Artificial sweeteners induce glucose intolerance by altering the gut microbiota

Well now, this is very interesting on a number of levels. I don’t know if you recall, but it was some years ago the paleo Diet community (perhaps Low-Carb as well) was a buzz with how the use of artificial sweeteners led to physiologically high insulin levels in test subjects. Connecting the dots: elevated insulin —> insulin resistance —> glucose intolerance ~~~> diabetes(?)

Now let’s bring in a few additional dots to connect.

  1. I’ve made quite a bit of noise about the poor glucose tolerance in subjects put into a state of ketosis. [1][2]
  2. Heretofore, I’ve never seen #1 discussed (and it’s uniformly ignored in paleo / LC circles currently—very telling), but only physiological insulin resistance; so-called, because it’s supposedly ‘no big’ and reverses in a few days with normal carbohydrate intake.
  3. Never asked—that I notice—in regard to #2, is why fasting blood gluclose of 120-130 mg/dL is pre-diabetes and very very bad for someone who eats normal levels of carbohydrates, say 150-300g per day, but very very good in people who eat low carbohydrate or ketogenic.
  4. Recall what happened to so many people who introduced various forms of Resistant Starch and later, even Dirt-Based Probiotics back when we began our little revolution around here? Two things were observed by hundreds of low-carb dieters basking in ‘the wonders of physiological insulin resistance and glucose intolerance’ (when they did a carb ‘cheat’): their fasting BG numbers decreased (for many, down below 100) and they began experiencing 2nd-meal effects when they did that ‘cheat.’

Now, low and behold, we have some pretty good science to hang our hats on in terms of unifying all of the above experimentation and anecdotal observation. In Nature.

Artificial sweeteners induce glucose intolerance by altering the gut microbiota

Jotham Suez, Tal Korem, David Zeevi, Gili Zilberman-Schapira, Christoph A. Thaiss, Ori Maza, David Israeli, Niv Zmora, Shlomit Gilad, Adina Weinberger, Yael Kuperman, Alon Harmelin, Ilana Kolodkin-Gal, Hagit Shapiro, Zamir Halpern, Eran Segal & Eran Elinav

Non-caloric artificial sweeteners (NAS) are among the most widely used food additives worldwide, regularly consumed by lean and obese individuals alike. NAS consumption is considered safe and beneficial owing to their low caloric content, yet supporting scientific data remain sparse and controversial. Here we demonstrate that consumption of commonly used NAS formulations drives the development of glucose intolerance through induction of compositional and functional alterations to the intestinal microbiota. These NAS-mediated deleterious metabolic effects are abrogated by antibiotic treatment, and are fully transferrable to germ-free mice upon faecal transplantation of microbiota configurations from NAS-consuming mice, or of microbiota anaerobically incubated in the presence of NAS. We identify NAS-altered microbial metabolic pathways that are linked to host susceptibility to metabolic disease, and demonstrate similar NAS-induced dysbiosis and glucose intolerance in healthy human subjects. Collectively, our results link NAS consumption, dysbiosis and metabolic abnormalities, thereby calling for a reassessment of massive NAS usage. [emphasis added]

Well, of course, paleo dieters (LC or otherwise) never advocated for NAS usage anyway. But equally of course, they’re in rampant use pretty much across the board in weight loss or diabetes controlling diets (LC or otherwise). My interest is in the connection to the gut microbiome and how this independently jives with what at least hundreds out there have observed in terms of correcting the ‘healthful wonders of high fasting blood glucose and glucose intolerance’ in a low-carb or ketogenic diet context.

Ira Flatow of Science Friday had a 12-minute interview with study co-author Eran Elinav yesterday on NPR, which I was fortunate to accidentally catch while out and about. It’s a really good overview of the whole thing and gives added detail into the two human trials conducted, one observational and one controlled.

And here’s an article in The Scientist that covers everything in more depth as well

A previous study showed that sucralose can alter the rat gut microbiome—specifically, by decreasing beneficial bacteria—but this latest work pinpoints a microbe-mediated mechanism by which artificial sweeteners might influence glucose metabolism, said Yanina Pepino, who studies how non-caloric sweeteners influence glucose metabolism at the Washington University in St. Louis School of Medicine.

