Many nutrients and elements influence the resilience of the human immune system. Among these, vitamin C, vitamin D and zinc stand out as some of the most important, with immunomodulatory functions as well as a role in maintaining epithelial and endothelial barriers, including lung tissue. With the Covid-19 pandemic currently showing no signs of abating, there has been much speculation about whether they could play a role in both the prevention and treatment of the virus.
Around the world, multiple studies are now ongoing to determine whether supplements of common nutrients and vitamins could help ward off infections of SARS-CoV-2, the coronavirus that causes Covid-19 or even treat the disease by limiting its inflammatory effect on the lungs and other organs. What is clear is that the greatest benefit of supplements is likely for people who suffer from specific nutrient deficiencies.
Despite its name, vitamin D is actually a hormone produced within the body which regulates over 200 genes in different cell types. Vitamin D is known to help keep bones strong and enhances the functionality of immune cells. Vitamin D may also help control inflammatory responses generated by Covid-19 by downregulating pro-inflammatory cytokines. The high mortality rate and long-term symptoms of Covid-19 are associated with so-called “cytokine storms”, which are caused by an overreaction of the body’s immune system.
Preliminary data from patients with Covid-19 suggests a relationship between vitamin D deficiency and the severity of cytokine storms, indicated by high serum levels of C-reactive protein (CRP), which rises when there is inflammation in the body. A study published in May 2020 found a link between low levels of vitamin D and higher percentages of Covid-19 cases and mortality in Europe, while a study published in September 2020 reported that hospitalized Covid-19 patients who had sufficient levels of vitamin D showed less severe symptoms and lower mortality. Boston University School of Medicine’s Dr. Michael Holick, senior author of the second study, explained in a press release:
“Our study provides direct evidence that vitamin D sufficiency can reduce Covid-19 complications, including cytokine storms and ultimately death.”
Vitamin C (or ascorbic acid) is a water-soluble micronutrient with antioxidant properties that maintains the resistance of the epithelial barrier to disease and supports the function of both innate and adaptive immune systems. Research suggests that oral vitamin C may reduce the incidence and duration of respiratory infections, while intravenous vitamin C may reduce mortality and time on mechanical ventilation for severe respiratory infections, including Covid-19.
In early 2020, seven U.S. doctors joined together to promote a treatment for seriously ill Covid-19 patients involving the intravenous combination of vitamin C, corticosteroids and the anticoagulant heparin (called the “MATH+ Protocol“). Dr. Paul Marik, MD, Professor of Internal Medicine and Chief of Pulmonary and Critical Care Medicine at the Eastern Virginia Medical School, conceived of the treatment as a way to mitigate runaway inflammation in the lungs, which is the principal cause of mortality in most Covid-19 patients.
“It’s not the Covid-19 virus that kills patients, it’s their response to it,” said Marik, describing the excessive inflammation that results from an overly aggressive immune system (cytokine storms).
Dr. Marik and his medical partners propose the use of vitamin C and steroids, which both have potent anti-inflammatory properties, to control cytokine storms. While the treatment remains controversial, it is not unconventional—vitamin C has been used widely in the Chinese treatment of Covid-19 patients. Various clinical trials involving vitamin C injections are now ongoing in different countries across the globe.
The Zinc Link
It’s not only vitamins C and D which could play an important role in boosting the body’s defenses against Covid-19 and minimizing damage following infection. Zinc is essential for maintaining a robust immune system, with an important role in the maintenance, development and activation of cells during innate and adaptive immune responses. It also plays a role in the integrity of epithelial barriers, which are essential in order to prevent the entry of pathogens into the body.
Claude Laggard, a French medical biologist and founder of the Nutria Laboratory, is surprised that the link between zinc deficiency and severe Covid-19 symptoms has so far been underexplored and he carried out a study that highlights the role that zinc plays in our immune systems. Laggard said:
“Zinc plays a fundamental role in the body and is involved in multiple biological reactions. Our body doesn’t need a lot of zinc, but since there are numerous food interferences, its presence in optimal concentrations is not guaranteed. Zinc deficiency affects up to a quarter of all people in Western countries and I am convinced that the majority of Covid-19 sufferers are deficient.”
The role of zinc in immune system pathways is complex, since it participates both in pro-inflammatory and regulatory pathways. Zinc deficiencies have been associated with higher IL-6 responses (IL-6 is an interleukin that plays an important role in severe lung damage caused by Covid-19). Zinc also inhibits SARS-Cove RNA polymerase and its ability to replicate. Research presented at the 2020 ESCMID Conference on Coronavirus Disease suggests that lower levels of baseline plasma zinc are associated with poorer survival outcomes in severe Covid-19 patients. The research, which was led by Dr. Roberto Güerri-Fernández, of Barcelona’s Hospital Del Mar, involved a retrospective analysis of Covid-19 patients admitted to a university hospital during the spring of 2020. After adjusting for variables such as age, sex, and severity, each unit increase in the level of zinc in the patient’s blood at the time of admission correlated with a 7% lower risk of dying after admission.
“Lower zinc levels at admission correlate with higher inflammation in the course of infection and poorer outcome,” said a member of the team led by Dr. Güerri-Fernández.