With the approach of winter, Vitamin C has always been thought to help against the cold virus but, due to its long history as a remedy against the common cold and other respiratory infections, recently it has been proposed as a potential therapeutic agent against COVID-19 disease, It can be obtained daily by consuming fruits and vegetables, but you can also acquire it through vitamin C supplements. This vitamin plays an important role in the health of the immune system due to its effect on certain immune cells. It has anti-inflammatory properties that modulate the production of cytokines, decreasing histamine levels. This improves the differentiation and proliferation of T and B lymphocytes, increasing antibody levels and protecting against the effects related to the pathology of COVID-19.

As evidenced by lower concentrations in leukocytes and lower concentrations of vitamin C in urine. the body uses Vitamin C during viral infections and once the infection is overcome, the levels return to normal. It has been shown that as little as 0.1 g per day of vitamin C can maintain normal plasma levels of this nutrient in healthy individuals, but higher doses (at least 1-3 grams per day) are required for critically ill patients in the ICU.


Specifically, vitamin C deficiency appears to be common among COVID-19 patients. COVID-19 is also associated with the formation of microthrombos and coagulopathy that contribute to its characteristic pulmonary pathology, but these symptoms can be improved with early infusions of vitamin C that inhibit the expression of P-selectin on the endothelial surface and platelet-endothelial adhesion.

Intravenous vitamin C also reduced Ddimer levels, which are remarkably high in COVID-19 patients, as demonstrated by a study with 17 patients. Therefore, there is evidence to suggest that vitamin C status and its complementary administration may be relevant to outcomes in patients infected with COVID-19.

A recent meta-analysis found consistent support for regular vitamin C supplementation that reduces the duration of the common cold, but vitamin C supplementation (>200 mg) failed to reduce the incidence of colds.

On the other hand, individual studies have found that vitamin C reduces patients’ susceptibility to lower respiratory tract infections, such as pneumonia. Another meta-analysis showed that, in twelve trials, vitamin C supplementation reduced the length of stay of patients in intensive care units (ICUs) by 7.8% (95% CI 4.2% to 11.2%; p=0.00003).

In addition, high doses (1-3 g/day) significantly reduced the length of ICU stay by 8.6% in six trials (p=0.003). It should be added that vitamin C shortened the duration of mechanical ventilation by 18.2% in three trials in which patients required intervention for more than 24 hours (95% CI 7.7% to 27%, p=0.001). Despite these findings, an RCT of 167 patients known as CITRUS ALI failed to show a benefit from a 96-hour vitamin C infusion to treat acute respiratory distress syndrome (ARDS).

Trials are ongoing with emphasis on the use of intravenous vitamin C for hospitalized patients. In fact, the first trial to publish its results took place in Wuhan, China, where the administration of 12 g/12 h of intravenous vitamin C over 7 days in 56 critically ill patients with COVID-19 resulted in a promising reduction in mortality at 28 days (p=0.06) in the univariate survival analysis. A significant decrease in IL-6 levels was also reported on day 7 of vitamin C infusion (p=0.04).

Several additional studies being conducted in Canada, China, Iran, and the U.S. will be able to provide additional information on whether vitamin C supplementation affects COVID-19 outcomes on a larger scale.

Author: Seb

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