What Do Guinea Pigs Eat? UK Diet Guide
Guinea pigs need a diet built around unlimited hay, a measured portion of quality pellets, and a daily cup of fresh vegetables. Getting the proportions right: too many pellets or sugary fruits causes obesity and digestive problems, while too little hay leads to overgrown teeth. Here's exactly what to feed, how much, and what to avoid.
Hay Is 80% of the Diet
Timothy hay and meadow hay should be available at all times, unlimited. Guinea pigs eat roughly their own body weight in hay every day, and it serves three critical functions: wearing down their continuously growing teeth, keeping their digestive system moving, and providing the fibre their gut bacteria need.
Without enough hay, guinea pig teeth overgrow, causing pain, drooling, and inability to eat. This is one of the most common and preventable health problems in UK guinea pigs. A hay rack or hay feeder keeps it clean and accessible. Back-2-Nature Small Animal Bedding is made from the same fibre source as good hay and works well as a substrate that doesn't conflict with the hay-based diet.
Avoid Alfalfa hay for adult guinea pigs. It's too high in calcium and protein for daily use and can cause bladder stones. Alfalfa is appropriate only for pregnant or nursing guinea pigs and young pups under 6 months.
Pellets: A Measured Handful, Not a Bowl
Quality guinea pig pellets provide vitamin C and minerals that hay alone can't deliver. But pellets are calorie-dense, and overfeeding is the most common dietary mistake. One heaped tablespoon per guinea pig per day is enough.
Small Pet Select Guinea Pig Pellets are a solid option: uniform in composition (so guinea pigs can't pick and choose), fortified with vitamin C, and free from seeds, nuts, and coloured pieces that add no nutritional value. Burgess Excel Guinea Pig Food & Hay Bundle combines pellets with a hay sample, which is useful for new owners still building their feeding routine.
Check the ingredients list. The first ingredient should be a fibre source like grass meal, not cereal or corn. Avoid mixes with bright coloured pieces, as these are usually just sugar and flavouring that guinea pigs pick out first.
Fresh Vegetables: A Cup Per Day
Every guinea pig needs roughly one cup of mixed fresh vegetables daily. This provides vitamin C, hydration, and variety. Bell pepper is the single best vegetable for guinea pigs: it's high in vitamin C, low in sugar, and most guinea pigs love it. A quarter of a red or yellow bell pepper daily is ideal.
Other safe options include cucumber, carrot (in small amounts due to sugar content), broccoli (a couple of florets, not daily), romaine lettuce, and leafy greens like kale and parsley. Rotate the selection through the week to cover different nutrients.
Foods to avoid: potatoes, tomato leaves and stems (the fruit is okay in tiny amounts), onions, garlic, beans, peas, cabbage in large quantities, and anything treated with pesticides. Iceberg lettuce offers no nutritional benefit and can cause loose droppings. Never feed anything from the garden unless you're certain it's pesticide-free.
Vitamin C: The Nutrient Guinea Pigs Can't Make
Unlike most animals, guinea pigs cannot synthesise their own vitamin C. They need 10-30mg per day from their diet. Deficiency causes scurvy, which shows up as swollen joints, lethargy, rough coat, and reluctance to move.
Most quality guinea pig pellets are fortified with vitamin C, and fresh vegetables (especially bell pepper and leafy greens) provide the rest. Supplement drops are rarely necessary unless your vet advises them, typically for guinea pigs with dental problems that prevent normal eating.
Vitamin C degrades quickly in pellets, so check expiry dates and buy bags you'll use within 6-8 weeks of opening. Stored in a cool, dry place, pellets maintain their vitamin C content longer.
Fruit: A Treat, Not a Staple
Fruit is high in sugar and should be limited to a small piece once or twice a week. Apple (no seeds), strawberry, blueberry, and pear are all safe in tiny portions. Grapes are okay occasionally but very sugary. Dried fruit is too concentrated and should be avoided entirely.
Many guinea pig owners overdo the fruit because their pets react so enthusiastically to it. But guinea pigs will always prefer fruit over hay and pellets, so letting them choose would mean an unbalanced diet. Treats are for bonding, not nutrition.
Products Mentioned in This Guide
- Small Pet Select Guinea Pig Pellets - uniform vitamin C-fortified pellets without seeds or coloured pieces
- Burgess Excel Guinea Pig Food & Hay Bundle - pellets combined with hay, useful for new owners
- Back-2-Nature Small Animal Bedding 30L - fibre-based bedding that pairs well with hay-based diets
Frequently Asked Questions
Nina writes about small pets and birds for WhoPets, with a focus on proper care standards. She has owned hamsters, guinea pigs and budgerigars, and cares about evidence-based husbandry over trendy pet products.
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Last reviewed: August 28, 2026 · Evidence-based content · Contains affiliate links