MICROBIOTA - Intestinal microbes affect your mood. The gut nervous system is mostly independent of the central nervous system, but the vagus nerve connects them. Fat and thin people get different brain signals in response to sweet foods Stress affects motility, pH, immune response, bile, and mucous in the gut, and the gut microflora can cause stress in the brain. So eat at least a few teaspoons of yogurt every day, and fermented foods like sauerkraut. Much gut programming occurs when one is very young, so nursing and playing in the dirt are important to develop gut microbiota. Gut modulates brain development, and autistic children have more intestinal issues. Read more about the microbiome here.