Since working in nutrition, I have read incredible stories about vitamin C. One day, it would cure cancer; the next day, it would be used by the Chinese to treat coronavirus. Even if it is true that there have always been battles of ideas and conflicts of interest between laboratories that manufacture expensive drugs and more natural solutions, the case of vitamin C is particular since no regulatory body nor any independent research laboratory has ever been able to confirm the extraordinary effects that can sometimes be seen on the internet.
This situation is different from other natural substances. For example, in Artemisia against malaria, many laboratories try to make people believe it is ineffective, but the WHO has validated its effectiveness. We find a similar situation with turmeric: a miracle food supplement, according to sellers, capable of treating most illnesses. In reality, it is very ineffective, with thousands of faked studies (see my article on turmeric ).
Regarding vitamin C, its history is special because it was widely studied and put forward by the only man to have won two Nobel Prizes: Linus Pauling. This article, therefore, aims to disentangle fact from fiction based on independent scientific data: is vitamin C a miracle substance whose effects they want to hide from us, or is it still an internet scam?
Why The Question Of Vitamin C Requirements Unleashes Passions
About 40 million years ago, our ancestors lived near the equator with an abundance of vitamin C-rich fruits that they ate all day. Therefore, their vitamin C intake was high, and there was no longer any need for the body to waste energy synthesizing this abundant substance. The gene activating the enzyme (L-gulono-gamma-lactone oxidase), which transforms glucose into ascorbic acid (vitamin C’s chemical), has gone dormant.
Since then, we have been dependent on dietary intake of vitamin C. The non-functional gene for this enzyme still exists in humans and has been found: it is located on chromosome 8 at location p21. Very few mammals share this characteristic with us. This is the case for higher primates (macaque, African green monkey), the guinea pig and certain bats. For others who synthesize it in their liver or kidneys, it is not a vitamin.
Since this discovery, the question of humans’ real and optimal vitamin C needs has been debated. Indeed, the daily intakes recommended by health authorities ( between 90 and 110 mg per day ) are only established to prevent the severe and easily observable vitamin C deficiency called scurvy, characterized by gingival bleeding, fatigue, loosening teeth, and death.
These contributions have never been formulated to “place the body in optimal functioning conditions”. The observation of higher primates (which no longer synthesize vitamin C) in their natural environment has revealed daily vitamin C intakes between 2000 mg and 8000 mg, raising the question even more.
What Are Our Real Vitamin C Needs?
The rest of the story has a lot to do with Linus Pauling, a scientist who will mark history forever since he is the only man in the world to have been awarded two Nobel Prizes: a Nobel Prize in Chemistry in 1954 for his contribution to the discovery of the structure of proteins and a Nobel Peace Prize in 1962 for his fight of more than 10 years against nuclear tests in the atmosphere.Â
His notoriety does not come from his incredible knowledge of quantum physics or chemistry. However, it earned him called a genius by Albert Einstein, still, rather from his remarkable work on vitamins, particularly vitamin C. In 1970, he published a book that shook the medical world for more than 20 years: Vitamin C and the common cold, in which he argued that vitamin C supplementation could reduce the risk of colds and reduce the duration of symptoms.
He would later assert that this vitamin can prevent cardiovascular diseases based on the observation that animals that produce vitamin C do not experience these diseases. Several hundred scientific studies have been carried out over 50 years on vitamin C’s effects. Certain elements are particularly clear: athletes have greater needs for vitamin C than sedentary people, particularly sports athletes. Endurance.
