With the addition of milk or buttermilk potatoes form a scientifically satisfactory diet, as the physique of the pre-famine Irish proved. Arthur Young contrasted the Irishman’s potato diet favorably with the contemporary English labourer’s bread and cheese. The Irish, he wrote, “have a bellyful . . . I will not assert that potatoes are a better food than bread and cheese but I have no doubt of a bellyful of the one being much better than half a bellyful of the other.”

— Cecil Woodham-Smith, The Great Hunger: Ireland 1845-1849