Their diet was similar to other European diets in the region until policies imposed on them by the English made the potato the only economically viable source of calories. The English essentially instituted a system in which the Irish served as sharecroppers producing major cash crops to benefit the English landowners. Because the majority of Irish land was owned by absentee English lords who demanded high profits, the Irish had to turn to less resource-intense means of calorie production than the grains and animals they had previously relied upon. When Europeans discovered the low-resource high-calorie potato, the English encouraged the Irish to rely on it for sustenance while other crops were sold for the benefits of landowners.

It should be mentioned that while a high proportion of the Irish did rely on the potato, it was not the only means of sustenance, and many people ate other foods found throughout the region.

So the reliance on the potato was something of an oddity in Irish history. For most of their history, their diet was quite similar to the diets found on the other British isles.