Why Do Cats Eat Grass? The Science Behind This Strange Habit​

Many cat owners watch their pets eat grass and wonder about this peculiar behavior. I’ve seen my cats nibble on lawn blades many times, and they often throw up afterward. Most cats eat grass periodically for different reasons. They lack the enzymes needed to digest large amounts of grass. The science behind this behavior makes perfect sense. The grass contains folic acid that helps oxygen move through the bloodstream. Cats can’t digest fibrous grass like herbivores do, which explains why they often vomit it up or pass it unchanged through their stool. Let’s explore why cats eat grass, its safety implications, and the reasons behind this behavior even when they have quality food available. Veterinary science offers fascinating insights into this common feline habit.

The Instinct Behind Grass-Eating in Cats

Cats eating grass isn’t just some modern quirk—it’s a behavior deeply rooted in their history. Studies show this habit is incredibly common. About 71% of cats eat plants at least six times during their lives ^[1]. The numbers get even more interesting, with another study finding 89% of cats keep taking grass six or more times throughout their lifetime ^[2]. Scientists found the most convincing explanation by looking at wild carnivores. They believe cats developed this grass-eating behavior as a natural way to survive, helping them get rid of intestinal parasites by boosting their digestive tract’s muscle activity ^[3]. Wild carnivores’ droppings often contain parasites wrapped in plant material, which backs up this theory ^[4]. The fascinating part is that cats rarely look sick before they eat grass—91% seem completely healthy ^[1]. Young cats under 3 years old eat plants more often than older ones ^[5]. This might happen because younger animals’ immune systems aren’t as good at fighting off parasites ^[6]. Some experts think cats might be following their wild ancestors’ eating patterns without realizing it. Wild cats typically eat their prey whole, which means they also get the partially digested plants in their prey’s stomach ^[7]. This behavior sticks around in house cats today, even though they don’t have to worry about parasites as much. It’s just hardwired into their instincts. Research shows cats only throw up in about 27% of cases when they eat grass ^[5], which suggests that vomiting isn’t really the main reason they do it.

Health Effects of Grass-Eating

Cats eat grass not just by instinct – this behavior actually provides several clear health benefits. Grass works as a natural laxative because it contains lots of fiber ^[8]. The dietary fiber helps digestion by making muscles contract along the digestive tract ^[9]. Grass serves two purposes for cats with hairball problems. The grass helps them throw up hairballs that could make them uncomfortable ^[8]. The grass fibers also bind to hair in their digestive system and help it move through more easily ^[9]. Your cat’s grass contains an impressive mix of nutrients. The folic acid in grass helps produce hemoglobin and moves oxygen through the blood ^[8]. On top of that, it packs vitamins A, B, and D, along with magnesium, iron, and manganese ^[8]. The grass’s chlorophyll brings multiple benefits, giving your cat fresher breath ^[8]. Chlorophyll helped cats with anemia, infections, and skin conditions of all types before modern medicine came along ^[10]. All the same, letting your cat eat grass comes with some risks. Your cat’s body lacks enzymes to digest too much grass, which could make them throw up a lot ^[11]. Sometimes insoluble fiber builds up and might block their intestines ^[11]. More than that, grass blades can get stuck in their nose and make them sneeze ^[12]. This natural behavior stays safe and beneficial as long as your cat eats grass in moderation and the grass remains free of chemicals ^[13].

