Complain about ongoing gut issues like bloating, chronic constipation, diarrhea, or a seemingly unending cycle of gastrointestinal malaise, and after months of poking around without a definitive culprit, you’re likely to be told you have Irritable Bowel Syndrome (IBS). You may be given medications, supplements, told to eat more fiber, less fiber, avoid gluten—sometimes this works, and sometimes your symptoms don’t budge at all. Up to 25% of the worldwide population has IBS, making it the most common gastrointestinal (GI) disorder, but there’s a tendency to throw hard-to-pin-down stomach ailments into this bucket without further diagnosis. Good news: Research has now shown that a condition called SIBO is the underlying cause for the majority of IBS, and on average 60-70% of people with IBS have SIBO—and may not have to live with it.
SIBO is a condition where normal gastrointestinal (GI) bacteria accumulate in the small intestine at havoc-wreaking levels. Normally, the small intestine (SI) has very low bacterial counts, and goes about its job digesting food and absorbing nutrients. But when too many bacteria accumulate in the SI, they harm its structure and function. These bacteria compete for food, chowing down on fermentable carbohydrates, which produces lots of gas - enter bloating, pain, gas, belching, nausea, reflux, constipation, diarrhea or both. The bacterial overgrowth also damages the SI tissue, causing food intolerances and malabsorption, which can show up as nutrient deficiencies and anemia.
In functional medicine we are always looking for the cause of the cause of the cause-and this applies to SIBO as well. While we naturally want to alleviate symptoms, we also want to get closer to the root cause to help prevent recurrence. About one-third of SIBO cases are gone for good after one treatment, but two-thirds of SIBO cases are considered chronic and need some sort of periodic treatment to keep symptoms at bay. There are myriad causes of bacteria build-up in the SI: slow motility, structural issues in the GI tract that can block or trap bacteria; back migration of bacteria into the SI from the large intestine; or incoming bacteria that are not being killed by normal paths like stomach acid, enzymes, bile or the immune system. One of the most common underlying causes is food poisoning (could look like the stomach flu) which damages the nerves that sweep bacteria down through the SI. Other causes include hypothyroidism; abdominal adhesions from previous surgeries, infection or endometriosis, low stomach acid; medications like opiods, proton pump inhibitors or antibiotics; or certain disease states such as scleroderma, diabetes or Crohn’s disease.
I know that’s a lot to digest (pun intended). But here’s the easy part: SIBO is diagnosed by a non-invasive breath test that can be done at home (some gastroenterologists perform it in the office). Patients consume a lactose containing solution and then collect breath samples every half hour for about 3 hours. These samples are analyzed for the presence of gases made by the overgrowth of bacteria: hydrogen, methane, and hydrogen sulfide.
The treatment for SIBO depends on what type of gas is produced and can consist of antibiotics, herbal antimicrobials, or an elemental liquid diet. A SIBO diet is also initiated to help with symptom relief by decreasing the type of food the bacteria “eat” to produce gas. There are a few different types of diets, but all are low in FODMAP foods (fermentable types of food, like beans and onions for example). A promotility agent is then started to help keep the SI bacteria moving down the SI instead of setting up camp.
Although SIBO has been around for a while, it is just starting to gain more attention in the medical community.. If you have symptoms consistent with IBS or SIBO, bring it up with your doctor or find a one who specializes in its treatment. And if you’re unsure, my best advice is to follow your gut.