• The Migrating Motor Complex and SIBO


    The migrating motor complex (MMC) is a ‘cleansing wave’ of high-frequency, cyclic, contractions of the smooth muscle of the GI tract occurring between meals, that moves indigestible food particles from the small intestine into the colon. When you hear the “growling” sound in your belly this is your migrating motor complex at work.

    The MMC doesn’t just sweep food waste into the large intestine, but it also sweeps the small intestines clean of bacteria throughout the day. This is how our body naturally keeps 98% of our gut bacteria in our large intestine and only 2% of our gut bacteria in our small intestine, therefore preventing bacterial overgrowth in the small intestine (SIBO).

    Several studies have demonstrated that abnormalities in the migrating motor complex may predispose to the development of SIBO. (1, 2, 3)

    Research at Cedars-Sinai found that people with IBS experience cleansing waves 70% less often, compared to people without IBS. (4)

    The migrating motor complex only occurs when there is no food in the upper digestive system, if there is food in your stomach or upper small intestine the MMC won’t trigger and undigested food and bacteria won’t be flushed from the small intestine, 

    We know the MMC typically starts around 3 hours after a meal and a cycle lasts for 90 – 120 minutes. Because the MMC is deactivated when you are eating, an adequate fasting period between meals is necessary. 

    Grazing or snacking between meals will impede your MMC process. Meals should be kept to three a day with a period of ideally 5 hours between them, with no snacking. Clear liquids between meals – water, black tea, black coffee, herbal teas  – are OK.

    The MMC is vital in keeping bacterial levels low in the small intestine and in moving food particles into the colon before they become material for bacterial fermentation in the small intestine.  This is a very important mechanism in preventing the  overgrowth of bacteria in the small intestine and preventing relapse of SIBO post treatment,


    1. Vantrappen G, Janssens J, Hellemans J, et al. The interdigestive motor complex of normal subjects and patients with bacterial overgrowth of the small intestine. J Clin Invest. 1977;59:1158–1166. 
    2. Stotzer PO, Bjornsson ES, Abrahamsson H. Interdigestive and postprandial motility in small-intestinal bacterial overgrowth. Scand J Gastroenterol. 1996;31:875–880. 
    3. Husebye E, Skar V, Hoverstad T, et al. Abnormal intestinal motor patterns explain enteric colonization with gram-negative bacilli in late radiation enteropathy. Gastroenterology. 1995;109:1078–1089. 
    4. Pimentel M. A New IBS Solution. Sherman Oaks, Calif.: Health Point Press; 2006.