonoscopy. 

Upper endoscopies or EGDs look for cancerous and precancerous growths in the esophagus, which is called Barrett’s esophagus in the esophagus, and in the stomach or upper intestines. They also look for gastritis or inflammation of the lining of the stomach, ulcers, narrowing of the esophagus, blockages, and can include biopsies for celiac disease and H pylori. An upper endoscopy can help to find the causes for heartburn, trouble swallowing, excessive burping, bleeding, nausea and vomiting, pain and unexplained weight loss. 

What diets do functional medicine practitioners recommend for colon cancer? 

Functional medicine approaches colon cancer from a holistic perspective, aiming to address the root causes of the disease and the terrain, which is like thinking about the soil rather than the individual plant, rather than solely focusing on killing cancer cells and symptom management. 

Three possible dietary changes that functional medicine practitioners may recommend to those with early-stage colorectal cancer (in addition to treatments like chemotherapy, immunotherapy, or surgery, that address the cancer directly) are low-carb diets, anti-inflammatory diets and ketogenic diets. Anti-inflammatory diets aim to limit foods that induce chronic inflammation in the intestines, thus lowering your risk of developing malignant growths and mutant cells in your intestinal lining. This involves eliminating refined sugar, refined oils, gluten, processed meat, among many other foods (that tend to be high in saturated and trans fats). Alternatively, these diets promote fruits and vegetables, fermented foods, grass-fed animal products and healthy fats, like those found in olives and avocados. 

Low-carb diets would eliminate many of the same foods and can go hand in hand with anti-inflammatory diets, with the extra restriction of only having 35-50 grams of carbohydrates a day. 

Along similar lines, ketogenic diets promote a very low-carbohydrate diet that forces the body into the process of ketosis, in which the body acclimates to burning fat as a primary source of energy as opposed to readily available carbohydrates. A 2017 systematic review of ketogenic diets in animal models found that in nine of 13 studies that were eligible for inclusion a ketogenic diet inhibited malignant cell growth and increased survival time. This review included colon cancer and gastric cancers as well as 5 other types of cancer. However, there is no data yet on humans. This is likely mediated by the fact that ketogenic diets produce ketone bodies like beta-hydroxybutyrate, which can substitute for butyrate produced by the microbiome when it ferments carbohydrates, which is protective against colon cancer.

If you do choose a ketogenic diet, you should do it carefully with the help of an experienced ketogenic diet coach or other practitioner as there are many potential adverse side effects and some people just do not tolerate super high levels of fat in their diet, which is required on a ketogenic diet in the range of 70% of calories. 

A well-studied alternative to ketogenic dieting is intermittent fasting, which has been identified as a good counterpart to those undergoing chemotherapy for colorectal cancer. Cycles with short periods of fasting have been found to reduce malignant tumor growth. Typically, functional medicine practitioners will advise that you align your fasting period with your sleep schedule, in which case, you may fast from after dinner through to breakfast or lunch the following day, and this may be scheduled in particular in advance of chemo treatments and will reduce the damage that the chemicals given to you have on your own cells. Based on an individual’s ability to tolerate periods of fasting in their daily routine, they can certainly fine-tune their fasting schedule to assure that they aren’t compromising their health or their ability to work, exercise, and otherwise feel sufficiently fueled throughout the day. These partial fasting methods may involve working caloric drinks into your fasting periods to tide you over and limit sensations of fatigue. If you’re dealing with cancer, I’d recommend listening to my episode 26 with Nasha Winters from July 30, 2020. We get into fasting schedules and interacting with chemo on that episode. 

I wanted to mention colonoscopies and endoscopies as an important step for people with new and persistent gut and bowel issues, so if you haven’t yet seen a gastroenterologist, I’d recommend making an appointment and going through that process before seeking out functional medicine interventions. 

If you’re struggling with  bloating, constipation, diarrhea, soft stool, acid reflux, IBS, IBD or any type of chronic disease, etc. and want to get to the bottom of it, that’s what I help my clients with. You’re welcome to set up a free, 30-minute breakthrough session with me (Lindsey). We’ll talk about what you’ve been going through and I’ll tell you about my 3- and 5- appointment health coaching programs in which I recommend lab tests, educate you on what the results mean and the protocols used by doctors to fix the problems revealed. Or if you’re ready to jump in right away or can just afford one appointment at a time, you can set up an 1-hour consultation with me. 

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