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Fiber to Support a Healthy Immune Response to Cancer Treatment?!

A wooden spoon filled with fiber grains

Dietary fiber is kind of like the Rodney Dangerfield of the lifestyle or nutrition world because it still does not get enough respect. I realize many young folks reading this column are Googling “Who is Rodney Dangerfield?” right at this very moment and then, when they realize what I mean, they are simultaneously thinking “dad joke” in the back of their minds. Yes, I love dad jokes more than artichokes and that is a lot!  Anyhow, I digress.

There is not much money behind plain old natural dietary fiber, but it has been associated with all kinds of diverse healthy changes, including: less acid reflux, reducing constipation, lowering cholesterol and blood sugar, helping some lose weight and reduce blood pressure, dampening inflammation, and it is even being studied against prostate and other cancers. In fact, there has been a recent suggestion that dietary fiber could also help create compounds in the gut that improve immune surveillance.1 Yet, it was a recent study from MD Anderson Cancer Center that not only caught my eye, but also had me saying “Wow” and “Wow” spelled backwards!2 How did I miss this study at the end of 2021 and beginning of 2022?! This study suggests a potential new way fiber may be utilized in some future cancer treatments. Now, here comes the disclaimer, folks. This is preliminary observational data in the cancer research world, and it came from a study of primarily metastatic melanoma patients also receiving conventional immunotherapy, but it was still fascinating! And, of course, I like fascinating! Plus, I just like the word “fascinating” because the word itself is so fascinating.

Researchers found, of the 128 patients on immune therapy (immune checkpoint blockade or ICB) for cancer treatment that, in general, greater clinical benefits from their conventional immunotherapy cancer treatment was found for those patients with higher fiber intake, which was 20 grams or more per day, mainly from vegetables, fruit, beans, and whole grains (that is not that much – a little above average). Higher dietary fiber could impact the gut microbiome and increase the response to immune therapy medications?! Again, this is preliminary, but the other heart healthy benefits of consuming more fiber are reason enough to think about getting more of this stuff in your diet. Still, these researchers were brilliant because they also conducted a laboratory experiment to support their findings and it did just that! Fiber intake was associated with immune or microbiome benefits. Interestingly, no such overt benefit was found in this same study for patients utilizing healthy bacteria products (aka probiotics). 

So, is it possible that by increasing dietary fiber we can all increase our overall immune health? Maybe, but as prostate cancer and other tumor types continue to have some forms of immune therapy utilized in treatment, it would be interesting to determine if fiber could improve the response to different forms of immune therapy drugs or even other forms of treatment. What is there to lose, except a few pounds, or a few cholesterol or blood sugar points?! In other words, dietary fiber is again one of the foundations of a good overall diet and it is heart healthy, so I think health care professionals should discuss these interesting studies with their patients.

Oh, and by the way – another recent study from New Zealand found a potentially better response to the flu vaccine in a group of folks with higher dietary fiber intakes, which was also supported by a laboratory study conducted by the same group.3 Again, this is all just preliminary, but it is fascinating! Yes, fascinating! I am fascinated over simple dietary changes to improve the response to conventional treatment. So, the next time you have an artichoke, avocado, kidney beans, or even a peach, your immune system might say “thank you,” and also “fascinating!”

  1. Westheim AJF, et al. Front Nutr 2022; doi: 10.3389/fnut.2022.868436.
  2. Spencer CN, et al. Science 2021; 374: 1632-1640.
  3. 3. Cait A, et al. Front Immunol doi: 10.3389/fimmu.2021.765528.