Dear Mark: Thank You! (Resistant Starch Doesn’t Actually Cause Colon Cancer)

Easily the subject of most emails, tweets, FB messages and comments directed at me over the last week or so has been about this recent study: Gut microbial metabolism drives transformation of msh2-deficient colon epithelial cells.

I glanced at it and my immediate sense was: “unbridled reductionism.” I don’t see much utility in reducing things to isolation, disregarding other factors. In this case, it’s important to consider all the benefits and downsides to resistant starch and then weigh them to get an overall view. In other words, the only way this study has relevance in my view is for people whose #1 goal in life is to prevent colon cancer at all cost or discomfort.

Anyway, given my recent moving activities I was unable to spend any time on it. Them commenter Gemma said this of the study and I kinda just nodded and put it out of my mind:

As usual, the circumstances and the concentration matter. It is rather complex. My take.

Read the study cited in the study you linked:

The Warburg Effect Dictates the Mechanism of Butyrate-Mediated Histone Acetylation and Cell Proliferation

We are speaking tumour cells, not healthy cells.

Butyrate concentration differs in proximal / distant colon, and it’s significantly lower deep in the crypts, where the neoplasmatic cells are formed. TOO LITTLE butyrate does not inhibit proliferation of a tumour cell, it is rather used up as fuel. Increase butyrate, and the proliferation is inhibited. Especially increase butyrate content at the distal part of the colon, where most of the colorectal cancer starts. (No, it won’t happen by eating more butter).

Haven’t you already heard it here?

In other words, if there is already a tumour cell at the bottom of the crypt and there is too little butyrate reaching it, there is no inhibition.

“Butyrate is an attractive candidate for chemotherapy or chemoprevention because it selectively inhibits tumor growth and has minimal adverse effects in clinical trials (Pouillart, 1998). However, the efficacy of butyrate as a chemotherapeutic agent has been limited by its rapid uptake and metabolism by normal cells (resulting in a half-life of 6 min and peak blood levels below 0.05 mM [Miller et al., 1987]) before reaching tumors (Pouillart, 1998). More stable butyrate derivatives such as tributyrin have also not been successful on a consistent basis (Pouillart, 1998). A fiber-rich diet might be more successful for chemoprevention because it delivers mM levels of butyrate (via the microbiota) to the correct place (the colon) before the onset or at an early stage of tumorigenesis. Evidence for this idea comes from recent human studies demonstrating lower levels of butyrate-producing bacteria among the gut microbiota of colorectal cancer patients compared to healthy participants (Balamurugan et al., 2008; Wang et al., 2012), and studies showing an inverse correlation between fecal butyrate levels and tumor size in colorectal cancer (Boutron-Ruault et al., 2005; Monleón et al., 2009).”

And now today, Mark Sisson delves deep into the matter: Dear Mark: Does Resistant Starch Cause Colon Cancer?

From my reading of the research, resistant starch (and the resultant butyrate) has an overall beneficial, preventive effect on colon cancer risk. That relationship may change or become more complicated in advanced colon cancer, and the story may be entirely different for people carrying the MSH2 mutation from today’s highlighted study, but that remains to be seen. For now, I’m still incorporating RS into my diet.

If you’re worried, ask your doctor about getting an MSH2 status test. And review your family history of cancer. Was it colon? Was it a DNA repair mismatch-related case? Even if you do have the MSH2 mutation and a family history of Lynch Syndrome, don’t fear fermentable fibers, resistant starches, and butyrate. Your colonic cells run on butyrate. It’s their primary energy source. And all the other myriad benefits of prebiotics remain relevant. Besides, this is one study. It’s not proof or confirmation of anything. Not yet.

Alright, water’s safe. Everyone can get back in the pool, now.

Note: I’m currently drafting a ginormous post revisiting an old friend: The Incredible, Edible Tigernut. For publication later this month.

