Lettuce

It adds very little nutrition and is mostly an ingredient that gives the recipe the look of variety.

Lettuce is a leafy green vegetable that is mostly water, with small amounts of vitamin K and fiber. In cat food it appears dried and in very small amounts. We found no FDA or Merck guidance on lettuce in cat food specifically. If your cat has a medical condition, your veterinarian can tell you whether any ingredient in its food matters for its care.

In cat food, lettuce is a dried leafy green added in small amounts, usually in recipes with a long list of vegetables. Its nutrient contribution is minor because fresh lettuce is mostly water. It works mainly as a plant ingredient that appeals to owners.

Many cats can nibble plain lettuce without problems, and some like its crunch. It offers water and fiber but little nutrition for an obligate carnivore, as Cornell's Feline Health Center describes cats. Treats of any kind should stay a small part of the diet. Wash it well and skip dressings or onion-containing salad mixes.

Source: vet.cornell.edu

Nobody knows for sure why cats eat grass and leafy plants. Common ideas are that the fiber helps bring up hair or that cats like the texture. Cats do not need plant matter for nutrition, since they rely on nutrients found in animal products. A cat that suddenly eats a lot of plants or vomits often should see a veterinarian.

Source: vet.cornell.edu

Pettings gives lettuce 3 out of 5 and lists it as a fruit or vegetable ingredient. It appears on 1 of the 149 dry cat foods we list. The page notes lettuce is mostly water with small amounts of vitamin K and fiber. Each food's page shows how it scores overall.