Vitamin C

Vitamin C, or ascorbic acid, is a water-soluble antioxidant involved in collagen synthesis and immune function. The crucial point that surprises many owners is that, unlike humans, dogs and cats make their own vitamin C in the liver from glucose, so it is not classed as an essential dietary nutrient for healthy animals, and FEDIAF sets no minimum requirement for it (FEDIAF, 2021). This is a genuine difference from human nutrition and a frequent source of misunderstanding, since people often assume their pet needs a vitamin C supply just as they do. Vitamin C is nonetheless added to some premium foods, mainly as an antioxidant to protect fats and other sensitive nutrients, often working in synergy with [vitamin E](/glossary/vitamin-e), rather than to meet a dietary need. Situations such as intense stress, prolonged exertion or illness may raise requirements somewhat, but evidence that routine supplementation benefits healthy animals is limited. Over-supplementation is not entirely harmless either: prolonged high doses may promote certain oxalate urinary stones, so more is not better. Any supplementation should be discussed with a veterinarian and is not meant to correct a deficiency, which does not arise spontaneously in a healthy individual. Vitamin C also assists the body's own synthesis of [L-carnitine](/glossary/l-carnitine). See the [Petipedia glossary](/glossary).

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General documentary information. For an individual animal, a veterinarian's advice takes precedence over any online content.