SIBO March 12, 2019 Andreanna Rainville Small intestinal bowel overgrowth support SIBO (small intestinal bacterial overgrowth) is an "abnormally large numbers of bacteria present in the small intestine, leading to impairment of digestion and absorption" (Dr. Mark Pimentel, MD, of Cedars-Sinai). One common misconception is dysbiosis (overgrowth of bad bacteria and/or yeast with lack of good bacteria present) causes SIBO, but in fact, dysbiosis is the result of SIBO.