Gut vs. Gut: This is how & why Resistant Starch is working.


You may recall in my inaugural post that I took a deeper dive into the American Gut results of Tatertot Tim, the internet’s fiercest promoter of the benefits of Resistant Starch. In particular, I compared his results to Michael Pollan’s gut makeup as a way to postulate some theories about what we know and don’t know — particularly with regard to the optimality of Resistant Starch compared to other fermentable fibers. I concluded the post by saying that it’s all just a little too speculative to say that Pollan’s high firmicutes are a result of eating lots of fermentable plant food, and that just looking at phylum-level results wasn’t going to provide us with anything conclusive. Well, I think I’ve come upon something a little more useful.

Below, you’ll see the gut sequencing results of none other than American Gut founder Jeff Leach himself.


This is significant for a few reasons. First, Jeff is an admitted Paleo-ish eater — very little grain consumption, and moderate-to-high protein & fat. No restriction on other starchy carbs as far as I can tell. And I assume he steers clear of the usual junk (n6 oils, high fructose, etc.). This is quite close to Paul Jaminet’s Perfect Health Diet, a very popular Paleo diet variant. Well it turns out Tatertot, too, is not only Paleo, but a follower of Jaminet’s PHD. So this already makes for a great comparison. With Pollan, there are too many potential confounding factors to account for — a clean, whole foods-eating omnivore, but certainly a lot of grain consumption (with the Prevotella to show for it), and perhaps lower-than-average meat/fat consumption. Just too many unknowns.

But here is where it gets really interesting and makes this a worthwhile comparison: the one significant area where Jeff differs from Tim — and from the vast majority of people — is his obsessive focus on consuming a high and diverse load of fermentable fiber from plant foods that feed gut bacteria. Jeff professes to aim for consuming 20 to 30 species of plants a week, and claims to get up to 100g of fiber per day. He eats onions, garlic, and leeks every day — foods with a high amount of fermentable fructooligosaccharides, including scFOS. If we’re looking for the gut sequencing results of a person committed to bulletproofing his/her gut microbiome, Jeff’s are as close to a gold standard as we’ll get.

So here, again, are Tim’s results:


When we make the comparison between Jeff’s and Tim’s gut results, what do we see? There it is again, firmicutes and bacteroidetes, totally opposite ratios. Tim is all orange. Jeff is all red. Even more lopsided than when compared to Pollan. And what accounts for that? I could tell you, but why don’t I just let Jeff speak for himself. Here’s how he explains his results in a Facebook comment on the American Gut facebook page, after someone questions whether his high firmicute count is a concern because of past studies showing links to obesity:

the “firmi = obesity” doesn’t really hold up anymore. in the human microbiome project – which looked at 250 healthy and normal weight folks – ppl fell along a continuum – some were 80% firmicutes, others were 20%. we see the same thing in american gut. my firmicutes are high due to high levels of members of the family of ruminococcaceae – lots of fiber fermenters in that group.

There you have it. His high firmicutes are a direct result of eating plant foods that stimulate fiber-eating bacteria. From the expert himself. I’ll also add that in addition to Ruminococcaceae, Lachnospiraceae — another plant-chomping Firmicute group — adds to that strong Firmicute count at 11.5% (it’s his third highest group; bacteroidetes is predictably in the #2 slot). So what’s the relevance of high Ruminococcaceae and Lachnospiraceae?

Ruminococcaceae and Lachnospiraceae are synonymous with Clostridium cluster IV and Clostridium cluster XIVa. These are the same immensely important commensal Clostridium clusters I wrote about in my original post. These are the butyrate producers, and have been shown in study after study to be some of the most consequential bacteria for gut health. Cluster XIVa alone accounts for up to 60% of mucosal bacteria in the gut. And we now have proof that when you bulletproof your gut with fermentable fiber, as Jeff Leach has, it is these groups that are doing the bulletproofing. (And just to really drive it home: Michael Pollan has high levels of these groups as well. What else would you expect from Mr. Eat Mostly Plants?).

So there you have it. Tatertot Tim megadoses on Resistant Starch, but doesn’t have a whole lot to show in his firmicutes. Case closed. Resistant Starch, we hardly knew ye….

