Sozai Saishuka no Isekai Ryokouki - Chapter 5

… In a medieval themed fantasy world, I would not touch food that I haven’t prepared myself.

From growing the grains to the final bread. Or from growing the grains to feeding the livestock to the meat / milk and then the meal.
Why?

1. No refrigeration (e.g. untreated milk goes bad within hours without it)
2. No knowledge about hygiene there. … You don’t want to know.
3. Lack of concern. Eating your fill was a rare occasion, so people weren’t picky what they were eating. People were eating food with mold on it on regular basis. Among other things they didn’t threw out those “nice large” wheat grains. Known as Mutterkorn in German. Which was mistaken for large grains. Claviceps purpurea is the latin name of the fungus that does that. And is highly toxic.
4. And don’t get me started on water. The reason most people drank beer (that included weened toddlers) is that you had a high chance of dieing of diarrhea when drinking water. They didn’t connect that the water for beer production was boiled. Sidenote: That beer had very little alcohol content. About 1/10 of a normal beer today.
5. And then there was meddling with food. One of the worst offenders was England in Victorian era just before industrialisation. Where bread could have as much as 75% plaster of paris. And a lot of other nasty stuff. And yes, that’s basically a plaster brick with minor contents of flour mixed in.

Sooo … knowing this very abbreviated list would you still eat food you don’t know every detail of? If yes, wait till you learn the whole truth.