The Indians of México and the what is now the southwestern US ate the “CBS diet” (corn, beans, and squash), which gives a complete amino acid combination for making all the protein the body needs. It is a good, staple diet.
The peppers provide vitamin C and other useful nutrients, some of which have antimocrobial properties.
They were able to preserve food by drying it.
Good Méxican food is great. Of course, every developed culture has some good food, but this diet was available generally, and was probably preferable to what people in some other places were eating.
Rice and beans provide protein and niacin. Another Mexican staple.