How to Manage or Support the Behavior Safely

Your cat’s grass-eating habit needs safe alternatives rather than restrictions. Growing “cat grass” indoors offers a safe option without pesticides or chemicals ^[14]. A mixture of wheat, oat, barley, or rye grasses works well and keeps your curious cat away from toxic houseplants ^[14]. Growing cat grass at home is easier than you might expect. The process is straightforward – plant the seeds in a deep pot with organic soil where sunlight reaches, keep the soil moist, and wait until it grows 2-3 inches tall ^[15]. A well-planted batch in a deep container lasts several months because roots establish firmly ^[14]. Cats that love their greens can safely enjoy these alternatives:

• Catnip (70% of cats respond to it) ^[16]
• Cat thyme ^[17]
• Basil ^[18]

Watchfulness is vital since many common houseplants like lilies, aloe vera, and philodendrons can harm your cat ^[2]. Call your veterinarian right away if you see excessive gagging, retching, heavy swallowing, or if your cat stops eating or drinking after eating grass ^[19]. Start with limited exposure to any new plant and watch your cat’s reaction before making it a permanent addition to their space ^[20].

Conclusion

The way cats eat grass shows a remarkable blend of instinct and adaptation. Our exploration has found that this odd behavior serves several vital purposes for our feline companions. This behavior isn’t a sign of illness but has deep roots in evolutionary history and likely emerged as a natural way to control parasites. On top of that, it offers health benefits beyond pure instinct. Grass works as a natural laxative, helps cats deal with hairballs, and gives them important nutrients like folic acid. In spite of that, cats should eat grass in moderation since they don’t have the right enzymes to digest large amounts of fiber. Your cat’s natural behavior doesn’t need discouragement. Providing safe options like indoor cat grass will give your feline friend a way to follow their instincts without exposure to harmful chemicals or toxic plants. Growing wheat, oat, barley, or rye grass indoors creates an ideal outlet for this natural behavior. The next time you see your cat nibbling on your lawn, note that they’re following ancient instincts that helped their wild ancestors thrive. This quirky habit might leave us with some cleanup duty, but it shows how our domestic friends stay connected to their evolutionary past. When we understand this behavior, we can better support our cats’ natural needs and keep them healthy.

References

[1] – https://www.hgtv.com/outdoors/flowers-and-plants/houseplants/7-plants-to-grow-for-cats [2] – https://michupet.com/collections/cat-grass-kit?srsltid=AfmBOooy2CHEwqTCM9_IoIkK38iOti67VixV2J5srdGdoQxmx8mf_LR- [3] – https://www.petscare.com/en-ca/news/post/why-cats-eat-grass [4] – https://www.dailypaws.com/why-do-cats-eat-grass-7491872 [5] – https://www.smithsonianmag.com/smart-news/researchers-figure-out-why-cats-eat-grass-180972885/ [6] – https://www.sciencedirect.com/science/article/abs/pii/S1558787825000784 [7] – https://westloopvet.com/blog/why-do-cats-eat-grass/ [8] – https://www.munchiecat.com/blogs/cat-behavior/cat-grass [9] – https://untamed.com/blogs/nutrition/why-do-cats-eat-grass [10] – https://www.petmd.com/cat/care/evr_ct_how-to-grow-cat-grass [11] – https://vcahospitals.com/know-your-pet/where-the-green-grass-grows-grass-treats-for-cats [12] – https://www.hillspet.com/cat-care/behavior-appearance/why-do-cats-eat-grass [13] – https://www.purina.com/articles/cat/health/digestion/why-cats-eat-grass-and-throw-up [14] – https://www.catster.com/nutrition/cat-grass-vs-catnip/ [15] – https://www.catonsvillecatclinic.com/holmes-corner/what-exactly-is-cat-grass/ [16] – https://www.foresthillvet.com.au/cats/catnip-vs-cat-grass-for-our-felines/ [17] – https://www.petguide.com/pets/blog/general-information/cat-grass-and-safe-alternatives-44470370 [18] – https://maven.pet/all-about-pets/pet-care/dog-diet/can-dogs-eat-vegetables/herbs-for-dogs-cats/?srsltid=AfmBOoqN3qZeEqGt6kbt4mqYaEV-9Zmnx5cIYcVb9xRJRAULxD170cEO [19] – https://uk.frontline.com/pet-advice/cats-and-grass [20] – https://www.chirpycats.com/cat-safe-cat-garden/