Inulin, a “stealth fiber” increasingly added to processed foods, can cause stomach pains for people who might not realize they’re eating too much of it, registered dietitian Joanne Slavin, who recently led a study on it, told Reuters. The additive can be found in chocolate bars, drinks and snacks; while this carbohydrate fiber occurs naturally in foods like bananas and onions, it is also extracted for industrial use. Most carbohydrates are broken down in the small intestine and turned into fuel, this one passes through to the colon, stimulating “good bacteria” production and becoming fermented there, sometimes causing gas, bloating, flatulence and diarrhea. In a study spurred by its growing popularity, Slavin looked at 26 healthy men and women aged 18 to 60. Serving them inulin mixed into orange juice, or a placebo, they found that healthy people can generally tolerate up to 10 grams of native inulin, and 5 grams of “sweet” inulin (which causes faster fermentation in the gut) per day.