Unlike humans and guinea pigs, dogs can synthesize their own vitamin C in the liver, which means it is not technically an essential dietary nutrient. However, supplemental vitamin C may benefit dogs under stress, during illness, or in old age when the body's production capacity declines. Vitamin C is a powerful antioxidant that supports immune function, collagen synthesis, and iron absorption from plant sources.
A few florets of broccoli (about 50g) provide roughly 45mg of vitamin C — while dogs do not have a strict daily requirement (they make their own), supplemental amounts of up to 100mg per day may benefit stressed, senior, or recovering dogs. Fresh fruits and vegetables like bell peppers, broccoli, strawberries, and kale naturally provide vitamin C as part of a varied diet.
0.03% of daily nutrient intake
Vitamin C makes up 0.03% of your dog's total daily nutritional requirements by weight. That's a tiny amount — but it matters.
True vitamin C deficiency (scurvy) is extremely rare in dogs because they produce their own. In rare cases of liver disease or extreme metabolic stress, dogs may show signs similar to scurvy: bleeding gums, slow wound healing, joint swelling, and lethargy. These situations require veterinary intervention.
Excess vitamin C is excreted in urine, but very high doses can cause gastrointestinal upset (diarrhea) and may contribute to calcium oxalate bladder stones in predisposed dogs. Routine supplementation is generally unnecessary for healthy dogs.
| Life Stage | Size | Min | Max | Unit | Notes |
|---|---|---|---|---|---|
| Adult | medium 10-25kg | 0 | 100 | mg | Dogs synthesize their own vitamin C. Supplementation is optional but may benefit stressed, ill, or senior dogs. |
Source: general veterinary consensus
Vitamin C significantly enhances the absorption of non-heme iron (the type found in plant foods like spinach and lentils) by converting it to a more absorbable form in the gut.
What this means: If you feed plant-based iron sources, pairing them with vitamin C-rich foods (bell peppers, broccoli) improves iron absorption. This is less important for heme iron from meat, which is already well absorbed.
Vitamin C regenerates vitamin E after it has neutralized a free radical, effectively recycling it for reuse. Together they provide more antioxidant protection than either alone.
What this means: Feeding foods rich in both vitamins (like broccoli and kale) provides synergistic antioxidant benefits. If supplementing vitamin E (for example, alongside fish oil), ensuring adequate vitamin C intake maximizes the antioxidant effect.
