Unlike guinea pigs and humans, cats can synthesize their own vitamin C (ascorbic acid) in the liver, which means it is not considered an essential dietary nutrient for healthy cats. However, vitamin C still plays important roles as an antioxidant, supporting collagen formation for healthy skin, tendons, and blood vessels, enhancing immune cell function, and improving iron absorption. During periods of stress, illness, or recovery from surgery, your cat's endogenous vitamin C production may not keep pace with demand, and some veterinarians recommend supplementation in these situations. Vitamin C also works synergistically with vitamin E to provide comprehensive antioxidant protection.
Your cat produces roughly 40–60mg of vitamin C per day in their liver, which is typically sufficient. Dietary supplementation is unnecessary for healthy cats. If your veterinarian recommends supplementation during illness or stress, doses of 50–100mg per day are commonly used. A small piece of bell pepper (about 20g) contains roughly 25mg of vitamin C, though cats are unlikely to eat vegetables voluntarily.
0.18% of daily nutrient intake
Vitamin C makes up 0.18% of your cat's total daily nutritional requirements by weight. That's a tiny amount — but it matters.
Clinical vitamin C deficiency is extremely rare in healthy cats because they synthesize their own. Cats with severe liver disease may have impaired synthesis, potentially contributing to poor wound healing or immune suppression, but this is a secondary concern to the underlying liver condition.
Excess vitamin C is excreted in urine, but very high doses can increase urinary oxalate levels, which may promote calcium oxalate urinary stones — a significant concern for cats, since calcium oxalate uroliths are already common. Do not supplement vitamin C at high doses without veterinary guidance.
| Life Stage | Size | Min | Max | Unit | Notes |
|---|---|---|---|---|---|
| Adult | — | 0 | 100 | mg | Cats synthesize their own vitamin C and have no dietary requirement. Supplementation may be considered during illness or stress under veterinary guidance. |
Source: NRC 2006, general veterinary consensus
