How are those poisonous nuts called, which cannot be eaten a lot?

The Brazilian ones. They are not poisonous, but contain a bit of radon.

HHH: How many can they be?

A couple of pieces a day.

What if I eat a lot?

You will not be poisoned. In order to have a noticeable effect, they need to be turned around a lot every day.

HH: And what will be the noticeable effect?

Wow, you will get fat.