How do carnivores get their vitamin C?

December 9, 2025 •

3 min read

Unlike humans and certain other animals, the vast majority of mammals possess a gene that allows them to produce their own vitamin C internally. This biological ability is the primary reason why true carnivores do not need to consume fruits and vegetables to get their vitamin C, successfully avoiding deficiency diseases like scurvy.

Quick Summary

Carnivores get vitamin C by synthesizing it in their liver and by consuming nutrient-dense organ meats from their prey. This innate ability, combined with a metabolic process that reduces their overall vitamin C needs, explains why they thrive on a meat-only diet.

Key Points

Internal Production: Most mammals, including carnivores, produce their own vitamin C internally via a functional GULO enzyme in the liver.
Organ Meats: Wild carnivores get a dietary boost of vitamin C by consuming nutrient-rich organs like the liver, kidney, and spleen of their fresh prey.
Reduced Need: A low-carb diet reduces competition between glucose and vitamin C for cellular absorption pathways, meaning carnivores require less of the nutrient overall.
Scurvy Immunity: The ability to synthesize their own vitamin C is why true carnivores are immune to scurvy, a deficiency disease that affects humans.
Raw vs. Cooked: The small amount of vitamin C present in muscle meat is largely destroyed by cooking, which is why eating fresh, raw meat is crucial for carnivores relying on dietary intake.
Human vs. Carnivore: Humans, primates, and guinea pigs lack the gene for vitamin C synthesis, making them dependent on external sources, unlike most carnivores.

Internal Synthesis: The Body's Factory

At the core of the carnivore's strategy for getting vitamin C is the process of endogenous synthesis, meaning they can produce it within their own bodies. This is possible due to a functional liver enzyme called L-gulonolactone oxidase (GULO), which enables the conversion of glucose into ascorbic acid, the active form of vitamin C. Most mammals, including felines and canines, possess a working GULO gene, making them self-sufficient for this vital nutrient.

Humans and certain other species, such as primates and guinea pigs, lack a functional GULO gene, a result of an ancient genetic mutation. This evolutionary difference forces us to rely entirely on dietary sources for vitamin C, designating it as a 'vitamin' for us. For a lion, a tiger, or a wild dog, however, ascorbic acid is simply another chemical their body manufactures on demand.

Dietary Sources: Nature's Bioavailability

For carnivores that consume fresh, raw prey, dietary intake also plays a role in their vitamin C levels. While muscle meat contains only trace amounts, the consumption of other parts of the animal, particularly organ meats, provides a bioavailable source of vitamin C. This is a key reason why wild carnivores often instinctively eat the nutrient-rich organs of their kill first. Cooking meat, as humans do, can destroy much of its natural vitamin C content, but this is not a concern for animals consuming their prey raw.

Key dietary sources for carnivores include:

Organ Meats: Liver, kidneys, and spleen contain higher concentrations of vitamin C than muscle meat.
Blood: Fresh blood also contributes to a carnivore's overall intake of nutrients.
Stomach Contents: Some carnivores, particularly wild canids and felines, will consume the partially digested stomach contents of their herbivorous prey, indirectly ingesting some plant-derived nutrients.
Fish Roe: A valuable source of vitamin C and other nutrients for carnivorous marine animals and those that consume fish.

The Carb-Free Connection

Another factor in a carnivore's vitamin C balance is the absence of carbohydrates in their diet. Vitamin C and glucose compete for the same absorption pathways in the body. When a diet is low in carbohydrates, there is less competition for these pathways, meaning the body can absorb and utilize the vitamin C it has much more efficiently. This means that even a smaller amount of vitamin C is sufficient for an animal on a zero-carb diet compared to one with a high-carb intake.

Synthesis vs. Dietary Intake in Carnivores


Feature	Internal Synthesis	Dietary Intake (Organ Meats)
Mechanism	The body's liver produces vitamin C from glucose via the GULO enzyme.	Consumption of fresh organ meats, blood, and other animal products.
Necessity	Primary method for carnivores to meet vitamin C needs.	Supplements the body's internal production.
Carb Interaction	Low-carb diet reduces the need for large amounts, making endogenous production sufficient.	Vitamin C from food is absorbed more efficiently due to less competition from glucose.
Cooking Effects	Not affected by cooking.	Nutrient content is destroyed by heat, highlighting the importance of raw consumption.
Reliability	Consistent and reliable for species with a functional GULO gene.	Dependent on the availability of fresh, raw prey and consumption of nutrient-rich parts.

What About Modern Carnivore Diets?

For humans following a carnivore-style diet, the situation is different. Without a working GULO gene, they must obtain vitamin C from their food. While the amount needed on a low-carb diet is significantly lower than for a standard diet, it is not zero. Followers of this diet rely on fresh, raw, or lightly cooked muscle meat and, most importantly, organ meats like liver and spleen, which contain higher amounts of vitamin C. Historically, indigenous populations like the Inuit have survived on meat-heavy diets by consuming all parts of the animal, including the raw organs, blood, and skin. However, modern, processed meats offer very little vitamin C. This is why supplementation is often recommended for humans on strict carnivore diets if organ meats are not regularly consumed.

Conclusion

While the concept of a meat-only diet providing all necessary nutrients seems counterintuitive from a human perspective, the biological reality for most carnivores is quite different. The ability to synthesize their own vitamin C, combined with the dietary intake of fresh organ meats, ensures they remain healthy and free from deficiencies. Understanding this biological distinction reveals how carnivores have successfully thrived on their diets for millennia, a nutritional strategy fundamentally different from our own. To explore the broader mechanisms of how animals obtain essential nutrients, see this detailed resource on vitamin C loss in vertebrates.

Frequently Asked Questions

No, domestic cats and dogs can produce their own vitamin C in their livers and therefore do not get scurvy under normal circumstances.

Humans, primates, and a few other species possess a genetic mutation that disabled the enzyme necessary for vitamin C synthesis, while most other animals, including carnivores, retain this ability.

The highest concentrations of vitamin C are found in organ meats such as the liver, kidney, and spleen of fresh prey, though small amounts are also present in muscle meat and blood.

Yes, cooking meat destroys much of its natural vitamin C content. This is why wild carnivores that eat fresh, raw prey benefit more from dietary vitamin C than humans consuming cooked meat.

Most true carnivores do not eat plants. Some species might ingest small amounts of plant matter incidentally or by consuming the stomach contents of herbivorous prey, but this is not their primary source of vitamins.

For those on a human carnivore diet, vitamin C and glucose compete for the same absorption pathways. With no carbohydrates present, the body’s need for vitamin C is lower, and it can be absorbed more efficiently.

Like other mammals (except for a few lineages including primates), polar bears can produce their own vitamin C internally, eliminating any need for a dietary source and preventing scurvy.