This is a good video. It talks about how gut bacteria plays a roll in our health, and how we can eat certian foods to improve our gut bacteria. It also talks about taking pro-biotic supplements. But I am a firm believer if we can get them through natural foods it is much safer for us. Pro-biotics are proprietary, where as fermented foods are natural. It also discusses pre-biotic foods as well that we can eat.
Here is a Ted X talk how your belly controls your brain
Pre-biotics vs Pro-biotics https://yurielkaim.com/prebiotic-vs-probiotic/
Pre-biotic foods https://www.healthline.com/nutrition...rebiotic-foods