Dairy, in general

 

Pros: 
tons of nutrients, especially in raw milk, delicious, nomads who rely on it are generally pretty healthy
Cons: 
Large % of the population is lactose intolerant= damage to digestive system for those who are lactose intolerant, cocktail of hormones meant for growing cow, betacellulin = hormone tied to cancers, casein shown to be addictive in some studies = esp. dangerous when combined with sugar like in milk chocolate