Elinav and Segal’s team observed that mice given a 10 percent solution of one of three types of commonly consumed commercial artificial sweeteners—saccharin, sucralose, or aspartame—in place of regular drinking water had elevated blood-glucose levels after 11 weeks compared to mice given either a 10 percent glucose solution or water alone. The researchers used saccharin for subsequent experiments as this artificial sweetener showed the most pronounced effect on glucose levels in preliminary trials. Mice fed a high-fat diet plus the 10 percent saccharin solution showed the same effect on glucose metabolism as animals given an even higher saccharin dose—comparable to the US Food and Drug Administration’s (FDA’s) upper limit for safe human consumption. [emphasis added]

You catch that?

  1. Artificial sweeteners produced worse glucose metabolism than if they were fed the same dose as plain glucose (or water). Kinda strikes me like my exercise analogy. You know: couch potato climbs flight of stairs, heart races to 200+ bpm; he concludes he can’t handle any exercise at all. So, perhaps to have a physiologically normal glucose metabolism, you need to ingest some glucose. Use it or lose it?
  2. A high fat diet didn’t help any. In fact, it was as bad as mice given even higher doses of saccharin (presumably as part of a normal chow diet).

Four weeks of treatment with gut bacteria-depleting antibiotics reversed the glucose intolerance in mice that continued to receive saccharin. This led the team to examine whether the microbiomes of the mice were somehow altering glucose metabolism. Transplantation of feces from non-antibiotic-treated mice that consumed saccharin- or glucose-containing water into germ-free mice within six days induced the same blood-sugar elevations in animals that were never themselves exposed to the sweeteners.

There’s a bit of an ambiguity there—”mice that consumed saccharin- or glucose-containing water“—so hopefully someone with access to the full text can clear that up. But the takeaway here is that it looks like the NAS are causing a gut dysbiosis either in terms of increased bad bacteria, decreased good bacteria, or both (that antibiotics corrects—probably as a general reset or “weeding” deal); a high fat diet (LC) doesn’t help, or actually makes things worse.

You know what that last sentence in the quoted text means, don’t you? That’s causality.

Using shotgun metagenomic sequencing on the fecal samples, the researchers showed that mice given saccharin or those that received a fecal transplant from saccharin-fed mice had a different microbiome composition compared to mice given sugar or no sweeteners. [emphasis added]

Perhaps it’s because we evolved with a taste for sweet and there’s a reason behind it; that in reasonable doses, it could not only be not harmful, but beneficial?

The team also found similar glucose metabolism and gut microbiota changes in humans.

In a cohort of 381 non-diabetic volunteers who answered diet questionnaires, those who regularly consumed artificial sweeteners—particularly those who consumed the highest amounts—showed higher fasting glucose levels, poorer glucose tolerance, and different gut microbe profiles compared to those who did not consume such sweeteners. The difference between the two populations remained even after correcting for body mass index.

Further, the team exposed seven young, healthy volunteers who did not have a history of artificial sweetener consumption to one week of the FDA’s maximum acceptable daily saccharin intake, and continuously monitored their glucose levels. Four of the seven volunteers showed a poorer glycemic response at the end of the week compared to their baseline responses. Those who showed no metabolic response to the sweetener had no change in their gut microbiomes, while those who exhibited the worst glycemic responses at the end of the week showed a different gut microbiota profile after sweetener exposure. Fecal transplants from two artificial sweetener-responder volunteers into germ-free mice resulted in a similar gut microbe profile and glucose intolerance as did transplants from saccharin-consuming mice. But the same transplants from two non-responder volunteers had no such effect in germ-free mice. [emphasis added]

Wow. I mean, that’s pretty compelling stuff, to me. Everything aligns consistently: mouse-to-mouse, human-to-human, and even human-to-mouse. What would be interesting to further explore is the actual diets of those seven participants. It looks like the only variable that changed was everybody got the same amount of saccharin and otherwise kept their same diet (nice control of confounders). So, knowing the differences in baseline diet might give clues as to why four of the seven got compromised guts and glucose intolerance, while the other 3 did not. I’m placing my bet on: beans!

…Although, it might also be sugar, leading to a most ironic finding: ‘eating sugar is protective against the negative effects of artificial sweeteners in sugar metabolism!’

