Medieval people ate a largely vegetarian diet. Unlike modern vegetarians in the West, who usually choose vegetarianism primarily because they think it wrong to kill and eat animals, or else because they believe a vegetarian diet is healthier, medieval people for the most part did not have nearly as easy access to meat as we do.
Raising meat for food is always going to be more expensive than raising vegetables or grains, because you have to grow the food for the animals first, and a lot of the calories in that animal feed are going to be spent in having the animal grow and run around before you can eat it. Hunting animals that feed themselves in the wild solves part of this problem, but over-hunting can quickly reduce the number of potential game animals.
Hence for most medieval people for most of the time one's principal foods were bread and vegetables. In a recent post I discussed the fruits and vegetables medieval people grew. There were a lot of them, although of course the emphasis was on those that could be dried and stored (like peas and beans) or that would keep for a long time anyway (like onions and turnips). Lettuce could be eaten all summer long, but forget having a salad in the winter. The same was true of most fruits, though some, like apples, will keep at least a little while. They did not of course have the New World vegetables we now take for granted, most notably potatoes, tomatoes, corn, and winter squash.
Between the turnips, the radishes, the beans, the zucchini, the leeks, and the sauerkraut, there was at least some variety in the vegetables to be eaten. I've read that the single most common vegetable eaten in the US now is the potato, and that mostly eaten as French fries.
Still, medieval people liked their meat. Because most of the population was not vegetarian out of principle but rather because meat was hard to get, they ate it whenever they could. Indeed, meat was considered a health food. If someone was sick, they were given meat broth. The wealthy ate meat when they could get it, putting restrictions on hunting to keep the peasants from getting all the wild animals. Everyone ate pork in the fall, when the pigs, who had been running wild for months, were rounded up and slaughtered.
Even if mostly vegetarian, medieval people were not vegans. They were happy to have milk, butter, and especially cheese. Eggs were also fine. The most determinedly vegetarian people were monks and nuns, who gave up meat along with other pleasures of the flesh, in order to focus more on spiritual matters. They were still generally fine with eggs and cheese, and, depending on the monastic order, they might have fish once a week. If someone in the monastery was sick, they got beef broth.
© C. Dale Brittain 2021
For more on medieval food and other aspects of medieval social history, see my book Positively Medieval, available either as an ebook or a paperback, from Amazon and other book sellers.