This is rather interesting to me, as I have gut issues where I should be limiting my consumption of red meat. Red meat, specifically beef, in excess gives me rather uncomfortable toilet visits, however completely refraining from any at all causes flare ups in my mental conditions (namely, my depression and CPTSD symptoms are somewhat more exaggerated). It's at this point where I would crave something like a burger, almost like an addiction that somehow lay dormant until that moment, and my mood is lifted for some time afterwards.

I'm not within the field of science, however I have been noting how my diet affects my gut and mind for many years now, and that's just what I've noticed. It makes sense to me for a study to prove some correlation as well between the gut and brain.