Hey, maybe Pay Peat was right all along about sugar. I’ve been having some interesting results with daily orange juice consumption of about 10-12 oz—half in the morning, half at night—typically taken in a 50/50 mix with water or club soda. So, now that we’re increasingly establishing the healthfulness of starches in rational doses, what’s next: Safe Sugar! May we live in interesting times.

…Oh, one more thing. The 14 comments so far in that The Scientist article are really laughable. Not one single commenter get the point: it’s the microbiome, stupid.


  1. To Reiterate, Just In Case You Missed It: No Elevated Ketone Levels in the Inuit.
  2. More Uncovering of the Inuit Myth: Stefansson and Anderson Belleview Experiement; Compromised Glucose Tolerance.

Richard Nikoley

I'm Richard Nikoley. Free The Animal began in 2003 and as of 2021, contains 5,000 posts. I blog what I wish...from health, diet, and food to travel and lifestyle; to politics, social antagonism, expat-living location and time independent—while you sleep—income. I celebrate the audacity and hubris to live by your own exclusive authority and take your own chances. Read More


  1. Walter on September 20, 2014 at 16:00

    I wonder how stevia plays with the microbiome?

    • Richard Nikoley on September 20, 2014 at 16:20

      It’s a reasonable question, Walter.

      This is one case where “more study is needed” actually rings true. So, they say NAS, but it’s not all of them. But it looks on the surface that their study design and control is good, so they can see if it’s the non-calorie sweet aspect, or is it a chemical compound. Each can be studied in isolation for good confounder control.

      Also, why stop there? Virtually every chemical compound food additive could be tested in this way as a single variable, with controls.

      Glucose tolerance is also an excellent marker. Perhaps they could add inflammation markers too.

  2. Malcolm Klein on September 21, 2014 at 10:05

    What’s your take on this critique?

    It does seem rather unlikely that three molecules as chemically unrelated as nutrasweet, sucralose and saccharin would all be metabolized by gut bacteria in such similar ways as to cause dysbiosis? And it looks like most of the work was only on saccharin- nutrasweet and sucralose were only tested in terms of glucose intolerance, which could be due to effects on post meal hormones?

    • Richard Nikoley on September 21, 2014 at 10:19


      It’s not a critique, it’s a screed by someone who has missed the point, just as 100% of the commenters (last I saw) on the article in The Scientist. It’s the microbiome. All his piffle about “chemistry” is non-sequitur.

      Incidentally, they did preliminary tests on all three NAS, and results weren’t identical. They continued with saccharine because that was the most pronounced result.

    • Bret on September 21, 2014 at 10:28

      “It does seem rather unlikely that three molecules as chemically unrelated as nutrasweet, sucralose and saccharin would all be metabolized by gut bacteria in such similar ways as to cause dysbiosis?”

      It does stimulate the desire for more/different testing, but I don’t find it particularly unlikely. We are talking about synthetic chemical compounds with arguably no micronutrient value whatsoever. They act as a tax on the body, not a boon. It doesn’t surprise me much at all that such substances affect the gut population in similar negative ways.

    • Richard Nikoley on September 21, 2014 at 10:41

      Moreover, they used both GLUCOSE and WATER as CONTROLS.

      The guy’s “critique” amounts to: “I’m a CHEMIST and I can’t figure out how it could be, so it’s ‘bullsweet'”

    • FrenchFry on September 21, 2014 at 11:23

      Just quoting from this article:

      “You might as well take random chemicals out of a lab and test them, because chemically, this is essentially what they did”.

      Just this tells you the irrelevancy of the whole critique. What they did is NOT AT ALL like taking random chemicals out of a lab, they studied sweeteners that are eaten by the truckloads. This fact makes the study highly relevant.

      Furthermore, it does not matter that the chemist can’t see how this makes sense “chemically, physiologically, or pharmacologically”. What the study authors are doing is to observe in a controlled environment a particular response (variations in glucose intolerance) as a function of some particular ingested sweetener. From the clear different responses they get, they go a step further and try to narrow down the possible factors to the gut microbiome. What they had found is quite remarkable: the gut microbiome seems to be a key in this response, regardless of HOW the microbiome is doing this in the presence of this or that sweetener. Note moreover that the lead researcher added (in the interview linked by Richard) that they can’t speculate what this response would be in the long term. Answering this question is a high priority in my opinion. Would the microbiome adapt and increased glucose intolerance come back to normal ? How knows ? they have to study that because some people have been ingesting these artificial chems for YEARS!

