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Introduction – Vitamin C on Low Carb Diet

Do you need Vitamin C on low carb diets like the Paleo, carnivore or ketogenic diets? And if you do need to supplement Vitamin C on low carb diets, what’s the best way to get enough of this essential vitamin to prevent any health problems?

What is Vitamin C?

Vitamin C is a water-soluble vitamin, also called l-ascorbic acid. It’s classified as a vitamin because its a chemical that the body can’t produce on its own. Instead, vitamin C (like all vitamins) has to come from an external source such as food.

The main reason for the vitamin C requirement in humans is due to the inability of the human body to make vitamin C (ascorbic acid) from glucose due to missing the enzyme L-gulonolactone oxidase.

Scurvy and Vitamin C Deficiency

Scurvy is probably the most well-known type of vitamin C deficiency. Scurvy was a common problem in sailors and other world travellers and expeditions that had limited access to foods high in Vitamin C foods. The connection between scurvy and Vitamin C deficiency was discovered by British naval physician James Lind, who did one of the first clinical trials on British Navy sailors and found that adding citrus fruits like limes and lemons decreased the outbreak of scurvy on ships.

It is important to note that the sailors typically ate a very limited diet of dried meats and high carb foods like biscuits, so it shouldn’t be a surprise they suffered from nutritional deficiencies.

Artic explorers found that the Inuits got enough Vitamin C on a low carb diet and did not suffer from scurvy. Their diet consisted mainly of hunted animals like seals and fish, with a focus on eating the fat and organ meats.

The role of Vitamin C in the human body

Vitamin C places an important role in the body and is used to produce collagen, protein synthesis as well as acting as an antioxidant. Vitamin C also helps the gut absorb iron and is an important part of helping the immune system work properly.

How much Vitamin C does the body need?

When we talk about how much of a supplement such as a vitamin or mineral is needed in the diet, we can use several different terms. It’s important to understand the difference in the terminology and what each term correlates to in regards to the amount needed by an individual. 

Since there is a wide variation between the amount of vitamins and minerals needed by different individuals, the guidelines will list different amounts if we are talking about the minimal amount needed to prevent disease or the average dose needed for a certain percentage of the population.

The Recommended Daily Allowance (RDA) level in the U.S. is the amount of the supplement that will meet the daily requirements of 97.5% of the population. The Estimated Average Requirement ( EAR) is the amount that will meet the daily requirements of 50% of the population.

Vitamin C requirements on low carb and keto diets

Being on a low carb or ketogenic diet may significantly reduce your daily requirements for vitamin C. Glucose and vitamin C compete for the same receptor transport on cell walls. the presence of glucose prevents vitamin C from entering the cells.

Vitamin C and blood glucose levels

Recent studies in diabetics have shown that supplementation of Vitamin C can help lower fasting and after-meals (post-prandial) blood sugars. A small 12-week study of Type 2 diabetics on the drug metformin (Glucophage) found that supplementing with 500 mg of vitamin C twice a day lowered their blood glucose levels compared to similar diabetic patients on metformin that did not supplement with vitamin C. The study also found a small (but not statistically significant) drop in the HgA1c or glycosylated hemoglobin of the vitamin C supplement group. 

Is it possible to get too little Vitamin C on low carb diet?

There are two case reports of children developing scurvy on the ketogenic diet. One case study was in a 5-year old autistic child while on the ketogenic diet while a second case study was reported in a 9-year old girl who was on the ketogenic diet for refractory seizures. Both children, even though they were on the ketogenic diet, had a much more restrictive diet where neither ate any fruits or vegetables for several months while on the diet. Both children had their scurvy resolve when started on Vitamin C supplementation.

While the ketogenic diet does require a much lower carbohydrate item, it doesn’t completely restrict vegetables or even fruit, so its still possible to get the RDA amount of Vitamin C while on the ketogenic or low carb diet.

Best Foods High in Vitamin C for Low Carb Diet

Most people think of oranges and other citrus fruits as being the foods highest in Vitamin C. Some people on low carb diets might worry that foods high in Vitamin C also contain too many carbohydrates. The good news is that there is a wide variety of fruits, vegetables and even animal sources to meet your daily requirements of Vitamin C on a low carb diet.

How do I get Vitamin C on a low carb diet?

Typically, most dietary recommendations for Vitamin C are from eating fruits and vegetables. So the question that comes up is how to get adequate Vitamin C on a low-carbohydrate diet like the ketogenic diet or the carnivore diet.

Organ meats tend to have to highest sources of Vitamin C (and plenty of other vitamins and minerals) and should be a part of any low-carb/keto or carnivore diet.

Organ meats with Vitamin C

Conclusion – Do you need more Vitamin C on a low carb diet?

The good news is that a very small amount of daily Vitamin C is needed on low carb diets such as the ketogenic or carnivore diet. The Recommended Daily Allowance (RDA) of Vitamin C is only 10 mg per day.

On a low-carb diet, the daily requirement is thought to be less than the typical RDA level on 10 mg/day because of the body sparing or recycling Vitamin C.

So if you eat a well-balanced diet, you won’t need to supplement Vitamin C on a low carb diet.

Learn more about the ketogenic diet with our Ketogenic Diet guide.