Do mushrooms make you poop?
Nope, for most people. A cup of mushrooms has very little fiber. They do carry mannitol, a sugar alcohol like the sorbitol in prunes, which can bother people with sensitive guts.
Did mushrooms make you go?
The meter says what should happen. Your bowels get a vote too.
Why it usually doesn't
Hardly any fiber
A cup of sliced raw mushrooms has under 1 g of fiber, a small fraction of the 22 to 34 g adults need a day.
But they carry mannitol
Monash University's FODMAP researchers list mushrooms among the vegetables richest in mannitol, a sugar alcohol the gut absorbs poorly. Sugar alcohols can pull water into the bowel.
How much, we don't know yet
Our data doesn't have a mannitol number for a cup of mushrooms, so the meter can't count it. People with IBS are the most likely to notice.
Sources: Monash University, Where FODMAPs are found; NIDDK, Eating, diet & nutrition for constipation; USDA FoodData Central.