Potatoes contain starch. When uncooked, they are hard on your digestive system and can cause bloating. They are rich in solanine, a toxic toxin that can lead to nausea and headache. That's why you need to cook them.
It may seem absurd, but getting poisoned by consuming toxic foods is much easier than one might think. Potatoes, red beans, fresh milk: here are the foods that must always be cooked before being served.