system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How pre-modern people's knew which foods were nutritious.

Edit: peoples*

By this I mean, how did people understand nutrition before vitamins and other nutrients were known and understood as we do today?
gpt
They didn't. 

They just knew the effects of eating certain plants and what certain plants would do based on taste and smell.

It's the main reason we have a sense of taste, to be able to tell if something has lots of sugar, acid, salt, etc.