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.