Is Your Guinea Pig’s Diet Providing the Right Nutrients?

Updated Aug. 11, 2022

Feeding your pets seems like such a simple process: buy a bag of food and feed it to your pet, right? But do you really know what a guinea pig can eat? It is a lot more complicated than just buying a bag of food.

Guinea pigs have some very specific dietary needs, and these may differ from their dietary “wants.” Add this to the fact that some guinea pig foods favor taste appeal over good nutrition, which makes it difficult for pet parents to know if their pets are getting the nutrition they need to thrive.

All of that being said, feeding a guinea pig doesn’t have to be hard; however, it isn’t quite as easy as picking up a bag of guinea pig food and pouring some into the bowl, either.

Let’s take some of the mystery out of making sure your companion is getting everything necessary for good health!

The “Natural” Guinea Pig Diet

Understanding what guinea pigs used to eat in the wild is the cornerstone of figuring out what their diet should be today.

Guinea pigs are designed to be herbivores, which means their biology has been adapted over the years to strictly digest plant materials and fibers. As natives of the Andes of South America, wild guinea pigs ate primarily forage—grasses and plant materials that are low in nutrition and high in fiber. 

When we domesticated the guinea pig, we also adjusted their diet to include nutrient-rich foods, such as yogurt drops, dried nuts and fruits, commercial guinea pig pellets and sweet and sugary treats.

Their bodies have not adapted quickly to these changes in diet, so the foods we often offer them—although well-loved by the guinea pig with a sweet tooth—are likely to cause disease.

Additionally, guinea pig teeth continue to grow throughout their lives, and if they are not properly worn, it can cause massive (and even fatal) health problems.

What Can I Feed My Guinea Pig Daily?

In reality, guinea pig diets are pretty simple. In fact, if I had to pick one item for a guinea pig to eat, it would be hay—lots and lots of hay!

Did you know that hay comes in different flavors and varieties? And, each of these different types of hay has a different nutrient profile. By balancing out differing types of hay, it is possible to create a balanced diet for a guinea pig as well as provide some interesting variety of tastes.

A few types of hay that you can offer to your guinea pig include timothy (e.g., Oxbow western timothy hay), orchard grass (e.g., Oxbow western timothy and orchard hay or Oxbow orchard grass hay), barley hay, bromegrass, bluegrass, oats (e.g., Oxbow oat hay), wheat and fescue. In general, the only hay I routinely recommend avoiding for most animals is alfalfa. It is quite high in calcium and can cause stones in some animals.

It is quite possible for guinea pigs to eat a well-balanced and complete diet alone through a variety of hays. Hay also has the additional advantage of being a food that the guinea pig intestinal tract is designed to process—and it even helps keep the teeth worn down in a proper fashion.

If you purchase a sun-dried hay, there is the added benefit that it may contain more vitamin D as well.

Fresh Vegetables in a Guinea Pig’s Diet

Guinea pigs benefit tremendously from fresh vegetables. Notice I’m not saying fresh fruit, which is high in sugar, and we already know that most pigs have a sweet tooth.

I recommend about a cup of vegetables per guinea pig per day. If you haven’t been feeding any, you might need to start slowly and work up because we certainly don’t want to cause an upset tummy with a diet change—but a cup a day is a good goal.

You can also use vegetables to provide vitamin C and other nutrients that are not found in high amounts in hay to help round out your guinea pig’s diet while also continuing to help grind those teeth down.

Some of the best vegetables for guinea pigs include green or red peppers, parsley, romaine lettuce (not iceberg, which is not very nutrient-rich), cantaloupe, dandelion greens, corn husks and silk, cilantro and carrots. Be creative and try different varieties to see what your pig likes the best! But with nutrition, the more variety, the merrier.

Just make sure to discuss the introduction of new foods and portions sizes with your veterinarian beforehand.

Vitamin C Is an Essential Part of a Guinea Pig’s Diet

Guinea pigs have a unique metabolism that does not allow them to create their own vitamin C; they rely on what they eat to provide them enough this essential vitamin—which is about 10-30 mg/kg/day.

There are a number of vitamin C supplements on the market, but I prefer to supplement it the natural way—through their diet. Some fresh veggies that are rich in vitamin C include beet greens, alfalfa sprouts, broccoli, brussels sprouts, cauliflower, swiss chard, dill and parsley—just to name a few.

If you do feel the need to add supplements to your guinea pig’s diet, it is best to talk to your veterinarian to find the best option for your guinea pig.

I don’t recommend adding the vitamin C to their water because some pigs do not like the taste and will avoid drinking it, which causes them to become dehydrated. Offering some vitamin C drops or children’s tablets may be the best alternative in that instance, but you should talk to your veterinarian to find the best option and dosage for your guinea pig.

Don’t Forget About Fresh Water

Guinea pigs need lots and lots of fresh water. Some will drink best from a sipper bottle—like the Kaytee chew-proof small animal water bottle—while others simply plug up the sipper with hay and do better from a bowl—like the Ethical Pet stoneware crock cat dish. No matter the vessel you choose, fresh water should be readily available 24 hours a day.

Commercial Guinea Pig Pellet Food

In reality, guinea pig pellets are not a necessary or required part of their regular diet. In fact, guinea pigs that overeat pellets can develop obesity as well as dental disease, so the amounts should be restricted.

Additionally, guinea pig pellets are often made from alfalfa, which is often too high in calcium and may cause bladder stones.

If you choose to feed your guinea pig pellets, limiting the amount to 1 tablespoon per day might help to round out the diet without causing harm. You will want a timothy-based pellet with no added fruits or nuts that is formulated with a stabilized vitamin C. However, pellet food is not needed if you are careful to round out the remainder of the diet.

Guinea pigs do best on a wide variety of foods, including multiple types of grass hays, several different vegetables (preferably that contain vitamin C) and lots of fresh water. So, head out to the grocery store and see what special vegetable treat your piggy can enjoy for dinner tonight!

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Sandra C. Mitchell, DVM, DABVP


Sandra C. Mitchell, DVM, DABVP


Sandra Mitchell is a 1995 graduate of the New York State College of Veterinary Medicine. Since graduation, she has worked in many fields...

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