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

      The other interesting thing is that the effects were seen in 100% of the mice (and 100% not, under the controls) but only in 4 or ten people.

      The most logical explanation is that all the mice were on the same diet, but the humans were not. So, next question is, what kind of diet is protective?

    • FrenchFry on September 21, 2014 at 11:47

      Well then, take some hard-core long time keto-dieters and some blue-zones dieters. Do the experiment with these guys. Any bet ? 😉

    • Richard Nikoley on September 21, 2014 at 12:08

      Well, hopefully the full text will have at least a dietary questionnaire for the 7 participants in the controlled portion, to give some clues about what sort of diet is more protective.

      I’m betting on higher fermentable fiber. But the possibility exists that it could be higher sugar consumption. Keep in mind, these were participants who don’t use artificial sweeteners which in this day and age is more likely to mean that they consume at least fair amounts of sugar.

    • Bret on September 21, 2014 at 14:02

      “Keep in mind, these were participants who don’t use artificial sweeteners which in this day and age is more likely to mean that they consume at least fair amounts of sugar.”

      I’d say it depends on how health-conscious the subjects are. There seems to be a pretty strong skepticism toward sugar in the mainstream now. Wouldn’t surprise me if they weren’t sweet tooth kind of folks.

    • Serth on September 22, 2014 at 07:22

      I think the critique raises some interesting questions. It is true that all three of these chemicals have vastly different structures. So it would seem unlikely they are metabolized by the microbiome in the same manner. What they do have in common is that all of them activate the sweetness receptors in our mouths. Does this create a signaling cascade that somehow modifies the behavior of the microbiome – and when they do not receive the carb payload they are expecting they act differently? Or is it somehow random that three differently structured chemicals somehow affect the microbiome metabolism – all with similar blood glucose tolerance changes in the host? Sadly, we’ll probably have to wait several years to know the answer. I think the fact that antibiotics resets the behavior is a clue not to be looked over. It seems like that means that either saccharine is increasing a population of bacteria or modifying their behavior in some way. And this same modification gets moved over with fecal implants. Very very curios. And this isn’t even considering other more natural sweeteners that are basically non caloric – stevia, monk fruit, xylitol, etc…….

    • TheJeebus on October 7, 2014 at 12:59

      Great theory (mouth sweet receptors).

      Another interesting question would be if this is adaption based, i.e. after a while of having mouth receptors triggered, yet no calories to work with, changes happens, or if it’s a constant response to no calories in itself, that over time leads to other changes.

      Nitpick: Xylitol is 2.4 cals per gram, and about 1:1 in sweetness with sugar, so it’s not even close to non-caloric.

  3. tatertot on September 20, 2014 at 20:13


    • Richard Nikoley on September 20, 2014 at 20:34

      Tim wants to make sure you’re testing. Are you? 🙂

    • tatertot on September 20, 2014 at 21:34

      Yeah, sorry. Test! Test or Die!

      I wrote a big long response, but it went in the bit bucket. I’ll try again with no links or cut and pasted quotes.

      Anyway, Art Ayers was saying last year that he thought artificial sweeteners were acting like antibiotics in our gut. He even found a new class of ‘taste enhancers’ just approved that look even worse than the artificial sweeteners.

      Just another reason to stay away from man-made crap. Much of the ‘fiber’ in fiber bars and on labels is derived from man-made fibers, who knows what those really do, either?

      Like my hero Jack Lalanne said, “If man made it, don’t eat it!”

    • Bret on September 21, 2014 at 09:12

      “Just another reason to stay away from man-made crap.”

      Could not agree more. From a commonsense perspective, artificial sweeteners are but a band-aid for a sugar addiction. A false sense of security by which people perpetuate their sick love affair with processed, addictive crapola.

