March is Colon Cancer Awareness Month

You may or may not already know that March is Colon Cancer Awareness Month. 

I felt motivated to write on this topic in part because my late grandfather had colon cancer, and in part thanks to a well known gastroenterologist in the US called Dr. Will Bulsiewicz @theguthealthmd I follow on Instagram who talks at length on this subject. Just by the way, he also has a fantastic and very inspiring book called ‘Fiber Fueled’ that is well worth a read.

Sadly colon cancer (also more generally referred to in the UK as bowel cancer) is not rare and it’s also currently the second most deadly cancer. The small silver lining is that not all countries struggle with colon cancer the way that the Western world does… It therefore follows (and there’s a growing evidence indicating) that the high incidence is directly attributable to dietary habits in the Western world. And it’s not just colon cancer that is linked to diet. According to the World Health Organisation (WHO), research suggests that as much as 30% of all cancer cases are linked to poor dietary habits, and are therefore preventable. 

In fact, eating the right foods, in the right amounts and maintaining a healthy weight throughout life may be one of the most important ways we can protect ourselves against cancer. It is potentially the second most important factor, after avoiding tobacco use. And here’s another eye-opening statistic for you - approximately 10% of colorectal cancers are due to genetic causes but about 90% can be attributed to environmental factors, particularly diet*.

And yet, unfortunately merely changing our diet does not adequately reduce our risk… but as Dr. Will says, thankfully there are some key means by which we can reduce our risk of cancer, and especially of the colon:

ELIMINATE RED AND PROCESSED MEAT FROM OUR DIET

Red and processed meats (eg. meat that has been preserved by curing, salting, smoking, drying or canning such as sausages, hot dogs, salami) have consistently been linked to increased risk of colon cancer. 

Not to get too technical but there are actually a number of damaging mechanisms that come into play here:

• Polycyclic aromatic hydrocarbons (PAHs) are formed when fat / juices from meat grilled directly over a heated surface or BBQ drip onto the surface or fire, causing flames and smoke that then adhere to the meat. These PAHs generate carcinogenic and mutagenic effects.

• Nitrosamines and heterocyclic amines present in cured meats, especially bacon, are strong carcinogens that may produce cancer in organs and tissues

• Heme iron (iron from animal sources) can cause oxidative stress and DNA damage. Because DNA provides the blueprint for the proteins our cells need to function, this damage can cause serious issues, including cancer.

• High saturated fat in the diet shifting the gut microbiome to produce more secondary bile acids (BAs), which, at high concentrations can act as strong stimulators of colon cancer formation (PMID: 30430113).

So, seeing this, it’s not difficult to see why, after a complete review of the available evidence (over 800 studies) the World Health Organisation’s International Agency for Research on Cancer labelled processed meat as carcinogenic to humans and red meat as probably carcinogenic to humans.

PLANTS ARE THE WAY FORWARD

In a nutshell, vegetarian diets are associated with an overall lower incidence of colorectal cancers (PMID: 25751512).

Plants genuinely have it all - protein, carbs, healthy fats, water, vitamins, minerals, antioxidant polyphenols, phytochemicals (compounds found in plants that can help prevent chronic diseases like cancer), and of course, fibre. Collectively these can significantly contribute to protection from cancer! 

For example, both calcium and magnesium have been linked to a reduced risk. Plus, phytochemicals that can provide protective effects include curcumin (from turmeric), catechin compounds in green tea, resveratrol in red grapes, and sulforaphane in cruciferous (green leafy) vegetables. 

The list of cancer-fighting foods is usually topped with berries, broccoli, tomatoes, walnuts, grapes and other vegetables, fruits and nuts, but pretty much all plant foods contain phytochemicals so we don’t actually need to focus on a specific list of "cancer-fighting" foods to the exclusion of other healthy foods. Incredibly, there are more than 4,000 phytochemicals that have been discovered and researched to date, however, there's not any one ‘superfood’ that contains all of them and they all offer different functions and benefits.

With this is mind, variety truly is the spice of life and a great way to add variety to our diet is to make sure we include a full spectrum of naturally colourful foods. Yes, we literally need to “eat the rainbow”. Ultimately, we can get the most comprehensive protection by eating a wide variety of plant foods.

FUEL UP ON FIBRE!!!

This is so easy but yet so crucial and it’s almost as if the world is recently waking up to the idea that we NEED fibre to function.

Dietary fibre (AKA roughage) is the indigestible part of plant foods and it offers an array of health benefits, including reducing the risk of heart disease, better gut health, weight management, balanced blood glucose and a reduced risk of type 2 diabetes.

Fibre is found in highest doses in vegetables, fruits, whole grains, and legumes. There are two types — soluble and insoluble — and both play vital roles in our health:

• Insoluble fibre does not dissolve in water and adds bulk to the stool, preventing constipation

• Soluble fibre absorbs water, forming a gel-like substance in the digestive system. It may help lower cholesterol levels and regulate blood sugar levels

Thanks to Dr. Will again here -  a systematic review and meta-analysis of 185 prospective studies compiling 135 million person-years of data (let’s bear in mind that the entirety of human existence is just 3 million years), Dr. Andrew Reynolds found that “dietary fibre was significantly associated with reduced risk of developing colorectal cancer”. Further, he found a “dose response relationship”, whereby as fibre intake increases, so too do the benefits. For every 8 grams of fibre, there was an 8% reduction in colon cancer incidence. 

This is totally logical since dietary fibre fuels our gut bacteria. Short chain fatty acids (SCFAs) are produced when the friendly gut bacteria ferment fibre in our colon, and are the main source of energy for the cells lining our colon. For this reason, they play an integral role in colon health. SCFAs are believed to also influence gut-brain communication and brain function directly or indirectly.

And yet, many of us still don’t get the minimal recommendation of 30 grams of fibre a day! It’s time to start eating more raspberries and kidney beans… but maybe not together!!!

4. SCREENING SAVES LIVES

Lastly but by no means least, it’s important to mention that according to the experts, one of the major problems with colon cancer is that symptoms don’t usually manifest until it’s too late for the cancer to be cured. Many of us will know close contacts who have had a pre-cancerous polyp (or two) removed upon having a colonoscopy and this has arguably saved their life. 

The current recommendation in the US is to do colonoscopy once every 10 years beginning at age 45. And yet, in the UK, bowel/colon screening checks are available to everyone aged 60 or over. For individuals who have a first degree relative who developed colon cancer before the age of 45, the lifetime risk for colon cancer is 1 in 10. There is already a consensus that such individuals should be offered screening, five yearly, starting 5–10 years younger than the age at cancer presentation of the relative.  So if you think you might be at-risk or you’re concerned, speak to your doctor and get checked as early as possible. 

On that note, I leave you with plenty of food for thought and hopefully also positivity about the many ways we can reduce our risk - not only colon cancer, but many other cancers too.

*Rhodes J., Colorectal cancer screening in the UK: Joint Position Statement by the British Society of Gastroenterology, the Royal College of Physicians, and the Association of Coloproctology of Great Britain and Ireland Gut 2000; 46:746-748.