The process causing your stomach to rumble is not a sign of hunger; however, allowing it to complete its function may aid in preventing bloating, gas, and related symptoms.
A coordinated digestive process that unfolds between meals could hold the key to resolving digestive problems for many individuals.
Following a meal, a mechanism known as the migrating motor complex (MMC) sets in motion specialized contractions that help cleanse the upper gastrointestinal (GI) tract by expelling unwanted debris like bacteria and mucus.
These contractions differ from the rhythmic waves of muscle activity responsible for propelling food through the entire digestive system. Instead, the MMC operates more like a diligent street sweeper, meticulously clearing away lingering particles.
This MMC plays a crucial, albeit somewhat time-consuming role in ensuring efficient digestion. Its operation can only occur during non-eating periods, as it strives to maintain a balance of microbes and their byproducts in the proper regions of the GI tract by sweeping away residual food particles that bacteria tend to thrive on.
Without the MMC functioning as it should, bacteria may venture out of their designated area in the colon and into the small intestine in pursuit of undigested food. While these bacteria aren’t inherently harmful, their presence in the wrong place can lead to small intestinal bacterial overgrowth (SIBO), resulting in symptoms like bloating and gas.
According to the medical book “Clinical and Basic Neurogastroenterology and Motility” published in 2020, a malfunctioning MMC can cause food particles and bacteria to stagnate in the small intestine.
“This condition has been found to increase the likelihood of developing SIBO,” notes the book. “The large intestine houses distinct bacterial strains in significantly greater numbers than the small intestine. The MMC’s sweeping action helps prevent these colon bacteria from migrating into the terminal ileum, where they could colonize the small intestine.”
However, SIBO isn’t the sole digestive ailment associated with the migrating motor complex. Research has connected it to gut infections, gastroparesis (a condition impeding stomach emptying), and intestinal pseudo-obstruction, as detailed in a review in Nature outlining its role in various diseases.
Some experts even raise concerns that the dietary advice advocating for frequent, small meals might contribute to suboptimal MMC functioning. Overloading the digestive system with frequent feedings could potentially exacerbate uncomfortable GI symptoms.
Naturopath Nicole Peasnell, affiliated with the Kirsten Greene SIBO Clinic, cautions against the prevalent notion of consuming six small meals daily. “While we’ve been advised to graze on our food throughout the day, this approach doesn’t align with optimal motility,” warns Peasnell. “If we continually nibble on our meals, the MMC doesn’t have the opportunity it needs to carry out its essential cleansing and motility functions.”
A Deeper Dive into the MMC
The migrating motor complex primarily governs gut motility, regulating the transit time of food from the moment it enters the mouth until it exits the body. It operates on a cycle comprising four distinct stages with patterns of electromechanical activity occurring every 90 to 120 minutes.
The first phase, the longest, exhibits minimal contractions. The second phase features sporadic, irregular contractions. The third phase, the most active, showcases brief bursts of regular high-amplitude contractions, often causing gurgling or rumbling noises that can be mistakenly interpreted as hunger pangs. However, the act of eating interrupts this cycle from the first bite, restarting the extended process. The fourth phase signifies a short transition back to phase one.
Identifying a malfunctioning MMC isn’t straightforward, as there is no single diagnostic tool. Instead, tests for associated conditions can offer clues. A 2018 study suggested that assessing gut sounds might serve as a viable biomarker, akin to auscultation used to assess heart and lung function. Published in Sensors, this study employed a computer, specialized software, and an affordable acoustic sensing device to detect MMC cycles.
When the MMC Goes Awry
Researchers have gained insights into the MMC’s functionality by examining its intricate connections with gut hormones, such as motilin, and the nervous system. The enteric nervous system, often referred to as the “second brain,” initiates MMC activity. As a component of the autonomic nervous system, the enteric nervous system comprises a network of neurons that communicate via neurotransmitters to coordinate activities involving muscles, secretory glands, and the vasculature of the GI tract.
Severe enteric neuromuscular dysfunction is characterized by an absence of phase three contractions for eight hours. Additionally, the vagus nerve, a lengthy nerve linking the brain to major organs including the gut, plays a role in this mechanism. Patients who have undergone vagotomy, a procedure that partially removes the vagus nerve, retain MMC impulses in the small intestine but not in the stomach, illustrating the involvement of two distinct components of the nervous system.
Motilin, a gut hormone responsible for triggering muscle contractions that move food from the small intestine to the large intestine, also participates in MMC phases. Administering motilin to a patient can induce phase three contractions.
The MMC’s Role in Health and Disease
The migrating motor complex holds significance not only for digestion but also for facilitating the movement of food through the GI tract, aiding nutrient absorption, and preventing intestinal blockages. Various disorders have been linked to a disrupted MMC, as highlighted in a 2021 review in Nature.
Two such disorders are intestinal pseudo-obstruction, a painful condition characterized by the accumulation of partially digested food in the colon, and gastroparesis, a condition where the stomach fails to empty properly. A 2012 study in the Journal of Neurogastroenterology and Motility found that patients with Helicobacter pylori (H. pylori) infections were more likely to experience a lack of phase three activity, which typically normalized once the H. pylori infection was eradicated.
Fasting and the MMC
Restoring proper MMC function can be as simple as allowing it the time it needs to perform its cleansing duties, which involves spreading out meals.
Cedars-Sinai Medical Center suggests, “Rather than putting food in your mouth every hour throughout the day, consume the same amount of food but as distinct meals. We used to recommend five hours between meals, but at least four hours is now our recommendation.”
Additionally, avoiding snacking and refraining from eating right before bedtime can contribute to healthier MMC function. Cassie Madsen, a registered dietitian specializing in Gut Health and Nutrition, emphasizes the importance of consuming meals at regular intervals.
“Our bodies thrive on routines,” says Madsen. “When you disrupt your eating schedule, gut function may slow down and eventually halt. Is meal timing alone enough to make a difference? We don’t have all the answers yet.”
Nonetheless, maintaining a four to five-hour gap between at least two meals and extending the nighttime fasting period as much as possible may prove beneficial, particularly for those who have dealt with SIBO.
Exploring Other Rebalancing Approaches
Prokinetics, which promote gut motility, are currently under investigation from a pharmacological perspective. Natural prokinetics, including probiotics, traditional Chinese and Japanese herbs, ginger, curcumin, and specialized supplement blends, are also gaining attention.
While vagus nerve stimulation is a trending topic on social media for enhancing gut motility, it lacks substantial scientific evidence. Nevertheless, practices such as yoga, meditation, regular exercise, and deep breathing techniques are worth considering. These practices not only promote overall relaxation and stress reduction but can also have a positive impact on gut health.