      Hell, even sugar itself is arguably an artificial sweetener. We take a substance surrounded in nature by abundant fiber and micronutrients, and we isolate it, concentrate it, and pump our food full of it. That is undeniably anything but natural. Should it be any surprise that negative consequences result from eating it?

      Of course, [what the mainstream calls] artificial sweeteners are even worse. Here, instead of putting an otherwise natural substance in a completely fucked up, inappropriate, unnatural context (as with sugar), we are synthesizing chemical compounds in a laboratory — and concentrating them as well. Gag.

      Why don’t we just restrict ourselves to whole foods to the maximum extent possible? We humans seem to be doing a shitty job of replicating nature with industry and technology. So until we perfect that process (and I suspect we never will), why don’t we just use nature? Call in the industry and technology only when absolutely necessary — complicated pregnancy, broken arm, syphilis, etc.

      By the way, Tim, one method I have developed to avoid the occasional cyber black hole is to compose my long comment in a notepad program (currently using ‘Notes’ on the iPad), and then copy/paste into the browser. That way, if the tron monster eats it, I can just repeat the paste process in the blink of an eye. I’m sure you’ve noticed that nearly all my comments are long-winded, so I have developed this technique out of sheer necessity. 🙂

    • FrenchFry on September 21, 2014 at 09:58

      Can’t agree more. I keep saying that in a few places but “debates as usual” go on and on :
      – fat vs carb
      – animal protein vs plant protein
      – sugar or no sugar
      – …

      These debates become superficial when one sticks to varied real whole food most of the time. But when presented with the choice “added sugar” vs “sucralose / aspartame / ace. K / other 0-cal lab chemical”, my pick is quick 🙂

  4. elmo on September 20, 2014 at 20:24

    in the last few years as my digestion got worse and worse i was buying a lot of these Walmart branded zero calorie drink mixes that were sweetened with aspartame and ace k. not sure how much effect it had but i was drinking at least a gallon a day of this stuff, much more in the summer. then recently i read some article that said one of the artificial sweeteners releases methanol(?) when its broken down and supposedly the methanol is highly toxic and kills beneficial bacteria.

    • TheJeebus on October 7, 2014 at 12:49

      That would be aspartame. Methanol is indeed toxic. In high enough quantities. From what I’ve read, the amount of methanol coming from aspartame is no different than what comes from fruit, through degradation of pectin.
      This is why aspartame has been my preference NAS. We know exactly how it breaks down and it’s all normal stuff. I’m of course open to studies like this and may reevaluate my NAS intake.

  5. Artificial sweeteners induce glucose intolerance by altering the gut microbiota | Bydio on September 21, 2014 at 01:59

    […] By Richard Nikoley […]

  6. leo+delaplante on September 21, 2014 at 06:11

    a sugar conglomerate study on stevia is sure to follow

    • Richard Nikoley on September 21, 2014 at 08:23

      That may be, Leo, but it doesn’t diminish this research establishing clear causality that three specific NAS cause a particular gut dysbiosis that in turn compromises glucose tolerance in both mice and humans, holds up to a sugar control in mice, and that the dysbiosis is transplantable mice to mice and human to mice.

  7. Geoffrey on September 21, 2014 at 07:28

    “they began experiencing “2nd-meal effects” when they did that ‘cheat.'”

    What does 2nd-meal effects mean? that after eating one meal, with moderate levels of carbs, you want another?

    I’m still trying to adjust to adding carbs back into my diet. Would love to have a blood sugar reader to know where I’m at. I don’t want to go to my doctor, because he doesn’t seem to know much about diet, cholesterol, and statins, and I don’t want to get into explaining to him what my body is going through after being on a very low carb diet for a few years. I’m still working on moderation of carbs, I find it difficult, but going back into that ketosis state does not feel like a long term option anymore. I now realize that the leg/foot cramps that I was getting at night, and had never had before, were from that low carb diet and some nutrient deficiency. I don’t think I had any other symptoms.

    Be well everyone and I enjoy reading and following this blog. I’ve never been much of a blog person but this one seems to speak to stuff I’m going through and have no local community or individual people to talk about it with. In many ways, we as a group, as in everyone reading this post, are on are own with our health and diet. I certainly can’t get advice from my PCP, and at this point don’t trust him with my sugar and cholesterol readings. Thanks.

