A new theory suggests that acid reflux is caused by carbohydrate malabsorption, small intestinal bacterial overgrowth (SIBO) and microbe-induced gas pressure. The pressure drives acid reflux much like dropping a Mentos in a bottle of coke. Difficult-to-digest Carbohydrates lactose, fructose, resistant starch, fiber and sugar alcohols are most likely to cause malabsorption and symptoms of SIBO-related conditions such as GERD and IBS. A novel calculation called fermentation potential (FP) can measure the gut symptom potential of any food. The low FP approach was successfully tested in a small clinical study in the Boston area.