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Migrating motor complex – MMC

Migrating motor complex – MMC

Zespół Be Compleat

Diet and lifestyle


Today a few words about one of the key elements that needs to be taken care of in the process of treatment, as well as prevention of recurrence of SIBO, namely the migrating myogenic motor complex (MMC).

The MMC is the electrical activity of the smooth muscles of the gastrointestinal tract, which is activated during fasting, between digestion cycles, so in between meals and at night.

MMC begins its activity about 90 minutes after a meal, and ends with the start of the next meal. Its activity consists of 4 phases, the duration of which is about 90-180 minutes (according to other sources, 122-172 minutes and 113-230 minutes):

  • Phase I is a period of rest, with virtually no contractions
  • Phase II consists of intermittent, irregular contractions of low amplitude
  • Phase III consists of short series of regular contractions of high amplitude (most relevant in the context of SIBO)
  • Phase IV is a short transitional period, leading back to Phase I

The MMC is often referred to as our “internal vacuum cleaner” or “housekeeper” because of the role it plays in our body. This is because it is responsible for moving undigested food debris from the small intestine to the large intestine. When the MMC is damaged, leftover food can linger in the intestines, creating conditions for the proliferation of bacteria and, as a result, can add the proverbial brick to the development of SIBO. Studies have shown that in people struggling with SIBO or IBS, there may be a problem with the operation of the third – and most important – phase, which in some subjects was not present at all. In others, on the other hand, the MMC cycle was shorter and the strength of contractions was reduced.

How does MMC damage occur?

The causes that can lead to damage to the MMC or inhibit its function can be really quite a lot.

It is certainly worth mentioning here post-infectious damage to the MMC as a result of bacterial infection (e.g. Campylobacter jejuni, E.coli, Shigella, Salmonella), when CDT toxin begins to be produced. Antibodies against it are produced, but in some cases (as a result of a “mistake” by the immune system) antibodies against vinculin – a protein of Cajal cells – begin to be produced, which in turn initiates the work of MMC. This results in permanent damage to the MMC, which predisposes to the development of SIBO and IBS on an autoimmune background (especially the diarrheal form).

Other factors that impair MMC function:

  • Impaired sugar metabolism – many SIBO patients struggle with insulin resistance or hyperglycemia; unstable sugar metabolism effectively inhibits phase III MMC activity
  • Hypothyroidism – according to studies, SIBO can affect up to half of those diagnosed with hypothyroidism; hypothyroidism is associated with delayed gastric emptying and impaired intestinal peristalsis, and patients often complain of constipation problems
  • Neurodegenerative diseases (such as multiple sclerosis or Parkinson’s disease)
  • Head injuries, e.g. as a result of an accident
  • Chronic use of medications like PPIs, antibiotics, steroids, hormonal contraception
  • Parasitic infections
  • Lyme disease, yersiniosis
  • Celiac disease
  • Vagus nerve dysfunction – you can read more about how important the vagus nerve is for proper gastrointestinal function in our previous posts
  • Eating disorders – studies suggest that gastric emptying and intestinal transit are slower in some people with anorexia
  • Long-term stress – both mental and physical (excessive physical activity)

How to improve the work of the MMC?


Pay attention to maintain about 3.5-4 to even 5h intervals between meals and a 12-14 hour fast between dinner and breakfast.

Between meals, you are allowed to drink only water, it is necessary to limit snacking and chewing gum (it contains polyols, which are among the products that are easily fermentable and can aggravate gastrointestinal complaints). All these activities will stimulate the digestive tract, which has an inhibitory effect on the MMC complex.


Maintaining an optimal diurnal rhythm linked to sleep as well as meal times will ensure the proper rhythm of the digestive tract, including the maintenance of regular times for the stimulation of gastric juices, the work of the liver, pancreas and intestines.

Sleep is the basis of health, so we should take great care of its quantity as well as quality

  • regular hours – try to keep an eye on specific times for falling asleep and getting up. The optimal length of sleep is an individual issue, however, the time of sleep between 22:00 and one o’clock at night is critical for the physical and mental regeneration of the body.
  • blue light – this is the greatest bane of the 21st century. It disrupts our diurnal rhythm and the production of melatonin, which lets us know it’s time for sleep. Limit your use of electronics at least 30 minutes before bedtime. Ideally, limit your exposure to blue light from the time the sun goes down – blocking glasses or red lamp bulbs are useful in this regard.
  • exposure to the sun – make sure that your exposure to the sun’s rays takes place during the morning hours, e.g. take a minimum 15-minute walk every day, and arrange your workspace near a window. This is when we regulate the secretion of melatonin for the evening.
  • bedroom – it is worth taking care of the environment in which we sleep. Our bedroom should be ventilated, cool, dark and quiet.


One of the most recommended practices to activate the vagus nerve is meditation or similar relaxation techniques. Slow and deep breathing – at a rhythm of 5-6 breaths per minute – can also be effective, increasing baroreceptor activity and activating the vagus nerve. Yoga also shows an activating effect on the vagus nerve.


Increased tolerance of high FODMAP products – that is, products with high fermentation potential will have a great impact on the activity of the MMC complex, but also on the diversity of intestinal bacteria. Therefore, when following a low FODMAP diet, the most important step will be to reintroduce the eliminated products and introduce them into the diet in an appropriate, tolerable dose.


In order to support the MMC complex, substances with a prokinetic effect, i.e. accelerating gastric emptying and intestinal transit, are used. This is a key component of therapy in the course of SIBO. The most commonly used are:

  • drugs such as prucalopride, itopride, naltrexone (prescribed by a gastrologist during bacterial eradication)
  • natural substances: oil of rosemary, peppermint, thyme in capsule form, iberogast, ginger or chamomile.



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