    • Bret on September 21, 2014 at 09:28

      Geoffrey, I often like this kind of forum better than the PCP or even in-person social acquaintance route.

      This way we don’t have to restrict ourselves to the perspective of just one person or a small group of people. We can communicate with many people — and the more blogs/forums we visit, the more perspective we get.

      The trade-off is that we have to sift through the information, and possibly experiment, and see what works for and applies to us. But the result from doing that is so much better than only taking one person’s opinion (even if he/she has a certificate saying he attended medical classes for four years).

      To ramble on further, this kind of a blog forum might not be necessary if we had true capitalism (i.e. competition) among health practitioners, which would force the good answers to take root and the bad answers to go away. But of course, we don’t have that. We have a silly, bureaucratic filtration system that only allows a limited number of people to play the game. So the result is that we get a limited perspective (and limited amount of competence) from going to the health providers.

      In our current economic/political scheme, I will take the wisdom of the crowd via blogs and forums over the medical establishment any day of the week.

    • Richard Nikoley on September 21, 2014 at 10:07


      The 2nd-meal effect, formerly called ‘the lentil effect’ is a post-prandial glucose response to dietary carbohydrates that is less than expected and persists to a 2nd-meal.

  8. FrenchFry on September 21, 2014 at 07:42


    What results are you referring to with respect to orange juice ? I read somewhere that orange juice is good for lowering oxidative stress.

    For example, if your meal is high in carbs and fat (sure combo to create oxidative stress), drinking orange juice would be a good thing:

    So I’d be interested in reading what you experienced with OJ.

    A little remark about “safe macro”. I think it is better to state which food or food combo is “safe”, and which is not. Macros by themselves are neither safe nor unsafe. On the other hand, foods and food combos are either one or the other. But that’s my opinion.

    • Richard Nikoley on September 21, 2014 at 08:19

      Re OJ, on the days I use it as described, I feel better, have more energy, have better sleep and maybe get up for a piss once on average instead of 3 on average.

    • Simas on September 21, 2014 at 12:48

      When I was very low-carb I started getting up 2 times to piss which was very unusual for me, I would never wake up at night at all actually. I also developed some very uncomfortable sensation in the bladder, which after reading Paul’s blog I realized could be related to carb intake. After some time struggling, I increased carbs and it got better, increased even more and it went away. No more getting up at night to piss.

    • JG on September 29, 2014 at 02:31

      When I started drinking a glass of orange juice with meals my longstanding ‘brain fog’ went away. Now I feel clear headed and alert and my energy levels are consistent all day. I feel more balanced, less muscle aches, fatigue, etc. nothing else works that well for me. Not caffeine, starch, fat, vitamin D, you name it. A small amount of fruit sugar makes a big difference and I think it’s beneficial. If I do the peat thing though I feel worse so I think a balance of starches, sugars and proteins is good

  9. Beans McGrady on September 21, 2014 at 10:28

    Just a little note that is tangentially related.
    Coca-Cola has been selling a product called Coca-Cola Life in Argentina, Chile, and I think some European countries for a year or two. It just became available in Mexico.
    It is sweetened with a mix of sugar and stevia. Pepsi has a version too, but I don’t know the name.
    I think it is a fairly direct response to the growing number of people avoiding artificial sweeteners. By using stevia they produce a product that is significantly lower in calories than one with all sugar, but avoid the nasty chemicals.
    This is similar in my mind to Wal-Mart carrying organic vegetables in a lot of places.
    Even in our very controlled economic world, the remaining vestiges of a market still allow for consumer demand to have a tremendous impact. (Mcdonalds is also opening a chain of restaurants that serves fast-ish food based on local and organic foods designed to accommodate the spectrum from meatasaurous to vegan, as well as gluten free, with out people really noticing)
    Good to remember when the people put forward the notion that in a market we would be slaves to the big bad companies.
    Jury is out on stevia for me, but It does hold out some hope that the basic “eat real food” approach could win out in the long run.

    • Richard Nikoley on September 21, 2014 at 10:47

      Stevia is a plant extract, right? Yea, so would be very interesting to test that. But in that case, it’s a natural sweetener, not artificial.

