Some populations may benefit from high doses of vitamin C for the treatment of COVID-19, but researchers investigating its potential in aging claim main efficacy factors include levels of the natural transporter required to get the vitamin into the cells.

Researchers at the Medical College of Georgia Center for Healthy Aging reported in a commentary in the journal Aging and Disease that age, race, sex, as well as expression levels and genetic differences of certain vitamin C transporters that make them less functional, all may be factors in the efficacy of vitamin C therapy against COVID-19 and other diseases.

The researchers propose that these variables be considered for COVID-19 as well as other factors in the design and execution of clinical trials and when test outcomes are evaluated, says Dr. Sadanand Fulzele, an aging researcher and the corresponding author of the paper.

The novel nature and lack of coronavirus immunity have sparked a worldwide search for successful COVID-19 therapies. This entails repurposing medications with proven safety profiles, including vitamin C, a booster and antioxidant of the developed immune system, which made it a reasonable option to pursue in COVID-19.

In response to infection with the novel coronavirus, both techniques are required to maintain a robust immune response to deter the virus from replicating in the body and to prevent the over-the-top, damaging immune response that the virus itself will produce if it does.

At least 30 clinical trials are ongoing in which vitamin C is tested against COVID-19 alone or in conjunction with other therapies, some with doses of up to 10 times the recommended 65 to 90 milligrams of vitamin C daily.

Factors like whether or not vitamin C will get into the cell are likely to be a problem in the efficacy that treatments actually demonstrate, says Dr. Carlos M. Isales, co-director of the MCG Center for Healthy Aging and head of the Endocrinology, Diabetes and Metabolism Division of MCG.

In reality, especially large doses without sufficient transporters on the surface of a cell to get the water-soluble vitamin past the lipid layer of cell membranes will cause the vitamin to cluster around the outside of cells where it actually begins to generate oxidants, such as harmful reactive oxygen species, rather than helping to remove them, says Isales, a co-author of the report.

In several other factors, they believe low transporter expression is a factor in the mixed findings from the use of vitamin C. At the time of publishing of their Aging and Disease article, findings of the effectiveness of high-dose, intravenous vitamin studies for COVID-19 have not yet been published.

Many of those most at risk from COVID-19 appear to have lower vitamin C levels, particularly those who are elderly, black, male, and with chronic medical conditions such as osteoarthritis, hypertension, and diabetes, another reason why vitamin C therapy would be considered a reasonable cure.

Vitamin C is an essential vitamin, which means that through their diet or supplements, individuals have to eat it. Oranges, potatoes, onions, broccoli, and Brussels sprouts include foods naturally rich in vitamin C. The vitamin's various functions in the body can include the production of cartilage, collagen, and blood vessels.