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What role FODMAPs?

February 2, 2019 By Dr. William Davis

A low-FODMAPs diet, the abbreviation for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, has been shown to reduce symptoms of irritable bowel syndrome, IBS, in studies conducted at Monash University in Australia. It is a diet crafted to remove fructans, fructooligosaccharides (inulin), galactooligosaccharides, lactose, fructose, sorbitol, and mannitol that human bowel flora metabolize. A low-FODMAPS diet is therefore designed to starve bowel flora that metabolize such sugars to survive. You can find a listing of FODMAPS eliminated and permissible foods here.

Does it work to reduce symptoms of IBS? Yes, it does. a FODMAPs-reduced diet reduces the bloating, abdominal discomfort, and unpredictable bowel urgency and diarrhea characteristic of IBS. The relief provided can be considerable.

Recall that most IBS is really SIBO. In other words, efforts to reduce diarrhea, cramping, and urgency typically ignore the cause: unhealthy changes in bowel flora that have ascended up from the colon and into the ileum, jejunum, duodenum, and stomach.

But the FODMAPs diet has triggered considerable confusion on what it accomplishes and what it does not accomplish, some even advocating it as a panacea. And is it good for you? Does it improve health? And what is the effect on the microbiome? Is it really an answer for health issues? Does reducing the symptoms of IBS lead to better bowel and overall health long-term?

I believe it helps to view a FODMAPs-reduced diet as nothing more than a symptom-reducing maneuver. By depriving bowel flora—both unhealthy undesirable species such as E. coli, Campylobacter, and Shigella, as well as desirable species such as Lactobacillus, Bifidobacteria, Akkermansia, and selected Clostridia—of necessary nutrients, bacterial counts in the gastrointestinal tract drop. With their reduced numbers, toxic components such as lipopolysaccharide, LPS, released with the death of undesirable microorganisms, is reduced, leading to less intestinal inflammation, less body-wide inflammation. FODMAPs reduction can therefore lead to reduced bloating, abdominal discomfort, and diarrhea that may or may not return upon resumption of FODMAPS consumption after several weeks to months of engaging in the diet.

But it is important to recognize that a low-FODMAPs diet also introduces undesirable changes in the microbiome:

  • Reduces bacterial species diversity—Species diversity is a consistent marker of better health.
  • Reduces Bifidobacteria substantially–BifidobacteriaΒ confer a number of important health benefits.
  • Reduces Clostridia species that produce butyrate—Butyrate is a mediator of a number of important health benefits.

Most important of all, a low-FODMAPs diet does nothing to restore a healthy microbiome, certainly not if you begin with severe dysbiosis, SIBO, or intestinal fungal overgrowth. Yes, it reduces the numbers of pathogenic bacteria but does not restore healthy balance of microorganisms. A diet temporarily deprived in FODMAPs cannot yield the increased butyrate required for intestinal healing. It does not restore the healthy balance of Akkermansia that increases the production of protective mucous. It does not replenish or seed the intestines with healthy species such as (our favorite species) Lactobacillus reuteri.

A FODMAP-elimination effort is therefore useful to reduce symptoms in IBS, SIBO, and dysbiosis, much like taking an opiate can relieve a headache from having a brain tumor—but symptom relief is not the same as disease reversal. So should you choose to follow a low-FODMAP lifestyle, recognize that it is only a symptom-reducing effort but does little to nothing to restore a healthy microbiome. It takes additional efforts to accomplish that, efforts such as supplementing curcumin to rebuild the integrity of the intestinal barrier, efforts to increase Akkermansia populations, and efforts to reduce fungal populations.

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Filed Under: Latest News Tagged With: diy health, diy healthcare, diyhealth, diyhealthcare, dr william davis, dysbiosis, fodmaps, grain-free, inflammation, prebiotic, probiotic, sibo, small intestinal bacterial overgrowth, undoctored

About Dr. William Davis

William Davis, MD, FACC is cardiologist and author of the #1 New York Times bestselling Wheat Belly series of books. He is also author of the new Undoctored: Why Health Care Has Failed You and How You Can Become Smarter Than Your Doctor.