      Anyway Beans, that sound like what I’ve been seeing on shelves here, sodas with 10 calories. Not sure what the mix is.

      I say, if you want a soda pop, then:

      1. mix your favorite fruit juice 50/50 with club soda. I do this regularly. I like carbonation.

      2. Go get a Hansen’s or similar product, not only sugar instead of HFCS, but the flavors are natural, not artificial. But do it sanely.

      Dose makes the poison. Also, it could turn out that a certain amount of sugar (or honey, or maple syrup, etc) is better for you than both too much more, or none at all. Could even have a hormetic effect.

  10. j3nn on September 21, 2014 at 11:29

    Mainstream NAS may not be accepted or popular in Paleo circles, but sugar alcohols are widely used in many LC/Paleo recipes, and we have already established how detrimental they can be to digestion, so it’s not a far cry to extend their use to bacteria alteration as well.

    This is all so interesting! Good times, indeed.

    • FrenchFry on September 21, 2014 at 11:40


      I don’t think sugar alcohols are that bad (some better than others for sure). They are natural and truly fermented in the gut. But you have to be quite selective, you can’t just eat whatever, and I don’t think it should be a staple thing. What I have handy at home is just these two:
      – erythritol: about 0 fermentation, it does not reach the colon, and has 0 metabolic effect. You pee it eventually (never tasted my pee post-ingestion though …)
      – xylitol: it has too many benefits to ignore and I never experienced anything weird in my gut from using it. Granted, I don’t use it every day or in large amounts.

      Anyway, if someone asks me, those are the only 2 I recommend.

  11. GTR on September 21, 2014 at 14:23

    So how about Xylitol – it clearly does change gut biome – how about the direction?

    “xylitol feeding caused a clear shift in the rodent faecal microbial population from Gram-negative to Gram-positive bacteria. In human volunteers a similar shift was observed even after a single 30-g oral dose of xylitol. All animals were capable of adapting to 20% dietary xylitol and an accompanying enhancement of the ability of caecal and faecal flora to utilize xylitol was observed.”

    • Bret on September 22, 2014 at 07:31

      The Wikipedia entry for xylitol reads:

      Xylitol is naturally found in low concentrations in the fibers of many fruits and vegetables, and can be extracted from various berries, oats, and mushrooms, as well as fibrous material such as corn husks and sugar cane bagasse, and birch. However, industrial production starts from xylan (a hemicellulose) extracted from hardwoods or corncobs, which is hydrolyzed into xylose and catalytically hydrogenated into xylitol.

      So, you have the natural substance phenomenon, albeit isolated and concentrated, in the first half, and a fairly disconcerting production process described in the second half.

      But still, despite the processing, industry did not concoct this stuff out of nothing but an idea. It still has a base in nature.

      I would definitely think that the dose makes the poison, as Richard & SusieCruising said. A diet of 80% or 90% xylitol would bring negative effects, I am sure.

      The most important question is: What were these rodents eating before the experiment and/or as controls to the experiment? If they were eating sewage or the S.A.D. (redundant), then it might not be such a surprise that xylitol brought a relative benefit. I would be curious to see how the results of xylitol consumption stack up against those of a diverse whole-foods diet with plenty of fermentable fibers.

    • FrenchFry on September 24, 2014 at 01:40

      In Finland, xylitol has been some sort of staple item after WWII. Finish studies have reported quite a lot of benefits, but mechanisms for those were unclear. I bet you that the gut microbiome is responsible for many of those 🙂 Something that caught my interest is the xylitol fed mum during pregnancy and benefits transmitted to the baby. If that does not “smell like gut-flora-spirit” then I’ll be damned 😀

      80%-80% xyltiol diet ??? what is this ??? that’s crazy. Xylitol can be part of a whole foods diet, it is part of mine, it is a great sweetener for treats, which I don’t indulge in at all. I don’t think there is any harm in having xylitol once in a while. Actually, better that than maltitol or sorbitol … Anyway, I am probably biased because I never felt anything weird by consuming xylitol. Half of the time, I mix it with erythritol (cheaper and no metabolic effect) when I bake something. But soon, I will experiment with tiger nut flour, that should cut down the sweetening by a lot.

