Why cats eat grass

We have all seen cats eat grass...but why do they do it? Listed below are some suggestions that have been put forward over the years:

* Cats use grass as a laxative to enable them to pass hairballs lodged in their intestines.
* Cats eat grass to make them vomit up hairballs.
* Cats eat grass because they are feeling sick and this makes them vomit, getting rid of poisons.
* Cats eat grass to relieve inflammation of their throats.
* Cats eat grass to relieve stomach ache.
* Cats eat grass to add roughage to their diets.