Why do cats eat grass?

Cats don’t eat grass as a source of nutrients. For them eating grass has a purely mechanical function. Ingested blades of grass trigger regurgitation of indigestible or hard to digest matter, like the cats’ own hair swallowed during grooming, or fur and bones of prey. Expelling this matter through regurgitation, similar to birds of prey, is safer than allowing it to pass through the digestive tract where it could possibly cause a blockage.

Provide indoor cats with potted grass at all time, as they may otherwise chew on houseplants. Discourage your cats from eating grass right after eating a meal, however, as they may unintentionally regurgitate their dinner.