Since Covid killed my Cabo San Lucas vacation-rental business in 2021, this is my day job. I can't do it without you. Memberships are $10 monthly, $20 quarterly, or $65 annually. Two premium coffees per month. Every membership helps finance this work I do, and if you like what I do, please chip in. No grandiose pitches.


  1. gabkad on August 4, 2014 at 15:32

    Interesting in that I was thinking other things may factor into resistance to developing colon cancer. Like deficiencies in minerals or vitamins. But then I thought, there’s all these people eating resistant starch and crapping all over the place who have suboptimal nutrition for sure. They die of other things.

    Eat your damn beans and don’t fart in the pool.

    Thanks in advance.

  2. Eduardo Bernardo on August 6, 2014 at 19:23

    I’ve been away, so sorry if this has been seen before, but bumped into it today… Cold potatoes could counter health effects of red meat

    +1 for RS
    -1 for brainless red meat scare echo chamber

    some scientists

  3. Brad Baker on August 6, 2014 at 19:26

    Rich, that Eduardo Bernardo guy is me. Somehow I logged in with an alias that I created for posting nasties – on other blogs of course ;-) Maybe it was Woo’s. cheers, -Brad-

    • Frank Enstein (@SkyKing1717) on August 9, 2014 at 20:15

      Beans? Tubers? Really? According to this slideshow presentation by a Doctoral Candidate at Tel Aviv University, perhaps you should hold your starch!

      Since when did carbohydrates, in the way of beans and tubers, become an essential nutrient?

    • Richard Nikoley on August 10, 2014 at 08:05

      “Beans? Tubers? Really?”

      Yep, really. I like and respect Miki a lot and he’s followed my blog off and on for years. But I’ll take the anecdotes of myself, family, and the hundreds or even thousands posted in comments here over Miki’s slide presentation. With all respect, of course.

    • Richard Nikoley on August 10, 2014 at 08:06

      All Blue Zone peoples consume legumes. Every one.

    • Frank Enstein (@SkyKing1717) on August 11, 2014 at 20:18

      Well, as you very well know….correlation does not imply causation. There are other factors/ lifestyle characteristics that in combination, besides eating legumes, could be contributing to the longevity of those living in the Blue Zone, such as:
      1. Family – put ahead of other concerns.
      2. Less smoking.
      3. Constant moderate physical activity.
      4. Social engagement – people of all ages are socially active and integrated into their communities.

    • Richard Nikoley on August 11, 2014 at 21:41

      Frank, you forgot Kool Aid.

    • Frank Enstein (@SkyKing1717) on August 12, 2014 at 16:39

      Not to mention Bob’s Red Mill Potato Starch from Amazon! I wonder if our Paleo ancestors also ordered Bob’s Red Mill Potato Starch from Amazon?! If they did, then I’m definitely jumping on the RS bandwagon!

      But if they didn’t, then they prolly cooked their taters, then froze ’em in their freezers, then cooked them again cuz that’s been shown to be one of the better ways to get RS!

    • Richard Nikoley on August 12, 2014 at 17:18

      Do whatever you want, Einstein.

  4. Sap on August 8, 2014 at 15:34

    Alright, so I’m very late to the dance on this resistant starch thing, but I wanted to hijack your newest post to say thanks. I’ve been spending the last week reading everything I can on here about the topic (you people put most of the good stuff in the comments!) and I started taking PS daily (mixed with protein powder, chia seeds and a bit of water and cream, quite good really). I’ve got autoimmune/inflammatory issues that were kept in check for a long time with a grain free/low carb diet, but spent the last couple months feeling sick no matter what I ate. So far so good with the starch, biggest change is I’m actually sleeping (was so restless I was getting 3-5 hrs of broken sleep a night), which in itself is a huge improvement. Thanks for all the info.

  5. Jo on August 16, 2014 at 00:09

    When is that book by you, tatertot and DrGB coming out?

  6. Lara on April 9, 2017 at 23:31

    OH MY GOSH! I cannot tell you how happy this makes me. This connects so many dots!!! I’m so excited to read everything you write.?

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