Liver (food)

Liver is a food which humans can eat. It is offal, which means it is not muscle tissue. The flavor might be strong for some people, so it might be slightly over-seasoned.
The liver stores vitamin A and other things. Vitamin A is used by the body to make rhodopsin, a molecule which absorbs light. It is needed for low-level vision and colour vision. Vitamin A also plays a key role in gene transcription. It also plays a key role in the immune system.
Once made, vitamin A cannot be broken down by the body, and it is not easily excreted. So it tends to build up in the liver if too much is eaten. Vitamin A is fat-soluble, so getting rid of any excess taken in through diet takes much longer than with water-soluble B vitamins and vitamin C. This allows for toxic levels of vitamin A to build up.
It is not good to eat cooked liver too often. Eating lots of liver, especially from carnivorous animals, will give a person too much vitamin A.