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It’s no secret that what scares those of us diagnosed with IBD most, is the increased cancer risk.

If this is news to you, then I’m sorry, but it’s true.

Let’s look at some of the numbers:

In an article written by Crohn’s & Colitis UK, a study is referenced that found that for those with much or all of their large bowel affected-

  • 1 in 100 may develop bowel cancer at 10 years
  • 2 in 100 may develop bowel cancer at 20 years
  • 5 in 100 may develop bowel cancer after 20 years

This review in the World Journal of Gastroenterology paints a more sinister landscape, quoting that the likelihood of developing colorectal cancer (CRC) is-

  • 2% after 10 years
  • 8% after 20 years
  • 18% after 30 years

Whichever we choose to pay attention to (and there are others), however, we must acknowledge that longstanding inflammation is a bad thing.

Interestingly, the same review review published in the World Journal of Gastroenterology states that long term use of immunosuppressive drugs can also promote carcinogenesis (cancer development).

So what can we do to reduce our cancer risk having been diagnosed with IBD?

The good news is that there are a number of things we can do, and this list is by no means exhaustive.

Have a handful of nuts every day

First, let me say that if you are at the beginning of your healing journey, then nuts are a bad idea. They are high in insoluble fiber which reduces intestinal transit time and can increase diarrhea-like symptoms. They are also too scratchy for an inflamed gut.

If, however, you are in remission, adding a handful of nuts occasionally could be a good idea. Everybody is different though and IBD is nuanced, so do what’s right for your body. If nuts are simply a no-no for you, then don’t eat them 🙂


This 2018 study published in the Nutrition Journal found a very strong correlation between increased nut consumption and reduced CRC risk.

This 2018 study published by a team of researchers at Yale University found that Stage III colon cancer patients who ate 2 or more servings of nuts per week had a significantly reduced risk of CRC recurrence and death.

A secondary analysis of the latter study revealed that reduction in CRC risk appeared to be limited to tree nuts, with peanuts and peanut butter showing no association with reduced CRC risk. Given the incredibly widespread consumption of peanuts and peanut butter, this is an important finding. Plus, peanuts are actually legumes, not nuts…

The nuts that I would recommend are walnuts, pecans, pistachios, and macadamia nuts and they should be eaten raw to avoid oxidation of the polyunsaturated healthy fats that they contain. Also, they can (and should?) be soaked if you have trouble tolerating nuts. If you are one of the lucky IBD’ers who can tolerate nuts, then I would recommend adding up to 3 handfuls of nuts per week.

Consume a low sugar diet

If you haven’t been living under a rock for the last 10 years, you’ll have witnessed the ‘Sugar is Evil’ movement. Ok so I made that tagline up, but it’s pretty much what’s being spread around.

This study published in the Journal of the European Society for Medical Oncology shows that increased glycemic load, that is, increased consumption of foods that raise blood sugar, is linked to increased risk of certain cancer types including CRC.

And this study published in the Journal of the National Cancer Institute found that increased glycemic load was associated with increased risk of recurrence and mortality in Stage III colon cancer patients.

This study published in the American Journal of Clinical Nutrition showed a significant increase in inflammatory markers in even low to moderate consumption of sugar sweetened beverages. And this study published in Lipids in Health and Disease also showed dietary sugars increasing inflammatory markers.

Looking past studies that link sugar with cancer directly, we can see there is a wealth of evidence linking sugar with what is becoming widely accepted as one of the main causes / precursor’s to cancer – inflammation.

One of the preeminent mechanisms by which dietary sugar consumption leads to inflammation is by free fatty acid formation in the liver, producing metabolites which trigger inflammatory processes.

This review of sugar-sweetened beverage (SSB) intake in relation to biomarkers of chronic disease, including inflammation, showed that increased consumption of SSBs lead to lower HDL (‘good’ cholesterol) and higher CRP (a marker of inflammation). The review was based on data taken from the National Health and Nutrition Examination Survey from 1999 to 2010.

Also, some of the existing evidence of sugar consumption leading to increased CRC risk seems to be related to sugar’s effect on insulin. The exact mechanism behind high insulin levels increasing cancer risk may be due to the increase in available IGF-1 it’s role in stimulating cell growth.

I recommend eliminating everything with added sugar (especially high fructose corn syrup), except for the occasional treat. If you have a sweet tooth, you can combat cravings by incorporating naturally sweet, low glycemic foods such as sweet potatoes, carrots, and berries including strawberries, blueberries, blackberries and raspberries.

Enjoy fermented dairy products

I’m incredibly interested in this topic as I’m a big proponent of fermented foods, especially kefir. In fact, I try to consume some form of fermented foods every day. But is there any evidence to support the claim that consuming fermented dairy products can decrease your cancer risk? You bet there is.

