Immunity: the benefits of vitamin C against infections

Friday 06th December 2024 10:07 AM

What is vitamin C used for?

Vitamin C deficiency

The history of vitamin C is associated with that of a disease, scurvy, which once affected sailors who went to sea for months and did not consume any fresh produce during their journey. Symptoms of scurvy include fatigue, bleeding gums and loose teeth. At 18^e century, it was realized that the consumption of lemon made it possible to prevent this disease, caused by a severe deficiency of vitamin C.

Identification of the ascorbic acid molecule

In 1928 Albert Szent-Gyorgyi succeeded in isolating from plant juice and adrenal gland extracts a compound which he and two other researchers would later demonstrate to be the antiscorbutic vitamin C. The first synthesis of ascorbic acid was carried out in 1933. In 1970, Linus Pauling released his best-selling work Vitamin C and the common cold.

The role of vitamin C

Vitamin C is a powerful antioxidant that acts as a cofactor in enzymatic reactions. In the body, it is involved in the formation of collagen, the production of red blood cells, immunity and wound healing. Ascorbic acid strengthens skin, tissues and bones by stimulating collagen synthesis. It supports brain activity by helping it produce several chemical messengers including norepinephrine. Vitamin C is also known to promote the absorption of non-heme iron.

Antioxidant and anti-inflammatory, vitamin C helps fight against many infections. In Let’s stop sabotaging our immunityThierry Souccar explains: “Vitamin C acts at all stages of the immune response. It stimulates the production of antibodies, also increases the speed with which T lymphocytes and B lymphocytes divide.”

Vitamin C acts at all stages of the immune response

What are the benefits of vitamin C against respiratory infections?

Vitamin C is an essential vitamin to fight winter infections and help you recover more quickly.

Vitamin C and colds

Overall, vitamin C supplementation does not really reduce the risk of colds. This is shown by an analysis by the Cochrane group comprising 29 studies (11,306 participants) on the effect of vitamin C supplementation in the prevention of colds (1). On the other hand, taking vitamin C reduces the duration and severity of colds : on average this supplementation reduces the duration of symptoms by 8% in adults and by 14% in children. In children, supplementation of 1 to 2 g per day limits the duration of symptoms by 18%.

However, a preventive role of vitamin C on colds has been highlighted. among athletes.

Vitamin C and zinc against colds

Vitamin C can be combined with zinc, especially since this mineral has demonstrated its effectiveness in preventing colds and reducing the duration of symptoms. In 2013, a review Cochrane including 16 studies (1387 participants) demonstrate the effectiveness of zinc against the common cold (2). Zinc was taken from the first day of symptoms.

Vitamin C against flu and COVID-19

Vitamin C, due to its beneficial effect on the immune system, could help fight the flu, but evidence is somewhat lacking regarding the influenza virus.

On the contrarydifferent studies have shown the benefits of vitamin C against coronavirus and its serious forms. In this specific case, vitamin C could calm the “cytokine storm” thanks to its anti-inflammatory effect, as Thierry Souccar explains in his book: “In cases of cytokine storm or sepsis, neutrophils (white blood cells) accumulate in the lungs, destroying the alveolar capillaries. Vitamin C can effectively prevent this process and limit lung damage. he said. Vitamin C would also have a favorable effect as an antioxidant molecule because “Cytokine storms are accompanied by high levels of oxidative stress. »

Vitamin C, an ally against severe forms of COVID-19

Recently, a meta-analysis evaluated the clinical effects of vitamin C supplements on COVID-19 (3). The researchers selected 22 studies, involving a total of 6,831 patients. Results: Vitamin C supplementation improves clinical outcomes in patients with COVID-19 but does not decrease length of hospitalization. Vitamin C supplements have significantly reduces the risk of mortality by 36% and the severity of the disease by 41%.

In these studies, vitamin C was administered either as an infusion or orally. Vitamin C could therefore have its place in the treatment of COVID-19, in particular to reduce the hyper-inflammation which follows the infection and persists in the elderly, explaining many serious forms.

Vitamin C against pneumonia

Vitamin C supplementation reduces the risk of pneumonia as well as the severity of symptoms (4).

How to take vitamin C

What are the signs of a lack of vitamin C?

If scurvy is rare today, vitamin C deficiency can manifest itself in cases of malnutrition by a large fatiguea depression and connective tissue abnormalities: gingivitisinternal bleeding, healing defects, etc. In children, bone growth can be impaired (5).

How much vitamin C per day?

In France, ANSES (national agency for food, environmental and occupational health safety) has set the nutritional reference for the population (RNP) for vitamin C at 110 mg per day for adults. Our body is unable to produce vitamin C. It must therefore be found in food or food supplements.

Vitamin C: in which foods?

Vitamin C can be provided by vegetables (cabbage, pepper, etc.), and different fruits such as berries, citrus fruits, red fruits (see figure). To reach the dose of 110 mg per day, for example, you must eat three oranges or two kiwis per day. It is therefore entirely possible to meet your daily vitamin C needs as part of a balanced diet.

Vitamin C supplements

To increase your intake, particularly in the event of fatigue or colds, or in the event of insufficient vitamin intake, you can resort to supplements, in the form of a cure for example. In The guide to antioxidant supplementsDaniel Sincholle and Claude Bonne recommend a supplement of 200 to 500 mg of vitamin C per day. For them, it is “a good basis for preventing many diseases and stay fit and in good health, especially after the age of 40. If there is a threat of flu or cold, you can supplement at a rate of 2 g per day for 48 hours.”

Be careful with multivitamin-multimineral supplements where vitamin C could end up with copper and iron because “Copper and iron in the presence of vitamin C can lead to the production of dangerous free radicals.”

Vitamin C exists in supplements in different forms:

natural vitamin C which can be extracted from fruits (oranges, lemons, acerola, etc.);
synthetic vitamin C (produced in the laboratory).

“In terms of health benefits, we know that vitamin C returned to its natural environment is more available to the body and more slowly absorbed than synthetic vitamin C aloneexplain Daniel Sincholle and Claude Bonne. Concretely, the differences observed between the two forms of vitamins are not very significant and are probably of no consequence in terms of health benefits.

Side effects and risk of overdose

Please note, vitamin C supplements in doses greater than 2 g per day could, according to certain studies, promote kidney stones in certain predisposed people.

It is recommended not to exceed 2 g of vitamin C per day over a prolonged period. Excessive intake of vitamin C (more than 3 g per day) can cause diarrhea, bloating, heartburn and nausea.