"You can see that maintaining a healthy gut is of much importance for the prevention and healing of many ailments and for general well-being. In maintaining a healthy gut and immune system, the gut flora has many functions, namely:
Proper nutrient uptake;
Protection against pathogens, viruses and opportunistic bacteria;
Nutrient creation (e.g.: Biotin, vitamin K2, butyric acid, …);
Preventing systemic and gut inflammation;
Proper metabolism and weight regulation;"
You And Your Gut Flora | Paleo Diet Lifestyle