Why the ancient Egyptians were the healthiest people in the world

I will describe some of their habits: every month for three successive days they purge themselves, for their health's sake, with emetics and clysters, in the belief that all diseases come from the food a man eats; and it is a fact - even apart from this precaution - that next to the Libyans they are the healthiest people in the world.

Herodotus - Histories (II, 77)