The best food for guinea pigs is unlimited grass hay, with a small daily serving of plain pellets and fresh vegetables. Hay should make up most of the diet. Guinea pigs also cannot make their own vitamin C, so they need a daily source of it from vegetables or fortified pellets.
The Four Parts of a Healthy Guinea Pig Diet
1. Hay (the Foundation)
Fresh grass hay should be available 24/7. Timothy and orchard grass are the usual choices for adults. Hay keeps the gut moving and wears down teeth that never stop growing. See our full guide to hay for guinea pigs.
2. Pellets (Measured Daily)
Choose a plain, timothy-based pellet made for guinea pigs, ideally one fortified with stabilized vitamin C. Avoid mixes with seeds, nuts, dried fruit, or colorful bits, because guinea pigs pick out the sugary pieces and skip the rest. A common guideline for an adult is about 1/8 cup per day, but ask your vet what is right for your pig’s size and age.
3. Fresh Vegetables (Daily)
Offer roughly a cup of mixed fresh vegetables per guinea pig each day, spread across the day if you can. Good everyday choices include:
- Romaine and red or green leaf lettuce (not iceberg, which has little nutrition)
- Bell peppers, a top vitamin C source
- Cilantro, parsley, and other leafy herbs
- Cucumber and zucchini
- Small amounts of carrot tops and dandelion greens
Higher-calcium greens like kale, spinach, and parsley are fine in rotation but should not be the only greens. For more ideas, see best vegetables for guinea pigs.
4. Fruit and Treats (Occasional)
Fruit is high in sugar, so keep it to a small piece a few times a week. Apple (without seeds), strawberry, melon, and blueberry are popular. Skip commercial treat sticks, yogurt drops, and seed mixes. Never feed chocolate, onions, garlic, avocado, or rhubarb. The full list is in what foods are toxic to guinea pigs.
Water and Vitamin C
Provide fresh water every day in a bottle or heavy bowl. If your vet suggests a vitamin C supplement, follow their dosing guidance rather than adding drops to the water yourself, since vitamin C breaks down quickly and can change how much your pig drinks.
Common Feeding Mistakes
- Offering too many pellets and not enough hay
- Feeding rabbit food, which lacks vitamin C
- Introducing several new foods at once, which can cause diarrhea or gas
- Leaving wilted vegetables in the cage
Bottom Line
Unlimited hay, a measured portion of plain pellets, a cup of fresh veggies, and the occasional fruit treat give most adult guinea pigs everything they need. Introduce new foods one at a time and watch their stool. If your guinea pig stops eating, call an exotics vet right away.
This article is general information, not veterinary advice. Ask your vet about your guinea pig’s diet and any health concerns.
