Splendid is the grass: Why cats graze
To supplement their diet
Grass juice contains folic acid, a vitamin that supports cats’ growth and helps increase oxygen levels in their blood. If your cat is grazing, it may be because he or she is battling a dietary deficiency and is in search of this vitamin boost.
For natural laxative benefits
Eating grass helps your cat have regular bowel movements, something that's especially important for digestive tracts sometimes clogged by fur. While broad grasses seem to have a laxative effect, narrow grasses are suspected to help a cat settle an upset stomach.
It relieves an upset stomach
You may notice that your cat vomits shortly after eating grass—he or she is actually doing this on purpose. Cats don’t have the necessary enzymes to digest a large amount of grass, which is why it can make them sick. But in the process of throwing up, your cat also clears his stomach of fur, feathers, parasites or bones, which can irritate the digestive tract or even cause more lasting illness.
When your cat eats grass, he will typically self-regulate the amount. If the grass has been treated with pesticides or fertilizers, keep your cat away from it—and consider growing grass indoors for your cat. Specialty retailers sell wheat or oat grass kits designed for in-home use.
If your cat begins to eat large amounts of grass or wants to eat grass every day, consult your veterinarian.