  12. Michael44 on September 21, 2014 at 23:58

    Organic Blackstrap Molasses is meant to be choc full of minerals.

    From what I’ve read,, sugar cane roots go way way down into the soil – many many feet – allowing them to pick up lots of minerals.

    Of course, because the molasses is the left over concentrated mass after the last sugar extraction, there is a risk that non-organic molasses may also have concentrated chemical residues from pesticides etc.

    • Bret on September 22, 2014 at 07:55

      “…there is a risk that non-organic molasses may also have concentrated chemical residues from pesticides etc.”

      My concern over industrial pesticides is somewhat assuaged of late. Paul Jaminet has a PHD post from 2010 citing a UCal@Berkeley report as follows:

      About 99.9% of the chemicals humans ingest are natural. The amounts of synthetic pesticide residues in plant foods are insignificant compared to the amount of natural pesticides produced by plants themselves. Of all dietary pesticides that humans eat, 99.99% are natural: they are chemicals produced by plants to defend themselves against fungi, insects, and other animal predators….

      We have estimated that on average Americans ingest roughly 5000 to 10,000 different natural pesticides and their breakdown products. Americans eat about 1500 mg of natural pesticides per person per day, which is about 10,000 times more than the 0.09 mg they consume of synthetic pesticide residues.

      I am not trying to grant Paul and the PHD some kind of Revered Prophet and Good Book statuses, respectively (uber religious style), but this kind of perspective is helpful at a time when the real rage is all about the synthetic pesticides. They may not be as disastrous as the foodie herd would have us believe.

    • Bret on September 22, 2014 at 07:58

      Forgot to cite one more noteworthy detail (ibid):

      They also note that 57% of natural plant compounds tested have proven to be carcinogens in rats and mice, compared to 60% of synthetic compounds tested.

    • Richard Nikoley on September 22, 2014 at 08:03

      “My concern over industrial pesticides is somewhat assuaged of late.”

      Awesome find, Bret.

    • Richard Nikoley on September 22, 2014 at 08:27

      “Forgot to cite one more noteworthy detail”

      File that under “if you drink enough water in short enough space of time, your brain will swell and you die.”

      …Some years ago a couple of ignorant radio talk show hosts did a water drinking challenge one morning for their listeners. One of them (a woman) actually died.

    • Bret on September 22, 2014 at 09:24

      Yeah, exactly. To clarify, I was not trying to argue that the natural compounds of plants are harmful, but rather, that the popular fear of industrial pesticides is likely overblown, given the comparison.

  13. SusieCruising on September 22, 2014 at 06:39

    Perhaps it’s as you say – dose makes the poison.

  14. Michael44 on September 22, 2014 at 21:27


    I do agree with you that we have and do take in lots of natural poisons, but are our bodies actually adapted to taking in the synthetic kinds in the quantities we do (even if the quantities are a lot less relative to the natural toxins ingested)?

    • GTR on September 23, 2014 at 15:21

      And what do these artificial substances combine into when they react? Even simple combinations of substances that are acceptably safe alone can lead to bad stuff when combined – eg. ascrobic acid reacting with sodium benzonate preservative creating cancerogenic benzene. A frequent combination in soft drinks. Random combinations of synthetic chemicals are not tested for safety… A producer tests his chemical alone, finds its acceptable by the government, then it goes into the world when it meats lots of other chemicals to ract with…

  15. Michael44 on September 24, 2014 at 00:34

    GTR said –

    “A producer tests his chemical alone, finds its acceptable by the government, then it goes into the world when it meats lots of other chemicals to ract with…”

    Yes GTR, that’s my understanding of what is happening too :-

    For eg:
    Chemical A is considered safe if kept below x parts per million ratio (or wotever).

    Chemical B is considered safe if kept under y amount.

    Chemical C is considered safe if kept under…… etc etc

    But when they are added together (at amounts just below each of their supposed individual toxic threshholds), what is likely to result? Toxicity?

    You said

    “Random combinations of synthetic chemicals are not tested for safety… ”

    Yes, that’s my understanding of what happens too. They aren’t testing combinations.

  16. Jack N on October 30, 2014 at 12:24

    Have you seen this paper?

    I find it intriguing that aspartame increased the roseburia spp population in mice.

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