Vitamin C (ascorbic acid) is a water-soluble vitamin used in pet foods as an antioxidant, collagen-synthesis cofactor and immune-supportive nutrient. Dogs and cats, unlike humans, can synthesize vitamin C in the liver (L-gulonolactone oxidase enzyme is active). Therefore, vitamin C is not essential for dogs and cats. However, during periods of stress, disease, aging and intense exercise, endogenous production may be insufficient and additional support may be beneficial.
| Chemical Name | L-Ascorbic Acid |
| Resource Type | Vitamin (Water Soluble) |
| Function | Antioxidant / Collagen Synthesis / Immune Support |
| Dog Need | AAFCO no minimum (endogenous synthesis) |
| Cat Needs | AAFCO no minimum (endogenous synthesis) |
| Endogenous Synthesis | Produced in the liver (gulonolactone oxidase) |
| Safe Upper Limit | Large (water soluble, excess is excreted) |
| Discussion Level | low |
Vitamin C, It is a safe and beneficial antioxidant supplement.. Although not essential, it provides additional support during times of stress. Its contribution to collagen synthesis is valuable for joint and connective tissue health. It is not toxic even in overdose.
Why Added?
- Antioxidant: Neutralizes free radicals, regenerates vitamin E
- Collagen synthesis: Cofactor of prolyl and lysyl hydroxylase enzymes—joint, tendon and skin health
- Immune support: Increases neutrophil function and lymphocyte proliferation
- Iron absorption: Increases the absorption of non-heme iron
Oxalate Stone and Urine pH
High dose vitamin C supplementation, as a result of its metabolism to oxalate production and may increase the risk of calcium oxalate urinary stones. It may also help dissolve struvite stones by lowering (acidifying) urine pH, but may facilitate oxalate stone formation. It should be used under the supervision of a veterinarian in animals with a history of urinary stones.
Frequently Asked Questions
If dogs produce vitamin C, why is it added to food?
Endogenous production is usually sufficient in healthy animals. However, the need may increase during periods of stress, illness, surgery and aging. Additionally, vitamin C works synergistically with other antioxidants (vitamin E) in the food. Since it is water soluble, excess is excreted in the urine and the risk of toxic accumulation is very low.
Related VetKriter Tools
Bibliography
- NRC (National Research Council). (2006). Nutrient Requirements of Dogs and Cats. National Academies Press.
- FEDIAF (European Pet Food Industry Federation). (2024). Nutritional Guidelines.