I was told in the hospital not to eat tomatoes nor mushroom when I got crohn's disease, they explained why but I forgot the part about the tomatoes. The mushrooms is because they are one of the most indigestible food substances people eat, you gain almost no nutritious value form them.
I looked up why they told me not to eat tomatoes once but I can only find studies that say tomatoes are a good anti-inflammatory because of the high amount of lycopene in them (which gives them their red color). Studies are only paid to find the good stuff in food substances though, they're not paid to tell tomatoes are bad for you, you don't get another grant from the food industry or from the probiotic industry if you say something doesn't work, or worse, it makes people sick, that's your last grant you'll get. So I avoid tomatoes, I don't like them really, same with spaghetti sauce.