Do Humans Need Vitamin C?

Do Humans Need Vitamin C?

Do Humans Need Vitamin C?

Do humans need Vitamin C?” I wondered…

When I first decided to experiment with the Carnivore Diet, I had some concerns.

I was going from Keto to Carnivore and worried about the lack of fiber and the elimination of many “healthy” plant-based antioxidants. I was curious about its associations with cancer and correlations with disease. I wondered about what a carnivore’s carbon footprint must look like.

But what concerned me the most was vitamin C.

Vitamin C

Vitamin C is a powerful antioxidant and Linus Pauling, one of my favorite scientists in history, believed it was the solution to all diseases of civilization. Together with vitamin E it reduces lipid peroxidation. It’s a cofactor in many enzymatic reactions – including those in the making of collagen and carnitine.

But what I was most concerned about was that inadequate vitamin C can result in scurvy.


Vitamin C is essential in the synthesis of collagen. Many animals can synthesize vitamin C out of glucose. But humans as well as primates like monkeys and apes lost this ability about 60 million years ago. We lack the enzyme (L-gulonolactone oxidase – GULO) that is required in the last step in the synthesis of Vitamin C from glucose. [r]

Because of this, we must consume our vitamin C or risk the consequences of scurvy – fatigue, weakness, gum disease, poor wound healing, and potentially death from infection or bleeding.


Looking through the lens of evolution has influenced my nutrition views as much as looking through the lens of microscopes. Evolution doesn’t tend to just drop things because they are no longer useful. It selects for advantages.

But what’s the advantage of not synthesizing an essential vitamin?

Uric Acid

In our evolutionary history, we also loss the ability to break down uric acid. And there is a striking parallel between the loss of the ability to synthesize vitamin C and the loss of the ability to break down uric acid.

Uric acid is a major antioxidant, more potent than Vitamin C.

Losing the ability to break down uric acid resulted in higher levels of uric acid in primates. These high levels are thought to explain the relatively long lifespans of apes.

It’s entirely possible, if not likely, that increased uric acid took over many of the antioxidant functions of vitamin C.

Glucose-Ascorbate Antagonism Theory (GAA Theory)

When we look at animals that make their own vitamin C, we find they make less of it when carbohydrates are low.

Which is interesting – low carbohydrates would indicate a lower vitamin C intake from the diet and presumably a higher need to make it endogenously.

Yet we see the opposite.

The more carbohydrates/glucose an animal eats, the more vitamin C it gets from its food, AND the more it makes endogenously.

This suggests that more vitamin C is needed in a glucose-based metabolism.

It also suggests that Vitamin C requirements may be less in low-carbohydrate conditions. [r]

This makes sense though.

Glucose and vitamin C look very similar. There molecules are nearly identical. They even use the same pathways for absorption into cells. Because of this they directly compete with each other for uptake into cells. And glucose wins out preferentially.

Orange Juice

orange juice and vitamin cThis is why drinking orange juice doesn’t make sense (at least for vitamin C purposes). It may have a lot of vitamin C, but it’s high sugar content blocks that vitamin C from getting used.

This is also why diabetics with high blood sugar have strikingly similar symptoms that are seen with scurvy. They are vitamin C deficient even though they may be getting “adequate” intake from their diet or supplements. The glucose blocks out the vitamin C.

In fact, the benefit of vitamin C in disease may not have anything to do with its antioxidant properties. Rather, high dose vitamin C could sometimes compensate for the glucose overload and insulin resistance that is characteristic of many of the diseases of modern man.

Linus Pauling was on to something after-all.

Meat, Vitamin C, and Scurvy

Our food labeling would lead us to believe that meat doesn’t contain vitamin C. But it does. Sailors prevented and cured scurvy with fresh meat. (r)

And in the absence of carbohydrates far less vitamin c is needed. It doesn’t have to constantly compete with glucose for uptake.

The amount of vitamin C to prevent scurvy is just 10 mg/day in the context of a high carb diet.

In a low/no carb diet, even less is needed.

On the Carnivore Diet, the meat content plus the absence of carbs creates an environment that doesn’t result in scurvy.

Vitamin C’s role as a cofactor in hydroxylation reactions (transferring a hydroxl group to the amino acids lysine and proline), is what helps make the building blocks of collagen. But meat comes “pre-packaged” with hydroxylysine and hydroxyproline – further bypassing much of the requirement for vitamin C.

So even though the amount of dietary vitamin C consumed on a meat-based diet may be lower compared to that of a plant-based diets with fruits and vegetables, the former has a lower need for vitamin C with higher bioavailability.

Antioxidant Properties

Well if we don’t need Vitamin C to prevent scurvy on a meat-based diet, surely we need its antioxidant properties, right?

Well, no.

Endogenously synthesized uric acid and glutathione (natural human antioxidants) are much more powerful and take over much of the roles that vitamin C would play. Plus, in a low carb diet these powerhouses are up-regulated.

In essence, we “turn on” more of our most powerful antioxidants. In addition glutathione and uric acid spare vitamin C by recycling it.

