Gut-brain connection

Mental health is strongly connected to our guts. Our guts are our "second brain". Each of us literally has two brains — the familiar one encased in our skulls and our second brain, the gut. They’re kind of like Siamese twins, completely interconnected; when one gets upset, the other does, too. This is exactly why when we are nervous or afraid, we may experience "butterflies" in our stomach, intestinal cramping, or nausea. I believe you cannot separate the two, it is near impossible.

Anxiety and Depression are connected to gut health. Up to 90% of serotonin is actually produced in the gut (as opposed to the brain). How's that for a gut-brain connection?