Reader Interactions

Comments

  1. Bob Niland

    February 6, 2019

    Note: This reply is posted here due to on-going technical issues with Wheat Belly Blog articles and comment serving over the last few days.

    On the WB blog, a user wrote: «R u guys sure raw white potatoes have zero digestible carbs? Other websites claim they have lots of digestible carbs.»

    Since the carbs in potatoes are glucose polysaccharides, any that become available would show up as blood glucose, usually in the 30-60 minutes following the start of the meal (and, of course, subject also to whatever else is in the meal). If you have a meter, use it to check.

    re: «I have had my dad on the WB diet for 3yrs.»

    Which WB reference information are you using? The Wheat Belly Total Health (2014) program is essentially current, but the original 2011 book lacks some elements since added, particularly gut flora.

    re: «His scores are: Ldl: 169, hdl: 120, trigl: 50, small ldl particle to total ldl particle ratio:12.7%, fasting bg: 70-85, blood pressure 108/70 — 110/60.»

    Of those that matter (which the “LDL” does not), and making some assumptions for exact test names and units of measure, they appear to look great. Did that “LDL” report even indicate whether it was measured (Direct, aka DLDL) or calculated LDL-C, and if calculated, what function was used?

    re: «Of course his cardiologist wants him on lipitor, but according to WB, his scores dont call for cholesterol meds.»

    Is there some other symptom, or an adverse marker not so far reported here? If it turns out to be just a case of a dogmatic handing out statins to anyone with a pulse, I have some doctor-finding tips here.

    re: «Other websites claim there are lots of digestible carbs in raw white potatoes.»

    Post some links to any you think are germane. If I need to update my list of prebiotic fiber sources, I will.

    re: «My dad worries he is getting too many carbs from them.»

    Again, is this just a web fret, or is there some other issue at hand?

    re: «He eats at least 1 medium to large raw white potato a day — 1/2 in morning, 1/2 in evening. I always keep him under 15 carbs per meal, assuming the raw white potatoes are zero net carbs.»

    A caution I can suggest on that is: that’s a lot of prebiotic fiber, possibly too much if that’s the only source. Current Undoctored program guidance is 20 grams per day of mixed and varied prebiotic fiber. I only use a couple of slices of raw potato in my morning smoothie, for example.

    Relying on a single source might lead to a dysbiosis over time — a distortion of gut flora populations, due to favoring some microbe species and strains, and stressing others. Also, if someone has SIBO, that amount of prebiotic fiber per day would usually provoke a prompt and unpleasant reaction. Chances are that if a SIBO reaction was present, you would have mentioned it.
    ________
    Blog Associate (click my user name for details)

    • Therese Reynolds

      February 7, 2019

      Wow! Thank you for the fabulous response. Very much appreciated. My dad has a family history of cardio vascular disease, he has a calcium score from 3 yrs ago of 30, not 300, …30. Three zero.

      He is 5’8″ and on WB his weight dropped 40lbs and has has been a steady 155-160lbs for past 3yrs.

      Cardiologist wants him on Lipitor just because of basic ldl score.

      Thank you for info about possibly giving him too large a serving of daily raw potatoes. He doesn’t get the SIBO symptoms, but good to know about limiting his prebiotics from any one source.

      Links to websites claiming lots of net carbs in raw white potatoes:

      https://www.eatthismuch.com/food/nutrition/white-potatoes,2093/

      https://www.myfooddiary.com/foods/1140198/potato-raw

      https://www.carb-counter.net/vegetables/1333

      https://www.calorieking.com/foods/calories-in-fresh-or-dried-vegetables-potatoes-raw-flesh-skin_f-ZmlkPTcwOTY5.html

      • Bob Niland

        February 8, 2019

        Therese Reynolds wrote: «My dad has a family history of cardio vascular disease…»

        Given that, it would be useful to know the actual LDL-P Particle Number from what I presume was an NMR lipoprotein panel. The 12.7% ratio is well under Undoctored program target, but if the P# itself is higher, that might suggest some other tests to run, such as Lp(a).

        re: «…he has a calcium score from 3 yrs ago of 30, not 300, …30.»

