What Do Guinea Pigs Eat

Introduction

Understanding what guinea pigs eat is essential for keeping them healthy. Guinea pigs are strict herbivores with a unique nutritional requirement — they cannot produce their own vitamin C and must get it from their diet every single day. Here's a complete breakdown of what guinea pigs eat.

Hay — The Foundation (80% of Diet)

Hay is the most important food for guinea pigs and must be available 24/7. It provides the long-strand fiber that keeps the digestive system moving and wears down continuously growing teeth. Oxbow Orchard Grass Hay is an excellent everyday choice. Kaytee Timothy Hay Blend Cubes can be offered as an enriching supplement. Use a hay feeder rack to keep hay fresh and off the cage floor.

Fresh Vegetables — Daily Vitamin C Source

Fresh vegetables are essential and should be offered daily — approximately 1–2 cups per guinea pig per day. The best choices include:

• Bell pepper (red, yellow, or orange) — the single best source of vitamin C for guinea pigs; offer a small piece daily
• Romaine lettuce — hydrating, nutritious, and well-tolerated; excellent daily staple
• Cilantro — most guinea pigs love it; good vitamin C content
• Parsley — high in vitamin C and K; offer 2–3 times per week (high calcium)
• Kale — nutritious but high in calcium; limit to 2–3 times per week
• Cucumber — hydrating; great in summer
• Zucchini — mild and easy to digest
• Bok choy — gentle on the digestive system
• Spinach — safe occasionally; high in oxalates so don't feed daily

Pellets — Concentrated Nutrition

High-quality pellets provide vitamins and minerals that may be lacking in hay and vegetables alone. Choose a timothy-based pellet with added vitamin C. Wild Harvest Advanced Nutrition Guinea Pig Food and Vitakraft Menu Guinea Pig Pellets are both solid options. Feed approximately ⅛ cup per guinea pig per day. Avoid muesli-style mixes.

Vitamin C Supplementation

Even with a good diet, many guinea pigs benefit from additional vitamin C. Oxbow Natural Science Vitamin C Supplement is a vet-recommended option made with timothy hay. Do not add vitamin C to water — it degrades quickly and may make water taste unpleasant.

Fruits — Occasional Treats Only

Fruits are high in sugar and should be given very sparingly — a small piece once or twice a week maximum. Safe options include apple (no seeds), strawberry, blueberry, and watermelon. Oxbow Simple Rewards Apple Banana Treats are a healthy commercial treat option.

Water

Fresh water must always be available via a no-drip water bottle. Change daily and clean the bottle weekly.

Foods Guinea Pigs Cannot Eat

• Onions, garlic, leeks — toxic
• Avocado — toxic
• Rhubarb — toxic
• Chocolate — toxic
• Iceberg lettuce — causes diarrhea
• Potatoes — too starchy
• Dairy and meat — guinea pigs are herbivores

Conclusion

Guinea pigs eat a herbivorous diet centered on unlimited hay, daily fresh vegetables rich in vitamin C, measured pellets, and clean water. Bell pepper is the single most important vegetable to include daily. Get the vitamin C right and your guinea pig will thrive.