Question: Why are some nutrients good while some are bad?

Sam Geen answered on 11 Nov 2020:

In general, there are two ways nutrients can be bad for you: if you have too much of it, or if they’re actually poisonous. Western diets can have a lot of calories and fat, and many of us (like me) work at a desk and don’t get exercise unless we play sports. There’s nothing wrong with fat, but too much of it will make us, well, you know. Some chemicals in food that are OK for humans can also be poisonous to other animals – the theobromine in chocolate is bad for cats, for example. Too much Vitamin A can also harm humans, although it’s hard to get this from a regular diet.