The Gut and Mood Connection
The bacteria in the human gut produce and influence neuroactive molecules, and they talk to the brain through the vagus nerve, the immune system and the bloodstream. Animal studies show clear effects on behaviour. Human evidence is real but much more mixed.
The human parallel
The feeling that your stomach knows something before you do. There is a genuine channel there — it is just not the simple one popular articles describe.
Why it matters
This is the area with the biggest gap between what headlines claim and what the evidence supports. Association is common. Causation in humans is rare.
What we can say
Each claim carries a confidence rating, a caveat, and the papers it rests on.