I suffered from chronic constipation as a child but then switched to regular D as a teen and in my early 20s.
Over the past 2 years I've been sorting out my food intolerances (onion, garlic, peppers, sugars, casein/lactose & gluten) and when I would eat a big batch of something my body didn't like I'd get D for days - french onion soup was what tipped...