Your cat might be a finicky eater. She turns up her nose at all but the finest of foods and will only drink water out of a spotlessly clean bowl. But if you let her outside, she starts chowing down on grass. Why would your persnickety pet nibble on the lawn?

No one knows for sure why some cats enjoy dining on the occasional blade of grass, but there are several theories about this feline behavior.

Natural laxative

One popular belief is that grass helps move unsavory things through a cat's system, adding fiber and bulk to its diet, says Animal Planet. Acting like a natural laxative, grass pushes things more easily out the other end. This might include worms or hair that have made it deep into the digestive tract, too far to be vomited out.

Stomach helper

cat with mouth open Your cat might eat grass to help him vomit up something unsavory. (Photo: Suzanne Tucker/Shutterstock)

Another theory is that grass-eaters are dealing with some sort of gastrointestinal upset. Eating grass may act as a sort of regurgitation tool, helping cats get rid of hair that they swallowed through grooming or feathers and bones from prey she might have captured, according to PetMD.

Instinctively, cats know that eating the grass will help them vomit the offending material. It's because their digestive systems don't have the enzymes they need to digest grass. So, when they throw up the grass, ideally they also rid themselves of whatever else was causing gastric distress.

Other GI issues

Similarly, eating grass may help a cat dealing with an underlying gastrointestinal disease, such as inflammatory bowel disease or food allergies, writes veterinarian Dr. Wailani Sung in VetStreet.

"For a cat, eating grass may be her way of trying to alleviate any discomfort she may feel," Sung says. "The grass may either provide some material to fill up the stomach or, in some cases, induce vomiting to try to eliminate something in the stomach that is making the cat feel ill."

A nutritional boost

Grass and other plants can be rich in folic acid, a B vitamin that's important for your cat's health. Animal Planet points out that folic acid, which is also found in a mother cat's milk, helps produce oxygen in the blood. Without enough folic acid, a cat can develop anemia, which can affect its growth.

Experts don't know how a cat would instinctively know that he is lacking in this nutrient. But there could be an inner signal pushing them to go for a graze.

Sign of stress

cat nibbling kitty greens If your cat nibbles house plants or your grass is chemically treated, consider growing her some 'kitty greens.' (Photo: AllaSaa/Shutterstock)

Constantly eating grass may be a sign of displacement behavior, says Sung, where a cat is trying to cope with stress.

"What may cause your cat to be stressed? She may be genetically predisposed to experiencing anxiety, but in many cases a lack of early socialization or exposure to early negative experiences can also contribute to the development of an anxiety disorder," Sung say. "To cope, some cats may exhibit over-grooming or excessive vocalization when they are anxious, while other cats may try to engage in a different activity to soothe themselves, such as finding something to chew on. Indoor-only cats may not have access to grass so they may chew on household plants instead."

If your cat starts chewing on your plants, make sure they aren't toxic. And if your cat is allowed outdoors and fancies the occasional nibble on grass, make sure your grass isn't chemically treated.

Cat behaviorist Pam Johnson-Bennett suggests growing a pot of safe grass for your pet using rye, wheat or oat seeds or purchasing a "kitty greens" kit at a pet store or online.

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.

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