What is the Migrating Motor Complex

The migrating motor complex (MMC) is a critical component of gastrointestinal (GI) health, yet it often goes unnoticed in discussions about gut health. This housekeeper-like process plays a pivotal role in maintaining a healthy gut environment. 

If the MMC is not working properly, a number of functional GI issues like IBS or issues like SIBO can occur. As a functional medicine practitioner, working with this process of the GI tract can bring some serious healing. So let's chat more about what the MMC is, its functions, and its implications for overall gut health. Ready? 💖

What is the Migrating Motor Complex?

The migrating motor complex is a cyclic, recurring motility pattern that occurs in the stomach and small intestine during fasting. It sweeps the GI tract clean during periods of fasting. This housekeeping function prevents bacterial overgrowth due to stagnant food contents. 

It typically starts in the stomach and migrates down to the small intestine, happening roughly every 90-120 minutes during fasting. If you've picked up that I keep using the word fasting....that's for a reason! Peristalsis (another rhythmic movement) happens with food. The MMC isn't activated until a fasting state is reached. This is because Motilin, a hormone secreted by the small intestine and responsible for the initiation of the MMC, is only secreted by an empty stomach!

The MMC is divided into four phases:

1. Phase I: A period of quiescence lasting 45-60 minutes where there is minimal to no contractile activity.
2. Phase II: A period of intermittent, irregular contractions lasting 30-45 minutes, which gradually increase in frequency and intensity.
3. Phase III: A short, intense burst of regular contractions lasting 5-15 minutes. This is the "housekeeping wave" that sweeps undigested food particles and bacteria out of the stomach and small intestine. What is also important to note is that peak hunger sensations occur during this phase. 
4. Phase IV: A brief transition period of decreasing activity leading back into Phase I.

Functions of the MMC

1. Clearing Residual Food Particles: The MMC acts as an internal janitor, sweeping away undigested food particles from the stomach and small intestine, preventing bacterial overgrowth and maintaining a balanced gut microbiota.
2. Preventing Bacterial Overgrowth: By moving contents along the GI tract, the MMC prevents stagnation and the subsequent overgrowth of bacteria in the small intestine, a condition known as Small Intestinal Bacterial Overgrowth (SIBO).
3. Regulating Hunger and Satiety Hormones: The MMC is also involved in the regulation of hunger and satiety through the release of motilin, a hormone that stimulates gastric activity and contributes to the sensation of hunger.

Implications for Gut Health

1. Small Intestinal Bacterial Overgrowth (SIBO): Impaired MMC function can lead to SIBO, characterized by bloating, gas, abdominal pain, and malabsorption. Proper MMC activity helps maintain a balance in the gut microbiota, preventing overgrowth or gut dysbiosis and associated symptoms.

2. Digestive Efficiency: Efficient MMC function ensures that the gut is effectively cleared between meals, promoting optimal nutrient absorption and digestive efficiency.

3. Gastroparesis and Dysmotility Disorders: Conditions like gastroparesis (delayed gastric emptying) and other dysmotility disorders often involve disrupted MMC activity. Understanding and supporting the MMC can be crucial in managing these conditions. Gastroparesis is common in diabetics and becomes more common as we age.

4. Functional GI Disorders: Many functional GI disorders, such as irritable bowel syndrome (IBS), are linked to motility issues. Enhancing MMC function through dietary and lifestyle interventions can alleviate symptoms.

Supporting the MMC for Optimal Gut Health

1. Fasting and Meal Timing: Allowing sufficient time between meals (about 3-4 hours) without snacking can help ensure the MMC completes its cycle. Overnight fasting for at least 12 hours can also support MMC activity.

2. Dietary Choices: A diet rich in whole foods, fiber, and low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) can reduce symptoms associated with SIBO and support MMC function.

3. Hydration: Adequate hydration is essential for maintaining proper motility and supporting the MMC.

4. Physical Activity: Regular exercise can enhance gut motility and promote a healthy MMC cycle.

5. Prokinetic Agents: In some cases, prokinetic medications or natural agents (like ginger or 5-HTP) may be used to stimulate MMC activity, particularly in those with significant motility issues. Always check with your primary provider before starting supplements. 

6. Stress Management: Stress can adversely affect gut motility. Incorporating stress-reducing practices such as meditation, yoga, or deep-breathing exercises can support healthy MMC function.

Conclusion

The migrating motor complex is a vital yet often overlooked aspect of gut health. By understanding its role and implementing strategies to support its function, you can significantly improve digestive health and manage various functional GI disorders more effectively. By adopting lifestyle and dietary practices that support the MMC, you can work towards achieve optimal gut health and well-being.

References:

Takahashi T. (2013). Interdigestive migrating motor complex -its mechanism and clinical importance. Journal of smooth muscle research = Nihon Heikatsukin Gakkai kikanshi, 49, 99–111. https://doi.org/10.1540/jsmr.49.99

https://histology.oit.duke.edu/MBS/Videos/Phys/Phys%208.4%20GI%20Motility/Phys%208.4%20GI%20Motility%20NOTES.pdf

Tack, J., Verbeure, W., Mori, H., Schol, J., Van den Houte, K., Huang, I. H., Balsiger, L., Broeders, B., Colomier, E., Scarpellini, E., & Carbone, F. (2021). The gastrointestinal tract in hunger and satiety signalling. United European gastroenterology journal, 9(6), 727–734. https://doi.org/10.1002/ueg2.12097