Humans could theoretically survive on just potatoes and butter!
Potatoes are most often classified as a carbohydrate because the average potato has about 26 grams, yet if the skin is eaten, you are ingesting just about every vitamin and mineral necessary for survival!
An averaged sized potato of 150 grams has vitamin C, potassium, vitamin B6, thiamin, riboflavin, folate, niacin, magnesium, phosphorus, iron, and zinc. The only vitamins missing that humans need are vitamins A and D, yet if the potato is served with either butter or milk, both of those are fulfilled!
While nutritionists wouldn’t recommend taking on this diet, it is technically possible for survival.