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Why Your Digestive Issues Might Actually Be Due To SIBO (Small Intestinal Bacterial Overgrowth)
Bloating and IBS that won't budge? SIBO may be the hidden cause. Learn the symptoms, root causes, testing and natural naturopathic ways to restore gut health.
Written and medically reviewed by Dr. Courtney Ranieri, ND, a licensed naturopathic doctor registered with the College of Naturopaths of Ontario (Reg. #3726). Last reviewed July 2026.
If you experience bloating or discomfort regularly, or have been diagnosed with IBS and the usual treatments haven't helped, it's time to consider SIBO.
The saying 'too much of a good thing can be a bad thing' is especially true when it comes to bacteria in the digestive tract.
Humans have a symbiotic relationship with the bacteria in and on the body, working together to function. Gut bacteria protect us from pathogens, help us digest food, metabolize hormones, synthesize nutrients and absorb minerals. But when the bacteria normally found in the colon start to colonize the small intestine, it can quickly turn into SIBO.
What is SIBO?
Small Intestinal Bacteria Overgrowth (SIBO) is an overgrowth of bacteria in the small intestine. Only 1 to 6% of all the bacteria in the digestive tract should be found in the small intestine; the rest is in the large intestine. It's estimated that 80% of people with IBS are actually suffering from SIBO.
Symptoms of SIBO
SIBO symptoms look a lot like IBS, which is why it's hard to diagnose. Common symptoms are bloating, gas, burping, flatulence, heartburn, a sensation of fullness, constipation and/or diarrhea, abdominal pain, food intolerances, and low vitamin B12 or iron.
What causes SIBO?
SIBO is believed to arise when there's an issue with one of the body's protective mechanisms:
Low stomach acid: we need optimal stomach acid to kill off bad bacteria and break down food. When there isn't enough, food isn't broken down fully, bacteria feed on it, and this can lead to overgrowth. Low stomach acid is common and can be caused by stress, poor diet, aging, infections or medications.
Sluggish or slow bowels: the intestines are muscles that contract to push contents along. When they're not contracting optimally, food and bacteria stay stagnant and can proliferate. This may be caused by stress, thyroid disorders, medications and conditions like diabetes.
Antibiotic use, food poisoning, poor eating habits, low pancreatic output and conditions affecting motility can also contribute.
How do I test for SIBO?
SIBO is under-diagnosed and often misdiagnosed. The gold standard for testing is a non-invasive breath test. Bacteria in the intestine produce hydrogen and methane gases, so testing their levels helps determine if there's an overgrowth. A licensed Naturopathic Doctor can provide this testing, which is especially important if you experience IBS symptoms but standard treatments haven't helped.
How do you treat SIBO?
The first key is to correctly diagnose SIBO and address the root cause. Treatment focuses on bringing bacteria levels back to normal, preventing them from proliferating again, and optimizing a healthy microbiome. Dr. Courtney Ranieri, ND focuses her treatment on optimizing nutrition, moderating bacteria levels, rebuilding the microbiome, repairing the digestive system, and preventing recurrence.
Book your digestive health appointment here.
Always check in with your Naturopathic Doctor or other health care provider before starting any treatments or making changes to your healthcare plan.
About the author
Dr. Courtney Ranieri, ND is a board-licensed naturopathic doctor and the founder of Somewhere Health. She earned her Doctor of Naturopathic Medicine at the Canadian College of Naturopathic Medicine in Toronto and holds an Honours Bachelor of Science from the University of Western Ontario. Her clinical focus spans hormonal health, fertility, digestion, and women's health, with advanced training in pelvic floor therapy and integrative fertility care.
