Fish Bad, Sugar Good and Other Medieval Ideas About Food

> In thirteenth-century England, Christians were expected to avoid meat every Wednesday, Friday and Saturday during Lent (when eggs and dairy products were also forbidden), Advent and on some saints’ days (or the eves of their feasts)

Every person (back then) could observe farm animals had sex. Since no one had seen fish having sex, it was believed that fish spawned spontaneously from rivers/lakes/oceans and therefore were free from the animal version of "original sin". That's why so much effort was put into catching and preserving fish.

Source:

https://www.amazon.com/Cod-Biography-Fish-Changed-World-eboo...

Also history of food:

https://www.amazon.com/Salt-World-History-Mark-Kurlansky-ebo...

The author has a fascination with Basques & Basque history. Or maybe they really had a large influence in fishing and trans-Atlantic navigation. And that maybe they discovered the huge cod banks by Newfoundland before John Cabot did.

https://en.wikipedia.org/wiki/John_Cabot

Medieval people were not stupid. They observed that pickled vegetables preserved the veggies for months. And they observed that people who ate pickled vegetables got scurvy (vitamin C deficiency disease) at a much lower rate. The recipes didn't travel too far, so while sauerkraut and kimchi are both pickled cabbage, with different spices they are wildly different.

It's fascinating how closely this parallels Chinese traditional medicine, where foods are classified as "heaty" or "cooling" and health conditions can be both caused and treated by an excess of one or the other.

https://en.wikipedia.org/wiki/Chinese_food_therapy

> "Fish Bad, Sugar Good"

> "Similarly, some fruits were safer than others: citrus fruits improved digestion, especially in hot weather, while raisins were good for the stomach, lungs and liver. And nuts were nutritious and good for the brain."

My impression is that refined sugar was extremely rare in medieval times and into the renaissance. But everybody loved raisins, and they were used extensively, even though they were usually imported from Italy and other Mediterranean regions. Various forms of raisin bread (often with dried figs, citrus peels, and currants,) were the definitive medieval festival/feast-day food. Their distant descendants are the stollen, panettone, etc., still popular as holiday treats in Europe.

Certain regions of medieval Germany (and presumably France) grew grapes but had to resort to ingenious methods to dry them into raisins: https://www.culina-vetus.de/2026/08/27/raisins-in-a-cold-cli...

I am sure that in the past, good or bad food was more about conservation and food borne diseases than it was about nutrition. At least, that's the attitude that would make the most sense. That would explain sugar good / fish bad. There is probably a political aspect too, local food is seen as better than the rival neighbor food.

The modern, first world attitude must be very unusual towards history. We basically solved conservation and food born diseases are now uncommon and mostly treatable, and we have an abundance of anything, so nutrition is the only thing that remains when discussing healthy food.

What didn't change is the made up theories surrounding food. Despite all our science, we still have a lot of these today, in some for or another.

This article seems unusually misrepresenting of the theory of humours, which was prevalent in medieval Europe, at least in the catholic parts. This theory stated that no food was explicitly bad or good; rather, you should eat food that is suitable for your temperament. In that sense, they did not believe any food is necessarily (at least in terms of the humours) unhealthy; rather, it may be unsuitable or suitable for your temperament and the balance of humours within you. The hesistance of wet was mostly of its association with diseases; but it was recommended to cholerics, whose temperament needed to be balanced with it. In a sense, it sometimes produces better results (by chance) than modern dietary practices which often held up some types of (seemingly innocent food; like animal fats) to be categorically unhealthy.

> According to Galen, food “is probably the most important of all medical subjects,”

Just remember that in medieval times growing food was the job of the majority of men. Men also were the people most likely to be educated and actually write and talk about things and so food would be something on their mind. They would be growing it and thus writing about it. contrary to modern ideas men actually appeared to have done a lot of cooking: women were not common in the army (different cultures had different perspectives on women with the army. Some would have more than others, but in any case, you would have men as the vast majority) so men would have had to do at least some cooking. Even your common peasant farmer man would likely spend a significant amount of time out in the field at lunchtime where the women are not around and so would have to fend for themselves for their lunch.

I bring the book up to point out that no one has ever asked what women were doing and what was important. This is something historians are looking at now when trying to piece together what must have been happening. As a general rule, you can say that every woman was spending the vast majority of their working hours making thread so they could have clothes, but since women were rarely the ones who were writing, we have almost no historical record of clothing. What we do have is often from tailors who would be a male and thus something that occasionally a man would write about.

> lettuce was dangerous because it was so cold and moist

Joke's on us, I guess.

https://www.fda.gov/food/outbreaks-foodborne-illness/investi...

Considering how fast fish without refrigeration would spoil back then, the rarity of access to sugar and the need for energy dense foods, "fish bad, sugar good" makes perfect sense.

The article kind of misses the forest for the trees: just as today, diet was associated with various conflicting theories and advice - some reasonable, some pure fabrication. In absence of much hard evidence food becomes a playing field for "systems" that assign values to foodstuffs. Also, obviously, sugar played a different role in societies in which the calorie requirements of physical labour were a much bigger challenge than obesity.

Also: "beans, which were thought to cause flatulence"? I'm pretty sure that bit is factual.

Considering how quickly poultry and fish go bad, they weren't entirely wrong.

You can base an entire food brand on that article. The Tik Tok channel alone would be massive.

It's interesting how some of these came to the right conclusions (given sanitary standards at the time) but for entirely the wrong reasons. A lot of the food that was unhealthy was food that could go bad quickly or carry illnesses

I enjoyed reading this, I found the article equally interesting and amusing. As a curiosity — it says that beef was cheap and suitable for manual labourers, and salmon was a staple of the monastic diet. How did they end up being among the most expensive in their respective groups?

Is this article really about medieval? Sounds very familiar to todays food culture. Everyone makes claims without having a solid justification, yet the observations indicate that it is true.

Nothing has changed, but nowadays we have papers that document observations and sell their theory as the truth; in the past, we had cookbooks.