SIBO & MMC – Part III: When things go bad

This is part three of a five-part series. The parts are:

  1. What is the MMC and why we care
  2. What Influences the MMC
  3. When things go bad with the MMC
  4. Healing with drugs and herbs
  5. Healing with lifestyle measures


MMC stands for Migrating Motor Complex.  The MMC is the ‘housekeeper’ of your gastrointestinal tract. It cleans up the stuff that should not be there, moving stuff along when it is time for it to move along.  But some people have poor housekeepers and then things go wrong, very wrong.

What happens when your MMC is bung?

SIBO:  SIBO is covered in previous parts as well as this four-part series on SIBO.  The gist of the story is; if the housekeeper (MMC) is not working properly, the bacteria that should be moved on down to the colon (large intestine) hang around in the small intestine – like a drunken youth at a party causing all manner of havoc.

IBS: IBS and SIBO are linked, in fact, the latest thinking is the majority of IBSer have SIBO.  Research specific to IBS and the MMC found poor peeps with IBS had altered patterns of the MMC compared to healthy peeps as well as differing levels of motilin, which is important in the MMC (Deloose, Janssen et al. 2012).

Functional Dyspepsia: also shows an altered MMC pattern.

Obesity: Who is the chicken and who is the egg? As mentioned in Part II we see poor MMC in obesity.  However there is also a link with the MMC and hunger; so then ….. is obesity caused by a poor MMC or does obesity cause a poor MMC or what?  It would seem that it is not linked to anorexia (in terms of a poor hunger reflex) at least not in a causal way; any MMC issues that came with anorexia resolve on weight gain.

A range of other illness and disorders are linked to poor MMC function including, diabetes, gastroparesis, Chagas disease and more.

How do you know if your MMC is bung?

As mentioned – If you have SIBO your MMC is most likely bung.  Pimentel, Soffer et al. (2002) discovered that in peeps with SIBO, Phase III of the MMC is reduced or even absent (without any anatomic causes).  They tested this via antroduodenal manometry, which doesn’t sound like a lot of fun.

Some other tests I have seen mentioned that also look at gut motility in the stomach and small intestine (where the MMC operates) are:

  • Scintigraphy: a Gamma camera takes pictures each hour after a standard meal for four hours. I can’t figure what this tells you specifically about the MMC, if anything.
  • Wireless Ph and Motility Capsule: uses a non-digestible wireless capsule. It measures temperature, pressure and ph as it goes down.   It seems that this is not great in patients with an “incompetent ileocecal valve” (Camilleri and Linden 2016).  I’m not sure how this test would go in SIBO, given that a shoddy ileocecal valve is also potentially implicated in SIBO.
  • Breath hydrogen test – we learnt about these in the SIBO series. In terms of using breath tests to consider motility – the required fasting may not accurately reflect small bowel transit.  Also as lactulose is commonly used and itself increases motility, this could interfere with it.  Lastly, I am also not certain how you read motility into these tests.  I know some gases rise suddenly on reaching the large intestine.  At least they do in healthy peeps, for my first test this rise wasn’t clear as the gases were already so high (I know, poor me).

I am not sure if or how these tests are used in clinical practice or if much should be done with SIBO given these tests can be expensive or invasive or both and you probably have a bung MMC anyway.  But I am interested to find this out… do let me know if your know.

I also notice some folks in online forums talking about trying to gauge their ‘total gut transit time’ at home with eating certain things they will see in their poop e.g. beets (we spoonies are poop spotters anyway so no extra pressure there).  I suspect this is not terribly scientific, however, I did note one of the studies below got mice to swallow steel beads to assess transit time.  I am not certain of the link between whole gut transit and the MMC, as lots of stuff ‘goes down’ between mouth and bum (yes bad pun intended).  Don’t try the steel bead thing at home, you are not a mouse!

Coming Up

Next week we will look at both pharmaceuticals and herbs to improve a poor MMC.

Meanwhile go well in the direction of your health goals

Yours as ever

The WellbeingatWork(ohsonearly)DR.


I am not a doctor, I am also a spoonie* and one of my challenges is Small Intestine Bacterial Overgrowth (SIBO).  SIBO tends to reoccur after treatment in many cases.   So I am putting my research skills (I am a middle aged PhD student) into finding out what I can do to help improve my MMC and sharing that with others who also might have an unhappy MMC.  However given my area is not medical research some of this is pretty tough going (because academics never learnt the ‘write for a 10-year-old’ thing, actually some of them never learnt the ‘write for anyone at all’ thing).


*Spoonie = Poor sod living with chronic illness(es).


Camilleri, M. and D. R. Linden (2016). “Measurement of gastrointestinal and colonic motor functions in humans and animals.” CMGH Cellular and Molecular Gastroenterology and Hepatology 2(4): 412-428.

Deloose, E., et al. (2012). “The migrating motor complex: control mechanisms and its role in health and disease.” Nature Reviews Gastroenterology and Hepatology 9(5): 271-285.

Pimentel, M., et al. (2002). “Lower frequency of MMC is found in IBS subjects with abnormal lactulose breath test, suggesting bacterial overgrowth.” Digestive diseases and sciences 47(12): 2639-2643.

Szarka, L. A. and M. Camilleri (2009). “Methods for measurement of gastric motility.” American Journal of Physiology-Gastrointestinal and Liver Physiology 296(3): G461-G475.







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