This is probably one of the best reads on the gut microbiome I've come across as it takes a fairly complex topic and breaks it down (no pun intended!) into simple concepts that are easy to understand. You will have a much better understanding of how the food you eat impacts your body's health through your gut. Highly recommended!!
"There is abundant medical evidence that diet greatly influences health, and new science is showing us why this is so. It is also showing us that advocates of trendy paleo and vegan diets are missing the big picture of how our omnivorous digestive system works."