This meta-analysis of 61 studies including 1,962,774 participants and 38,358 cancer cases found that fermented dairy consumption was associated with a significant decrease in colorectal cancer risk.

This 2014 study in the International Journal of Oncology finds that kefir is both anti-proliferative (that is, it stops cancer cells from multiplying) and also able to induce cell death in colon cancer cells.

There are others, I welcome your own research.

Note that almost all dairy available to us in supermarkets these days is pro-inflammatory (containing A1 beta casein – long story) and generally not the dairy that I recommend to my clients.

I recommend fermented dairy products (kefir and cheeses) made from raw, A2, grass-fed & organic milk. That’s quite a bunch of tick boxes, but it’s out there. If you’ve no idea where to start looking, here’s a raw milk finder to begin with: https://www.realmilk.com/real-milk-finder/.

Another note – dairy is not well tolerated by everyone and consuming raw milk carries risks – as such, this is not a blanket recommendation to go out and purchase raw milk. As with everything related to your health, the onus is on YOU to make the best decision for YOU.

Consume a high fiber diet

If you’ve been diagnosed with IBD, you may have been told that fiber is not a good idea. In fact, you may be terrified of consuming foods high in fiber. I know how that feels, because I was too.

But these days, in my coaching practice, fiber is one of the first tools in in toolbox that my clients and I will use as a means of fighting inflammation. Of course, there are times when a low fiber / low residue diet will make sense for some people, especially in the early stages of healing from IBD, but the number of people that respond positively to a high fiber diet by far outweighs the number of people that do not.

But don’t take my word for it-

This 2015 study published in The American Journal of Clinical Nutrition sought to assess the relationship between dietary fiber and the incidence of colorectal cancer. 50,000+ participants enrolled in the study. The researchers found that those with an elevated dietary fiber intake had a significantly lower chance of developing CRC.

The Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial (referenced in this Harvard article), started in 1993 and evaluated 33,971 volunteers over 7 years. Researchers found that 10% or more developed adenomas (benign tumors that precede almost all colon cancers), but that those who consumed the most dietary fiber had a 27% lower chance of developing adenomas than those who consumed the least. This is significant.

If you’re wondering what the best sources of dietary fiber are, then as well as the usual suspects like dark leafy greens / cruciferous vegetables, I’d encourage you to go for options that are able to feed the butyrate producing bacteria in your gut. That’s a whole topic in itself and you can read an article I wrote here that will break it down for you.


We’ve all been told (and intuitively know) that exercise is good for us. And it’s good for so many things from mood, to appearance, to improving sleep, to prevention of neurodegenerative diseases, cardiovascular diseases, and cancer.

This 2019 review published in the World Journal of Gastrointestinal Oncology discussed the beneficial effects of exercise and in both the treatment and prevention of CRC and also the proposed mechanisms at play. In fact, it states that physical activity may prevent up to 15% of all colon cancers. That’s huge, folks.

The mechanisms at play seem to be related to exercises effect on

  • Inflammation
  • Insulin
  • Immunity
  • The microbiome

There have been challenges working out just how much exercise is necessary to protect against CRC, however the literature seems to suggest that intense exercise is most effective in protection against CRC, with the optimal frequency being somewhere in the region of 3-4 hours per week.

I’m not suggesting, by the way, that you go and kill yourself in the gym right now. Because frankly, for those of us suffering from chronic illness, that is often not a good idea. You need to do things at the right pace for your own body and current state of physical health & ability.

Also, intense physical exercise has been shown to induce cases of ischemic colitis (eg a marathon runner experiencing diarrhea).

So be smart. Should you look to incorporate some intense physical exercise on a weekly basis? Probably. Should you do that within the confines of what your own body can tolerate? Definitely.

Manage stress

As I started to research this topic, I was actually surprised at how few studies there are linking stress to increased CRC incidence.

I’m not saying that they don’t exist – however – and here’s one of them=-

This 2017 study published in Scientific Reports following 61,000+ Japanese men and women showed a significant increase in risk of rectal cancer with increased levels of perceived stress (though interestingly there was no significant increase in risk of colon cancer).

However generally the science is pretty mixed, with some studies showing perceived stress as a strong indicator of CRC incidence and other studies finding no association. This may be because this is a very challenging topic to study, due to the subjective nature of perceived stress.

What is undeniable, though, is that stress (especially chronic stress) leads to inflammation, and inflammation is a strong predicator of cancer incidence.

So do what you can to manage your stress people – it’s a vital part of being healthy.

Summary & A Word Of Caution

There are a number of things that you can do to reduce your risk of colorectal cancer if you have ulcerative colitis or Crohn’s disease. And by taking action in several areas, it’s possible that your net risk of CRC could be reduced even with the increased risk from IBD.

But I am not suggesting that you take things exclusively into your own hands. Listen to your doctor, go for check-ups, and don’t ignore the signs.

Stay strong, friends.

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