But we still have a problem. Regardless of Tim’s results, we know that Resistant Starch is working. It’s having all the effects that we expect people to have from consuming gut-feeding, butyrate-boosting fermentable fibers. People are reporting results. Improved metabolic markers, improved digestion, weight loss, better sleep, improvement in IBS symptoms. Results don’t lie. How could that be???

Well, let’s take a look again at that chart comparing fibers from my original post. If you remember, Resistant Starch was somewhere in the middle of the pack, only significantly stimulating a few specific strains:


Tak a look at those two highly stimulated buggers — Eubacterium Rectale and Roseburia intestinalis. Hmm, those sound familiar. OH THAT’S RIGHT. Remember that Cluster XIVa (aka Lachnospiraceae) I just told you about — the one that accounts for almost 60% of mucosal bacteria? You know, bacteria that have “a unique composition and potential to influence human health”? Well Roseburia intestinalis and Eubacterium rectale are the leading colonizers of Cluster XIVa! Roseburia, specifically, governs butyrate production. And that third highly stimulated bugger, R. Inulinivorans? Also in Cluster XIVa. Resistant Starch loves Cluster XIVa.

So here, I’ll make this really easy:

What Resistant starch lacks in breadth, it makes up in precision. Resistant starch is a laser-guided missile aimed at the two most important strains of mucosal bacteria in one of the most crucial clusters of bacteria in the human gut.

Want the proof? Scroll back up to Tim’s results. Check out #4 for his most abundant microbes. Lachnospiraceae, aka Cluster XIVa. A respectable 4.5%…and I’ll just bet R. intestinalis and E. rectale have something to do with it.

(Side note: Yes, Tim’s Ruminococcaceae are abundant at 14%, but all the American Gut results I’ve seen so far have Ruminococcaceae somewhere in the top 4. So I don’t think that’s hugely relevant. I think Jeff Leach is the outlier at 23.2%).

So while that sweet, sweet potato powder may not give you that full spectrum firmicute high, it hits the important guys really, really hard.

Talk about “targeted therapy.”

Add to that the fact that, unlike other prebiotic fibers, with Resistant Starch we have a cheap, high dosable, abundant supplemental source in the form of potato starch (thanks Bob!).

And that, ladies and gentlemen, is the reason Resistant Starch, in the form of raw potato starch, is officially the body hack of *maybe* the decade.

— Heisenbug

P.S. — I’ll be back with more thoughts on what this all means in terms of optimal dosing and prebiotic combinations in subsequent posts.


37 thoughts on “Gut vs. Gut: This is how & why Resistant Starch is working.

  1. Thanks for taking the time to spell all that out. You should offer your services to others who get Am Gut results.

    What’s even more impressive about RS as a laser-guided weapon, different types of RS stimulate different species of probiotics. RS2 (potato starch) targets different species of bifido than does RS3 (cooked and cooled potato starch). Several types of RS4 (manmade) are shown to also do the same, but I think the results are always muddied so people don’t realize that potato starch is more effective than a frankenfood.

  2. Hi, I think these past few posts are wonderful and give me much to think about. I’m glad Tim seems to think so, too. I kinda like Nikoley, but his reaction to you seems bizarre. I just don’t get it.
    Anyway, never mind. Thanks for putting this information out there. It will take me a while to digest, so to speak, and connect a few dots for myself.

  3. CatherineakaCate
    You have me hooked! I did finally try the RS (PS) after returning from Middle East refugee camp, diving Red Sea with GI difficulties x six months. PS had me dialed in in three days. (PHD eater)
    Unbelievable, thanks all.

  4. Do the biome results tell us enough to compare the nasties of Tim, Jeff, and Michael? I recall that Tim mentioned his were very low, and I would imagine the same would be true for Jeff and Michael, too. However, as RS from potatoes seems to target specific bugs for promotion, maybe it’s more specific in its demotion, too. Thanks for the interesting blog.

    • That’s an interesting point. When you aren’t dealing with specific species (ie, specific pathogens), it’s hard to really say what’s a “nasty” and what isn’t. Depends on the study at hand. Some say Prevotella are good, some say bad. But it is interesting to note that, of the three, Jeff seems to also have the least Proteobacteria, a phylum which does include pathogenic (but also benign) species. Whether that’s good, bad, or neutral is unclear.