        That’s not super concerning, but does suggest that a follow-up scan would be worthwhile to detect a trend. If possible, using the same clinic, machine, time of day and radiologist would provide the most comparable number.

        Also, statins do nothing (or less) to reverse Agatston calcium scores. You may have seen here: How to Reduce Your Heart Scan Score

        re: «Cardiologist wants him on Lipitor just because of basic ldl score.»

        Normally, I’d say “find a real doctor”, but if that cardio ordered an NMR, it may not be a lost cause. Speaking of which, you didn’t report the TC (total cholesterol) from the basic lipid panel, and still haven’t indicated what that “LDL” was literally reported as (assuming you were told). If the TC was ~299, then it’s calculated LDL-C using the antique Friedewald equation (that utterly falls apart on low carb).

        re: «Links to websites claiming lots of net carbs in raw white potatoes:…»

        Thanks. One of those wasn’t at all useful. The others had varying estimates for raw net carb, from 13 to 17%, and all agreed on cooked net carbs, at 19%. They all also included skin. Consumption of raw skin in not recommended. I have no guesses on what, if any, contribution it might make to net.

        I’m not sure that ~15% net carb is real for raw potato, and continue to rely on Dr. Davis’ view on it. As I mentioned, a $20 BG meter would settle that pretty quickly.
        ________
        Blog Associate (click my user name for details)

        • Therese Reynolds

          February 10, 2019

          So i did what you suggested + bought a glucose meter – our pharmacist showed me how to use everything. πŸ™‚

          And I tested the raw potatoe impact on blood sugar.
          I took my dad’s BG before meal: 64 BG
          Then gave him only 1/2 medium raw potato. Nothing else.
          30mins after raw potato: 66 BG
          1hr after raw potato: 67BG
          Then he ate friday meat free salad dinner w/the other half of the raw potatoe in his olive + fetta + romaine salad w/ 3 cherry tomatoes, celery, olive oil, apple cider vinegar + 5 – 1 inch pieces of yellow pepper
          1hr after dinner (+2hrs after 1st 1/2raw potato raw potato): 66 BG. :-)!

          Looks like Dr. Davis is right and the other websites are wrong. :).

          And meter works – i used it on me + my mom totally works – i have much different BG than my dad –

          I will get out his blood test results and answer ur ?s about the ldl later this wk.
          BTW: his cardiologist, lovely guy, but not a believer in low carb diet or interested in WB at all – He did not order the in depth cholesterol panel – and he refuses to do another calcium score . He recomemd lipitor and low cholesterol, low fat diet.
          My dad’s awesome GP did the in depth cholesterol particle blood tests.

          I’ll get back to u with cholesterol info u gave and asked about.

          Thanks so much for you help. You put my dad’s internet reading fears to rest with person proof of his BG! And… he has no gas or ibs after raw potatoes. πŸ™‚

          I am delighted w/ur help.

          • Bob Niland

            February 10, 2019

            Therese Reynolds wrote: «… 64 BG … 66 BG … 67BG … 66 BG …»

            Neat. Those are pretty amazing numbers, and I presume you are aware that they are well within repeatability tolerance for consumer meters. Thank you for running that experiment.

            re: «Looks like Dr. Davis is right and the other websites are wrong. πŸ™‚»

            Well, let’s not be too hard on them. The net carbs of raw vegetables is actually not a simple matter to nail down. Common forms of calorimetry heat the substance under test, which is likely to depolymerize them, and then measure all the saccharides, and not just the simple ones.