So Do Humans Need Vitamin C?

Yep we do.

But how much is entirely dependent on the context of one’s diet. If you eat a high carb diet, you need a lot more vitamin C to compete with those carbs for uptake.

Contrary to popular belief, meat does contain vitamin C, and in the context of a low/no carb diet like the Carnivore Diet, very little vitamin C is actually needed to prevent scurvy. This environment also up-regulates our naturally produced antioxidants. It’s likely the loss of endogenously synthesized vitamin C was not detrimental to our hominid ancestors but rather conferred a competitive advantage (perhaps from the uptick of the likes of uric acid and glutathione) that coincides with our remarkable ability to recycle the vitamin c.

However, a mismatch, the “discordance theory,” between our current diet and ancestral physiology is likely the cause of vitamin C deficiencies and their association with disease.

As is seen time-and-again in research, the clinical manifestation (vitamin C deficiency for example) is the consequence, not the cause, that can only be understood in the proper context.

If you’d like to learn more about micronutrients and avoiding deficiencies, and how to make a meat-based / carnivore diet work, I’d highly recommend watching the Meat Health Masterclass:

55 Replies to “Do Humans Need Vitamin C?”

  1. Explain the Inuit or other populations (I worked with Inupiaqs in the Alaskan Arctic for 30 years) who had no access to “high Vitamin C” for thousands of years? They lived much the same as my European and Neanderthal ancestors did during the Ice Ages. Eating only meat and no opportunity for plant matter at all but for maybe 4 months a year. How am I (and others) here now if long term health is so impacted? Read Vilhjalmur Stefansson and others to get an idea of their pre-Western diet health. Better than yours or mine, I’ll wager.

  2. enjoyed the article i am a traditionally trained md internal medicine i am a big proponent of vitaminc actually believe as i think the author does, that many millions of people are likely suffering from chronic scurvy, a form that does not kill them quickly, but rather slowly deteriorates their bodies the high carb diet we have developed over the past few thousand years is blocking the little vit c most people consume daily danish scientist stephanson demonstrated years ago what the author here says fresh meat without carbs will prevent the immediate phase of fatal scurvy, just leave out the carbs limes will not be needed but longterm optimal health requires high amounts vit c

    1. There is Vitamin C in the muscle and the liver (all depends on what kind of meat, what cut, etc…) – cooking can cause some loss of vitamin c, again it depends on the method, length etc.

    2. Chicken livers are a good source of vitamin C. Ruminant livers and brains have a smaller amount and muscle meats a tiny amount. However, the lungs and sweetbreads of cattle, goats and sheep are even better sources than chicken liver. Lungs and sweetbreads are the best sources on a carnivore diet and provide far more than the small amount needed on this diet.

  3. This is great stuff but you are missing one important point – vitamin C is required to hydroxylate l-carnitine, the fatty acid transporter. This is why depression and fatigue are symptoms of scurvy. Meat is a great source of l-carnitine and meat intake on a carnivore diet is very high, so the requirement for vitamin C to synthesise carnitine is reduced and possibly eliminated altogether.
    Vitamin C is also required for some other reactions – from memory one of these is a stage of vitamin D activation – that can be side-stepped if the products are supplied from animal sources.

    Has any carnivore dieter had their ascorbate levels tested?

  4. Hi there, fascinating stuff. Are you able to provide sources for many of the points? It makes sense to me but I like having further reading to further understand and also be sure that this is verified stuff 🙂

    1. Without any fresh meat and just dried meat and ghee – I’d probably play it safe and take a vitamin c supplement. (but I also wouldn’t recommend just dry meat – I’d try and eat as much fresh meat as I could).

      1. What’s your definition of fresh meat? As in it needs to be eaten raw? Rare steak I’d imagine would be ok. But there’s a lot of people who seem fine with just burgers, I’m not sure how many fully cook them vs eat them medium rare. Thanks.

        1. That’s a really good question – and no by “fresh” I’m not referring to raw meat – but rather meat that hasn’t been dried like jerky or overly processed like hot dogs.

    1. They were eating a combination of dried meat and high carbohydrate foods (biscuits) that contained virtually no vitamin c. The carbs increase the need for vitamin c and the dried meat has little to no vitamin c. It’s that combination that caused scurvy. Fresh meat has vitamin c (especially if eating organs) and a low/no carb diet dramatically decreases the amount of vitamin c needed. Hope that makes sense!

  5. Vitamin C is needed in myriad ways for healing therefore it would seem less healing is needed if we omit plants. Glad I take my ascorbic acid in water. Also handy that bowel tolerance indicates how much we need. I’ll be interested to see whether my tolerance goes down on my 30 day carnivore experiment!

  6. so impressed by this article… all this time I was supplementing with vit C by adding its powder form to orange juice.. still it helped in cases like start of flu or running nose and stopped the development of disease, but I wonder how much stronger it would become if dissolved in water instead of juice… also now I see how stupid idea is eating ANY carbs in lower immune system times.. thanks for sharing such eye opening knowledge!

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