  5. Guess Nikoley forgot the honey 🙂
    Thanks for a great post. There could an explanation in the offing for the positive effects of whole grains, which I try to prevent at all cost. Am beginning to see several dots connecting. For a while suspected Peter D was writing this blog. Michael cleared that up

  6. I have to say….I am in love with your blog! As someone who has been diagnosed in the last two years with a few autoimmune issues – celiac, hashimoto’s, ezcema/psoriasis, and endometriosis (yes, all of those in the last 2 years!) – I have been doing much research on gut flora. I’ve even submitted samples to uBiome, though I’m still awaiting analysis. I currently follow a paleo-ish diet, but I’ve found the stress variable to play a leading role in symptom exacerbation. I am a recovering type-A workaholic. You are clearly ahead of the curve in your ability to connect the dots and I look forward to future posts. If you need blog ideas, I’m also interested in the SIBO connection (yep, diagnosed with that too), issues with FODMAP/histamine foods and the MTHFR pathway. Thanks!

    • That’s quite a lot you are dealing with. On the bright side, it’s likely that at least some of this would overlap in causation. Hope what you find here sheds some light. Have you tried any gut-related therapies or interventions yet?

      • Agree in the overlap. I’m currently on Autoimmune Paleo (due to several other IGG sensitivities) and lots of gut-healing supplements (vitamins, herbs, probiotics, etc) with my nutritionist. Ironically, before my Celiac diagnosis, I thought I was just fatigued from being overworked. It wasn’t until I went gluten-free that I then got Ezcema/Psoriasis and SIBO. I believe that there was likely so much inflammation from the Celiac that once my intestines started to heal, I somehow became MORE sensitive to other foods. And with the gluten-free diet changes, my gut flora changed. As a side note – I previously worked for a molecular diagnostics company, so am aware of gene expression, but I think (and hope!) future research will expose the microbiome as the switches for many of these autoimmune genes.

      • Lisa it might be just possible that when dropping wheat you also lost the benefit of the RS that is present in whole wheat, albeit in small amounts and coming with a sh*t load of the stuff you don’t want and caused you a lot of aggravation. RS from a different source without the baggage might help you along. Just my two cents.

      • That is my hope as well.

        Your history/pattern fits remarkably with what I’ve pieced together from research regarding gluten free, autoimmune, and flora composition. I really wish we had your pre-gluten free gut sequencing results.

  7. Mr. Heisenbug ,
    I agree with all the benefits of Butyrate and other SCFA’s produced by fermentation of Resistant Starch and particularly Raw Potato Starch.

    I take a combination of ingredients to achieve high levels of Butyrate throughout the gut.(My Formula contains Large dose of Potato Starch & Wheat Bran and small amounts of Inulin, Fructooligosaccharide, Whole Psyllium seeds with husk intact, Glucomannan from Konjac, Pectin , Gum Arabic and Guar Gum. I also include the Herbs Neem and Turmeric in my recipe and take the Probiotic BIFILAC-HP (Clostridium Butyricum plus). I have only experienced good results.

    However, I am a bit worried for individuals who may be carriers of potential pathogens in the Gut and genetically predisposed to develop certain Autoimmune conditions . Professor Alan Ebringer at King’s College , London and others have linked Ankylosing Spondylitis and Crohn’s Disease with consumption of Starch which leads to an overgrowth of the causative organism Klebsiella in Genetically predisposed individuals. My understanding is that Starch that escapes digestion by Human Amylase and arrives in the Colon is available for microbial fermentation. It is still STARCH. All you need at this stage for fermentation to take place is suitable enzyme systems and I suspect many undesirable microbes have this team of enzymes (eg. Pullulanase). In any case, the pathogenic microbes may be able to use metabolites produced by the beneficial microbes for growth.(Hydrogen, Carbondioxide, Methane , etc). No?
    My question is: Is Resistant starch really a Prebiotic (SPECIFIC for desirable beneficial microbes) or is it merely COLON FOOD for microbes that are able to ferment it and use it for growth and replication, including the bad guys? Has anyone done any research to find out if Potato Starch or RS supports or does not support the growth of potential pathogenic microbes that are part of the microbiota?

    I think we are concentrating too much on the reported undeniable and potential benefits of Resistant starch and particularly Raw Potato Starch without addressing the possible undesirable effects.
    What do you think?