            For a lot of complex and fiber carbohydrates, the only reliable “bomb calorimeter” is your own gut. For those that are glucose polymers, blood glucose is easy to check.

            re: «He did not order the in depth cholesterol panel – and he refuses to do another calcium score .»

            Depending on where you live, you may be able to get the calcium scan on your own. It’s $99 around here in Kansas. You’re probably already looking for another doctor, but so far, why you might need one at all isn’t obvious.

            re: «He recomemd lipitor and low cholesterol, low fat diet.»

            If he’s following that himself, then no further punishment may be needed.

            re: «You put my dad’s internet reading fears to rest…»

            Amazing. In general, it’s possible to find sites that contradict any position one wants to take, on any topic, and it’s not easy for people to figure out on their own what’s true (or at least, not false).
            ________
            Blog Associate (click my user name for details)

  2. Therese Reynolds

    February 12, 2019

    This is all so helpful. Thsnk you so ver much!
    To answer your questions about my dad’s recent cholesterol screening:
    Lipoprotein subparticles (VAP) TEST
    from Quest Nichols institute, San Juan Capistrano, CA

    Total Cholesterol: 302
    HDL: 120
    CHOL/HDL RATIO: 2.5
    LDL, calculated: 168. –
    LDL-C calc using Martin-Hopkins calc.
    Trigly: 50
    APOLIPOPROTEIN B: 123
    Direct LDL: 160
    NON-HDL Chol: 182
    LDL PATTERN: A
    LIPOPROTRIN (a) : 106
    LDL PARTICLE #: 1714
    LDL SMALL: 217
    LDL MEDIUM: 225
    HDL LARGE: 11214
    LDL PEAK SIZE: 229.3

    Should be worried about any of this? Any further test recomends? Or does this all look good?

    Again, thanks so much for all your guidance. …u had asked if i am followung 2014 WB or 1st WB book- 2014, as i had gotten both books and a bunch of WB cook books. I think there is only 1 new book i have yet to get – undoctored –

    • Bob Niland

      February 12, 2019

      Therese Reynolds wrote: «Lipoprotein subparticles (VAP) TEST»

      That would seem to be the new VAP (vertical auto profile). Dr. Davis’ original TrackYourPlaque program had target ranges for what VAP reported, and then the VAP itself got discontinued. Since it returned, I don’t know that he’s had a chance to re-frame what it reports, so I don’t know how that compares with the NMR assay results we more commonly see. The old VAP’s Lp(a) number in particular tended to be quite a bit different than the Lp(a) from an NMR.

      As before, the HDL is fabulous. The TG is great. Even though the LDL is the more recent Martin-Hopkins transform, the LDL and TC are still less interesting than the VAP numbers.

      If the new-VAP’s LDL-P Particle Number and Small LDL-P are comparable to those from an NMR, the P# is elevated on program targets, but my sense is that it, per se, doesn’t trigger any specific strategy, other than looking for other markers like CAC, Lp(a), and perhaps ApoE (genetic).

      If the Small LDL-P is comparable, it’s only 12.7% of the P#, which is well below program target less than 20%.

      The Lp(a) seems high, about 2× the upper limit for old-VAP on the program, depending on units of measure. This is apparently a familial marker, and although the Undoctored program has a strategy for it, that doesn’t include shoving the marker around. The main component is to increase the daily fish oil, to make that presentation less atherogenic. Other than the prebiotic fibers, what supplements are presently in use?

      Lp(a) can apparently be shoved around with new agents like PCSK9 inhibitors and IONIS-APO(a)-LRx. The key question is: do they also reduce all-cause mortality for someone following an enlightened ancestral diet (and at what cost, for PCSK9i — IONIS-APO(a)-LRx is still in trials). Expect exactly zero studies to answer that question.

