Why do cats eat grass, and is it good for them?

Written by Napo HQ
Reviewed by Dr Louisa Lane
14th Jul 2022
7 mins read
Not all cats eat grass, but it's considered a normal and common behaviour. There's a few theories why they do it.
Cats are “obligate carnivores”, or “true carnivores”. That means they need a diet of meat to survive, and don’t need to eat plants in their diet. However, most cats can be found eating grass from time to time.
But if they don’t need it for nutrition, why do cats eat grass? And should you be concerned if you notice your cat starting to graze on the lawn?
Here’s everything you need to know about why cats eat grass. And don’t worry, it’s not a sign that they’re sick!

Why do cats eat grass?

Not all cats eat grass, but it is considered a normal and common behaviour if your cat does.
At the moment, there isn’t one definite reason why cats eat grass. There isn’t enough research or scientific evidence for anyone to know exactly why cats graze. However, there are several theories that might explain why your cat has a habit of munching on plants.

It can help to aid digestion

Grass is full of fibre, which benefits your cat’s digestive system and helps to keep their bowel movements regular.
Plus, a cat isn’t evolved to digest plants effectively, so grass doesn’t break down a lot in their digestive system. That means any grass they eat passes through them, and along the way, it’s thought to help clean out their gut.
It has been speculated that the digestive benefits of grass mean that it can help to clear out hairballs. However, short-haired and long-haired cats show similar grazing behaviour, so it’s not clear whether there’s much truth to this theory.
If you are worried that your cat might have a hairball stuck inside them, you should contact your vet rather than feed them grass.

It was thought to get rid of parasites

As well as cleaning out the gut, it had been theorised that eating grass could help to remove parasites, like worms, from your cat's digestive tract. However, this is unlikely to be true.
The only reliable way to make sure your cat is free from parasites is to provide them with regular worming treatment that has been formulated and prescribed by a vet.

It can provide a nutritional boost

Although we might not think so, grass can have some nutritional value. It’s certainly full of fibre, and it contains some vitamins and minerals too, including folic acid which is a vital part of a cat’s diet.
Grass also contains chlorophyll, which is what makes the plant green. Chlorophyll is said to have a number of health benefits, for humans and cats. So it’s possible that one reason why cats eat grass is to top up their nutrients.

They just enjoy doing it

Another reason why cats eat grass is that it is probably just a tasty and enjoyable thing for them to do. We humans love to snack on things, after all. Plus, chewing helps work the jaw muscles. So your cat could be eating grass because it’s a pleasant pastime.
Even if it has no real benefit to their body, eating grass is a natural and normal cat behaviour. If you can provide some cat-safe grass for your cat to graze on, you’ll be providing them with enrichment and the ability to demonstrate normal behaviour.

Do cats eat grass because they’re sick?

Although there isn’t a lot of research, studies have indicated that cats don’t eat grass because they’re sick. Nor do they eat grass to make themselves vomit.
That being said, it isn’t uncommon for cats to regurgitate grass, and any other material they can’t digest. This can sometimes look like sick, but it isn’t usually anything to worry about unless your cat is doing it regularly or if there is blood in their vomit or regurgitations.
As far as anyone can tell, cats eat grass because it’s just a normal behaviour for them, it’s enjoyable, and it could be helping their gut.

Are there times when I shouldn’t let my cat eat grass?

Although eating grass is a fairly common and normal behaviour for your cat, you shouldn’t always let them do it. Here’s a quick low down of when it isn’t safe to let your cat eat grass.

Be aware of harmful chemicals

You shouldn’t let your cat eat any grass they find. Most lawns outside are treated with pesticides, herbicides, fertilisers, and other chemicals that are potentially toxic to your cat.
You shouldn’t let your cat eat any grass that’s been treated with these chemicals because it could make them sick. If you’re not sure if the grass has been treated, the safest thing to do is to try and prevent your cat from eating it. However, it can be hard to know if your cat is eating grass outside when they roam, let alone stop them.
Instead, you could provide grass in your own home or garden that you know hasn’t been treated, to give them a safe and easy-to-access option they will hopefully choose to use instead.

Make sure they aren’t eating toxic plants

Grass isn’t the only plant your cat might munch from time to time. The problem is, a lot of the plants in our homes and gardens are toxic to cats. Make sure all the plants in your home and garden are safe for cats, or that they’re out of reach of your cat so they can't nibble on them.

How to let your cat eat grass safely

In an ideal world, you would be able to stop your cat eating grass outside, just in case it’s contaminated with chemicals. But given it’s near impossible to know what your cat gets up to outdoors, you can instead provide a safe alternative and grow grass in your home that's safe to eat and easy to reach. You can do this by growing some cat grass.

What is cat grass?

Cat grass isn’t one type of grass, it’s commonly a mix of wheat grass, oat, barley, and rye.
Barley is a good option to grow at home because it grows quickly. Rye is a robust grass that can survive being climbed on or rolled on by your cat. Wheat grass is packed with more chlorophyll, vitamins, and minerals than other grasses. It could potentially be more nutritious for your cat to eat. (It’s the same reason it ends up in a lot of human health foods!) Meanwhile, oat grass is believed to be the most flavourful of all the different catgrasses.
It doesn’t matter whether you grow just one of these grasses or a mixture of them. They are all safe for your cat to eat, as long as they aren’t treated with chemicals.

How to get cat grass for your home

If you want to provide some safe cat grass for your cat, you have a choice between buying cat grass or growing your own. If you buy cat grass, remember to make sure it’s organic so it hasn’t been treated with pesticides and other chemicals.
Alternatively, you can buy cat grass seeds and grow the grass yourself. This way, you can control how much grass you have, and make sure it is chemical-free and safe for your cat. Grass doesn’t take a long time to grow either, and it’s very easy to grow. So you don't need a green thumb or a big commitment to grow your own.

Should I be worried that my cat eats grass?

Although eating grass is normal for cats, there are times where it could be a cause for concern.
If your cat has never eaten grass before and has suddenly developed the behaviour, it’s a good idea to take them to the vet for a check-up. That way, your vet can make sure there are no underlying health problems that have caused your cat to start grazing.
Secondly, if your cat has started eating more grass than is normal for them, or is regularly being sick, you should take them for a check-up. Again, this is because your cat could be unwell which has prompted the change in their behaviour.
You should always call your vet for advice if you are ever worried about your cat and any changes in their behaviour. If have cat insurance with Napo, you get free and unlimited video calls with vets, whenever you need them.

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