17. Gut health and ADHD

Note on the end: there is an abundance of(often funded) data showing that things do or do not cross the blood brain barrier, especially serotonin, although in my view it is poor research and inconclusive as there are animal studies showing otherwise. Leaky brain effect which everybody has to some extent likely exacerbates this phenomenon. Even just using logic, it doesn't make sense how the gut could have such impact on mental health and brain health without gut serotonin being able to cross BBB. With leaky brain in mind, it makes sense to assume this could be true just to try it out.