      Perhaps the key thing here is to get that updated calcium scan. If the CAC score has retreated, arrested, or even increased slowly (less than 15% per year), there may not be any grounds for alarm or medical intervention — keeping in mind that we don’t have the full chart here (such as BP, inflammation markers, thyroid, dysbiosis), and I don’t make diagnoses in any case.

      re: «…WB book- 2014…»

      Wheat Belly Total Health is current insofar as diet and supplements. The Undoctored book, although newer, and with more coverage of self-directed healthcare, doesn’t get into Lp(a). You’d need an Inner Circle Membership for that material.
      ________
      Blog Associate (click my user name for details)

  3. Therese Reynolds

    February 13, 2019

    Wow! So helpful.
    My dad’s blood pressure in great : 110/60
    No noticeable swelling anywhere
    Walks 40-60mins 5Γ—/wk
    No signs of gut disbiosis
    Thyroid test fine,
    Supplements:
    1800 mg kelp (900mcg iodine)/day. Again thank you very much.
    Carlson very finest fish oil: 1 tbsp/day (tbsp, not tsp)
    Carlson cod liver oil : 1 tbsp/day
    Swanson efa provinial omega 7 1 420mg soft gel/day
    Pure encapsulation 1- Multi b +2- mineral 650 caps
    Mg citrate pure encap. 450mg 2x/day
    Table KCl salt w/food
    Potassium citrate 1- 200 mg capsule/evening
    Melatonin – new 20mg dose/night – for past 6 mo – high dose – our doc recomends no more than 10mg, but trying the 20mg as pure encapsulations is recomending 20mg dose to prevent dimesia, alzheimer disease. – no sign of either one, just figured it’d be worth trying.
    We left a message w/our gp today, asking if he will order NMR test. Do you know of how we could get it in NY w/out a doc’s rx? Labcore is nearby – stopped to ask the today, but they were already closed – they close early around here.

    Thanks so much for all your help. I was on the undoctored web for a bit – maybe 6 or 8 mo ago. I found undoctored confusing and difficult for a not-tech savvy person like myself. Specifically, the layout – I found it difficult to read through + navigate. This blog is easier on the eye and easier on my poor navigation skills. …So, i am hesitant to go back on undoctored.

    Thanks again, Bob. Amazing info you are sharing with me. I am most appreciative.

    • Bob Niland

      February 14, 2019

      Therese Reynolds wrote: «Thyroid test fine,…»

      “Fine” is usually “not fine” when the topic is thyroid. You can compare whatever you have (which is often just TSH) to program targets here.

      re: «1800 mg kelp (900mcg iodine)/day. Again thank you very much.»

      Food sources might push it over 1000µg. If thyroid antibody tests were all green, this is probably OK, but might be twice what is needed.

      re: «Carlson very finest fish oil: 1 tbsp/day (tbsp, not tsp)
      Carlson cod liver oil : 1 tbsp/day
      »

      Can you figure out how much DHA and EPA per day that is? For elevated Lp(a), the program suggestion is to increase from the usual 3000-3600mg to 6000.

      Also, CLO is not an encouraged source, due to possible modern ocean contaminants (esp. Hg), and excess vitamin A exposure.

      re: «Swanson efa provinial omega 7 1 420mg soft gel/day»

      Omega 7 isn’t a deliberate supplement on the program. If you’re doing that for conjectured cognitive benefits, you might have a look at some notes Dr. Davis posted to the subscription forum (basenote visible to non-subscribers).

      re: «Pure encapsulation 1- Multi b +2- mineral 650 caps»

      Can’t isolate that to study it. Got an Amazon ASIN or similar handle?

      re: «Do you know of how we could get it in NY w/out a doc’s rx?»

      Doubtful. There are several states in this country that are hostile to personal autonomy generally, and self-empowered healthcare in particular. NY is a contender for the most unfree. If you can’t find a real doctor, it might take medical tourism to work around that. If you want to fly to Wichita, for example, a CT calcium scan is $99 and 15 minutes from the airport.

      re: «I was on the undoctored web for a bit — maybe 6 or 8 mo ago. I found undoctored confusing and difficult for a not-tech savvy person like myself.»

