Nevertheless cats are confirmed meat-eaters, they still eat young grass from time to time if they have an opportunity. Perhaps they get by this some extra minerals and vitamins. It's known that cooked food lacks one of B-vitamins that are contained in much in the grass. Most probably cats eat grass because they feel a need in fibrous pulp, which helps prevent constipation. Wild cats eat grass and innards of killed herbivores. Some domestic cats eat up young bean sprouts, houseplants, and flowers in a vase.
Cats suffering indigestion can eat great amount of grass whereupon to vomit it - that is they use grass as a natural emetic. Perhaps they do this when feel seek and intentionally arouse retching.
On the whole grass consumption doesn't harm a cat unless it wasn't treated with herbicides of cause. One can buy a packet of seeds and plant grass at home. This will allow to avoid poisoning and supply a cat living in a town with grass, especially those that are needed to be train not to eat house plants.
Translated by Tatiana Karpova (Moscow)
(MSU, Biology faculture, Dep. zoology and ecology).