In them, an intake of 500 to 1000 mg per day helps maintain an efficient immune system and reduce the frequency and symptoms of colds. Similar intakes should be recommended for smokers because tobacco significantly increases the need for vitamin C. At the age of 72, Linus Pauling had a young man’s health.Â
He set up the Institute for Orthomolecular Medicine in California, a research organization focused on using vitamins and micronutrients to prevent or treat disease. Today, the institute has been moved to the University of Oregon, which occupies the largest building named the Linus Pauling Institute. The institute is mainly funded by the US Department of Health, which allows it to maintain its independence and continue research on micronutrients, particularly vitamin C.Â
Today, led by Professor Balz Frei, a scholar with an arm-length curriculum vitae (professor of nutrition at Harvard University, professor of molecular toxicology, professor of biochemistry and medicine and rewarded with multiple scientific prizes), the institute considers that the optimum vitamin C requirements for (sedentary) humans are “at least 400 mg per day”. At this dose, researchers at the Linus Pauling Institute believe that very significant beneficial effects are obtained on resistance to stress, the prevention and treatment of high blood pressure, the health of blood vessels and arteries, and cancer prevention.
Effects Of Supplementation With High Doses Of Vitamin C
Mega Doses Of Vitamin C And Cancer
What about the mega doses of vitamin C (between 2 and 15 grams per day) so popular in alternative circles but also promoted by Linus Pauling at one point in his life? Several studies have been carried out on the question. All the meta-analyses carried out (analysis of a set of studies on the same subject) come to the same conclusion: mega doses of vitamin C are not more effective in preventing cold and do not seem to have any particular benefit, but have side effects: acceleration of transit and increased risk of kidney stones in predisposed people.Â
In terms of evolution, these results are quite astonishing because if our neighboring primates need 20 to 80 times higher intakes of vitamin C, why are we different? The answer comes from Texas pharmacology researchers. As early as the 1970s, they showed that when humans lost the ability to produce vitamin C, they simultaneously lost the activity of another enzyme, urate oxidase.Â
This enzyme helps eliminate uric acid by metabolizing it into 5-hydroxyisourate. However, it turns out that uric acid, although harmful in excess, is also an extremely powerful antioxidant in the human body (50% of the antioxidant activity in our plasma is due to uric acid). The increase in circulating uric acid would thus have replaced vitamin C, significantly reducing our needs and allowing us to survive in regions with a much less temperate climate (Northern Europe) with a mainly meat diet. And poor in fruits and vegetables.
Proponents of mega doses of vitamin C also argue that it would effectively treat cancer, provided it is administered by injection. A recent summary of the last 33 years of experimentation with vitamin C against cancer concluded that the studies are still very contradictory: sometimes effective, sometimes ineffective, no one knows to whom vitamin C injection should be recommended or in what way However, vitamin C injections seem very effective in reducing the side effects of chemotherapy at doses between 50 and 150 grams per day. No effect on cancer treatment can be observed with oral vitamin C, even with more than 10 grams daily.
Are Megadoses Of Vitamin C Bad For Athletes?
Finally, two studies found that people who take more than 1000 mg per day of vitamin C have a higher risk of cataracts, through a currently undetermined mechanism. In endurance athletes, a recent study showed that high doses of vitamins C (1000 mg) and E (235 mg) could reduce the ability to adapt to exercise.Â
A recent analysis of around ten studies that tested the effect of high-dose antioxidant supplementation on athletes concluded that the latter was useless or counterproductive for performance. These results are not surprising: adaptation to physical (or psychological) stress first requires that the stress is well felt by the body to adapt and strengthen itself. If large doses of antioxidants block this feeling, adaptation is impossible, and progression is slowed.
Considering all these elements, I do not recommend healthy people take more than 500 mg per day for sedentary people and 1000 mg per day for endurance or strength athletes. I do not recommend combining vitamin C with other isolated, concentrated antioxidants (high doses). In modest doses, this does not pose a problem.
Vitamin C is frequently sold in the form of “natural” dietary supplements such as “acerola vitamin C “, but numerous scientific studies have demonstrated that there is no difference between natural vitamin C and manufactured synthetic vitamin C. in the laboratory because the two molecules are strictly identical and therefore have the same effects in the body. The only real difference is the price, which is ridiculous with synthetic vitamin C and exorbitant with “natural vitamin C”. So take the cheapest vitamin C without questionable excipients (chemical sweeteners or additives).
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