      That’s unfortunate, because this blog format is really unsuited to detailed lab and supplement discussions. This thread, for example, is going to close to comments in a couple of days.
      ________
      Blog Associate (click my user name for details)

      • Therese Reynolds

        February 14, 2019

        Again, so helpful. I am very grateful. I will go back to the undoctored site and spend some time getting used to it. Since it has more info … and continued interaction help like your help here that will be ending, it is well eorth the effort to get used to the site format. -like having to get used to a new tablet or phone – worth the effort. Thanks so much for all this great help!

        If i dont respond again here, I will probably be tapping your marvelous brain on the undoctored site. πŸ™‚

        One question: could too much iodine actually increase the ldl? I am probably over doing it with the iodine. His tsh was in normal range on both lower and higher doses.
        Any other supplement recomends or food intake recomends – i already feed him the greases from the meats I cook him. And no processed meats.

        Thanks again. … next time I get on the computer, I am heading back to the undoctored site. πŸ™‚

        • Bob Niland

          February 14, 2019

          Therese Reynolds wrote: «…could too much iodine actually increase the ldl?»

          Suboptimal thyroid (esp. hypo) can aggravate heart disease, resulting, I’m informed, in calcium score growth.

          re: «I am probably over doing it with the iodine.»

          Dropping back to program suggested levels is all that’s needed. Although the RDA for iodine is likely too low, and true optimal is a bit uncertain, megadose (much over 1000µg) is likewise potentially a problem.

          re: «His tsh was in normal range on both lower and higher doses.»

          If it was over 1.5 µIU/mL, some actual thyroid testing is needed. TSH isn’t even a thyroid test. The reference ranges vary dramatically. The upper end is high even on the most recently revised ranges. The thyroid testing article linked earlier goes into all the gory details.

          re: «Any other supplement recomends or food intake recomends…»

          It looks like you are attending to the core, with perhaps some dose tweaking needed. We can discuss optionals on the forum.
          ________
          Blog Associate (click my user name for details)

  4. Therese Reynolds

    February 15, 2019

    Another ? – i checked – my dad’s last TSH trst was done June 2018
    TSH. 2.68

    I give him 900mcg iodine per day (1800mg kelp) should I increase or decrease an by how much?

    And how long shild I wait gefore doing his NMR test – his GP gave us a script for it today.

    • Bob Niland

      February 16, 2019

      Hmmm. I see that comments closed before I could get to this. Since you reported being a UIC member, the forum would be the ideal place to continue any discussion, or use any open thread on either blog (the cache gremlin on the Wheat Belly blog seems to have been tamed).

      Therese Reynolds wrote: «…my dad’s last TSH trst was done June 2018 TSH. 2.68…»

      Well, as you can see from the Thyroid Optimization Quick Reference page linked earlier, that pituitary (not directly thyroid) test result, if µIU/mL, is above program upper bound of 1.5, suggesting that some actual thyroid testing is needed. If you weren’t in NY, that might be easy to arrange.

      re: «I give him 900mcg iodine per day (1800mg kelp) should I increase or decrease an by how much?»

      I don’t tell people what dose of anything to take. The Iodine Quick Reference page linked earlier provides program ranges (which, historically have been as high as 500-1000µg, so 900 doesn’t seem alarming, but is above current program guidance).

      re: «And how long shild I wait gefore doing his NMR test — his GP gave us a script for it today.»

      If weight has been stable for at least 30 days, I’m not aware of any particular timing issues. I might suggest doing it fasting, as postprandial lipoproteins can be confounders (they can distort the conventional TG reading by up to 20%). I personally shoot for 10:00AM on draws, as a matter of consistency for those with circadian considerations, and as a matter of convenience for overnight fasting.
      ________
      Blog Associate

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