    • Hi Ashwin. As I tried to communicate in this post, I believe the answer might lie in ensuring a proper pH throughout the gut, to ensure that beneficial microbes can effectively compete for fiber substrates. I am familiar with the Klebsiella research. Klebsiella is a gram negative organism that thrives in a more alkaline pH. So the theory is that, with the right amount and diversity of fiber, a suitably low pH can be maintained that allows beneficial microbes, and not pathogenic ones, to compete for prebiotic fiber. Is RS a prebiotic? Depends on the intestinal environment, probably.

  8. Just got my results back and they are strangely like Jeff Leach’s where my Ruminococcaceae is 32.4% and Lachnospiraceae is 10.7%. but I eat everything in large amounts, no special diet and have always had hard time gaining weight. White, 43, 6’1 and 160lbs. They say Jeff is as not common but trying to understand this high Firmicutes with us. After these two my next abundant is Clostridiales 8.3% and Bacteroides 6.4% and high Genus Anaerostripes at 2.7% and fold 23x. Where does one go to understand very different gut ratios from average American?

  9. I once read a research study that showed that ascorbic acid (vitamin C) had very good results in the gut (which is a good thing, since most of it washes out through the gut rather than absorbing, unless one is taking a liposomal version). It’s said to lower the pH as well (not surprising, given its own pH). I wonder if some serious dosing of AA through the gut as a sort of clean-up-sweep prior to a sudden major dose of prebiotics and resistant starch would be useful.

    I also wonder how things like activated charcoal would affect the gut. I read a study on mice I think it was where a regular dose of the stuff extended lifespan so extremely my eyes almost fell out — I couldn’t believe it wasn’t national news. I wondered if it had that effect because it was “cleaning out” something that just needs doing in a way that isn’t permanently destructive. It’s a bummer that it is so unworkable to test this kind of thing at home, rendering it all black box for us. I mean oneself as opposed to pricey mail-away tests (even where those are possible).

    I could buy a microscope I just don’t think that would help LOL.


  10. I’ve not seen any discussion of heavy metals, which, when present significantly alter the bacteria in the gut. (Many have heavy metal issues and don’t know it. They’re everywhere. If you have metal filings, you have heavy metals affecting your gut.)

    So, how do you factor that in? I’ve got mercury and had a bad gut for quite a while despite many measures taken to ‘fix’ the gut. I’m told that as long as I have mercury (which I’m chelating now with ALA) my gut is not going to be in balance.

  11. Heisentbug—-this is really great stuff you are putting together. I wonder if you can comment on the work of Ray Peat/ Andrew Kim….their view seems to be the opposite of Jeff Leach’s…i.e. they recommend eating as little fermentable fiber as possible because fermentable fiber generates endotoxin which negatively impacts the body. Peat even recommends taking antibiotics and charcoal periodically to keep the colon sterile. The mouse/charcoal study is frequently cited in support of this recommendation. Jeff on the other had beleives we should eat as many different types of fiber as possible to ensure intestinal health. Very confused…any thoughts about what is the right answer?? thanks for all you are doing!

  12. Hi- I have a question, not sure if anyone knows, but my organix acid test showed extremely high levels of DHPPA, which is a toxin of the clostridium species and can leave you with colitis, confusion, skin issues and the such. Now, there are over 100 species of clostridium; so are they all bad? It states it’s toxin B, but not the specific strain and everything else is perfect. Is potatoe starch good for me if I combine certain probitics with it? Any help would be great! Thanks!

  13. Hi everyone

    I’m a sufferer of Ankylosing Spondylitis – and am aware of the Klebsiella link to the disease.

    I have been gluten and corn free for 22 years – which has caused huge improvements in my condition. I speculate that this has something to do with the decrease in intestinal permeability (as confirmed by Dr Fasanos recent research on Zonulin) I still get some gut issues though!

    I have a Sheeps milk with streptococcus thermophilus – which seems to keep the balance – I also add sunflowers, sesame and pumpkin seeds.

    In a quandary about RS – my brain is says it is bad news for me. But have also read that RS feeds microbes that can strengthen the immune system. What to do – any views ?


  14. Hi. My 4 year old son has autism. I am confused abiut SFCA priductiins benefits in his case. I read that one theory is too much SFCA production screws up the brain chemistry.

  15. “He eats onions, garlic, and leeks every day — foods with a high amount of fermentable fructooligosaccharides, including scFOS.”

    Does he eat all of his garlic, leeks and onions raw? Or is that not necessary? Are FOS generally heat stable?

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