No, we are not talking about a physical motor vehicle…
Perhaps you were taking a deep dive into all things gut health trying to get to the root of your discomfort, and stumbled upon the Migrating Motor Complex (MMC). While the MMC is a bit of a less discussed topic, it is undoubtedly one of the most important when it comes to motility. In this post, we break down what the MMC is, the signs and symptoms of a dysfunctional MMC, its common disruptors, how a dysfunctional MMC plays a role in conditions like constipation, IBS, and SIBO, and our top tips to optimize the MMC’s action.
What is the MMC?
Putting it simply, the MMC describes the mechanism in our gastrointestinal tract (GI) that initiates a wave of muscle contraction through our stomach and small intestine (aka peristalsis) so that food is pushed through to the large intestine for further digestion and ultimately excretion.
This wave of contraction throughout the GI tract, initiated by our MMC, is essential as it keeps food moving through the organs of our digestive system so that the food can be properly broken down, its nutrients can be absorbed, and the waste products can be excreted (aka poop).
The MMC is naturally stimulated in a fasted state or about every 3-4 hours post-meal. This means that this wave of contractions will occur every 3-4 hours post-consumption of food or drink (or any form of calorie), alternatively aiding in digestion. So now you may be thinking about why you should care about the MMC if it occurs naturally. Well, the truth is the MMC can easily become disrupted and not function optimally if you are consuming calories consistently. But before we jump into common disruptors of the MMC, let’s recap what a dysfunctional MMC can look like.
Signs and Symptoms of a Dysfunctional MMC and Common Disruptors
As mentioned above, the MMC is an innate process; however, some behaviors and circumstances can disrupt this process, resulting in undesirable symptoms.
Common Signs and Symptoms of a Dysfunctional MMC:
- Constipation (this is arguably the most common symptom as the MMC is responsible for the movement of food through the GI tract!)
- Bloating (another common symptom given that digestion is impaired, and other conditions can develop like SIBO, etc.)
- Poor digestion overall and the feeling of food sitting (again, no surprise here! If you feel like your food is sitting, it most likely is given the MMC helps move things along!)
- Reflux (when our food sits in our stomach too long, the acid covered food can go back up into your esophagus causing this feeling of reflux)
- Need for assistance to go to the bathroom- like stool softeners
- Stomach cramping, nausea, vomiting
When the MMC is slowed, it can result in conditions like Small Intestinal Bacterial Overgrowth (SIBO) because food and bacteria are fermenting and sitting for longer periods than normal, resulting in constipation and enabling bacteria to build up rather than being cleared out. Additionally, given the slowed digestion and transit time resulting in digestive upset and constipation, a slowed MMC can be diagnosed as IBS. However, we like to think of it as the other way around, where the IBS is caused by MMC dysfunction and/or SIBO. Therefore, once the underlying cause of constipation, MMC dysfunction, and SIBO is resolved, then the symptoms of IBS will likely resolve too.
Disrupts to the MMC
There are a handful of reasons for the function of the MMC to become impaired, with one, in particular, being in your control and others not so much.
Common disruptors to the MMC:
- Consistently consuming calories and not waiting 3-4 hours between meals (remember, the MMC is triggered by a fasted state!)
- Chronic stress
- Food poisoning
- Traumatic Brain Injuries (TBIs)
- Vagus Nerve Dysfunction
From this list, the factor we can control the most is being mindful of our eating and drinking habits. So often I find this goes unnoticed by many of my clients who are subconsciously grazing on snacks throughout the day, drinking coffee slowly throughout their day, or drinking other forms of liquid calories, chewing gum, you name it! This is why bringing attention to your eating/drinking behaviors so that you are not consistently consuming calories and waiting 3-4 hours between meals can make a world of difference in your digestion, but also your blood-sugar balance, mood and energy, weight, and more!
Aside from your eating habits, your stress levels also impact your MMC. This is in part because of the gut-brain connection where the vagus nerve runs bi-directionally from the brain to the gut and is primarily involved with the parasympathetic nervous system, aka rest and digest. However, in times of stress, it is believed that the vagus nerve is effectively “turned off,” resulting in the MMC not being stimulated. This is why incorporating daily practices to help manage stress and even evaluating your lifestyle and environment to reduce overall stress can be beneficial not just for your digestion but for your whole body!
In contrast, you likely are not in control of if you have food poisoning or suffered from a TBI. Food poisoning may affect the MMC because the pathogenic bacteria may enter the small intestine and release toxins that may negatively impact the vagus nerve and, therefore the MMC. As you can imagine, this can be problematic given the MMC is not operating optimally to clear out this pathogenic bacteria or digest and help eliminate food. Additionally, TBIs may affect the MMC similar to chronic stress due to the gut-brain connection.
However, that is not to say you cannot do anything to help improve the functioning of the MMC. In terms of food poisoning, working with a health practitioner to help kill off pathogenic bacteria may be beneficial. When it comes to TBI some may find it helpful to engage in mindfulness practices such as meditation or take part in hypnotherapy classes that help “recalibrate” the vagus nerve and the gut-brain connection.
In more severe cases, in those suffering from chronic constipation and diarrhea a gastroenterologist can perform a scintigraphy test that measures transit time or how long it takes for food (or a capsule) to move through your GI tract.
Tips for MMC dysfunction
If you are skeptical of having MMC dysfunction or want to optimize your digestion in general, working with a health practitioner who will help get to the underlying cause of your symptomatology is highly encouraged. With that being said, in working with clients, we have found a handful of practices and modifications to be beneficial in improving one’s MMC function and overall digestion.
Top tips for MMC dysfunction:
- Bring awareness to your eating habits (snacking, drinking liquid calories, etc.)
- Wait 3-4 hours between meals and snacks
- Engage in practices to reduce stress
- Participate in breathing exercises and meditation (this improves stress response and helps stimulate your vagus nerve!)
- Try prokinetics (supplements that help stimulate the MMC by promoting peristalsis through the GI system – ex. Ginger, medicinal bitter, 5-htp – work with a practitioner to figure out which is right for you!)
- Move more with activities that you enjoy
- Concentrate on eating more fiber (soluble fiber, in particular, may be more helpful here)
- Focus on staying hydrated!
- Work on balancing blood sugar with well-balanced meals and snacks
The Bottom Line
The Migrating Motor Complex (MMC) plays a role in digestion and motility and is part of a more extensive interconnected system involving your gut, brain, and nervous system! The MMC is responsible for a wave of muscle contraction through our GI tract and is stimulated during a state of fasting. However, its function may be thrown off by eating too frequently, chronic stress, food poisoning, TBI, and more. Therefore, getting to the underlying cause of why your MMC may not be functioning optimally is key for improving digestion and motility.