Food cravings and mood might be influenced by gut bacteria

ScienceDaily - Do gut bacteria rule our minds? In an ecosystem within us, microbes evolved to sway food choices


It seems this study is more of a theoretical postulation with a bit of evidence here and there that is consistent with it, yet the conclusion seems obvious: the bacteria that inhabit the human gut try to influence their host (the human) into eating more of whatever that bacteria likes to eat. The bacteria within the human gut are collectively called the "gut microbiome", and they are important in digestion and nutrient intake. Scientists theorize that it's through the vagus nerve, which connects the gut to the base of the brain, that microbes send signaling molecules and chemicals to the brain to try to influence it to take in more of the foodstuffs that the microbes consume. There is some evidence that intake of probiotics can influence human mood, and that some bacteria in the body can increase anxiety in mice. [This is a far cry from proof of microbiome influence, but it is at least consistent with it.] Furthermore, there is a good case to be made that bacteria that can influence the intake of their hosts would gain an evolutionary advantage. Interestingly, the rate of change in the microbiome is rapid; changes in its composition occur on a daily basis, based partially on what the human is eating. Thus humans have their own independent ability to influence their gut microbiome, and thus create either a virtuous or vicious circle of feedback.