For the Irish had discovered that a diet of potatoes supplemented with cow’s milk was nutritionally complete. In addition to energy in the form of carbohydrates, potatoes supplied considerable amounts of protein and vitamins B and C (the spud would eventually put an end to scurvy in Europe); all that was missing was vitamin A, and that a bit of milk could make up. (So it turns out that mashed potatoes are not only the ultimate comfort food but all a body really needs.)
