High doses of vitamin C being studied to treat COVID-19 may benefit some populations, but researchers exploring its aging potential say key factors for efficacy include levels of the natural transporter needed to get the vitamin inside the cells.
Age, race, gender, as well as the expression levels and genetic variations of those vitamin C transporters that make them less efficient, all can be factors in the effectiveness of vitamin C therapy against COVID-19 and other diseases, researchers of the Medical College of Georgia Center for Healthy Aging Report in a journal comment Aging and disease.
Researchers recommend that these factors be considered in the design and execution of clinical trials, and when study results are analyzed, for COVID-19 and other conditions, says Dr. Sadanand Fulzele, researcher on aging and corresponding author of the paper. .
The new nature and lack of immunity against the coronavirus have prompted people to seek effective treatments for COVID-19 around the world, they write. This includes the reuse of drugs with known safety profiles, including vitamin C, an established immune system enhancer and antioxidant, which made it a logical choice to explore in COVID-19. Both strategies are needed in response to infection with the novel coronavirus to ensure a strong immune response to prevent the virus from replicating in the body and to avoid the excessive and destructive immune response that the virus itself can generate if it does.
At least 30 clinical trials are ongoing in which vitamin C, alone or in combination with other treatments, is being evaluated against COVID-19, some with doses up to 10 times the recommended 65 to 90 milligrams per day of the vitamin. C.
Factors such as whether or not vitamin C can enter the cell are likely a problem in the efficacy that therapies ultimately show, says Dr. Carlos M. Isales, co-director of the MCG Center for Healthy Aging and head of the MCG division of Endocrinology, Diabetes and Metabolism.
In fact, without adequate transporters on the cell surface to pass the water-soluble vitamin beyond the lipid layer of cell membranes, particularly high doses can allow the vitamin to cluster around the outside of the cells where it actually begins to produce oxidants, such as oxygen damage. reactive species, rather than helping to eliminate them, says Isales, co-author of the study.
“We believe it is important to consider the expression of teleportation,” says Fulzele.
They suspect that low expression of the transporter is a factor in the conflicting results of using vitamin C in a variety of other conditions. Clinical trials of osteoarthritis, for example, an autoimmune disease in which a misdirected immune system is attacking the joints, has had mixed results, says Fulzele. However, its use in other virus-induced problems, such as life-threatening sepsis, has shown benefits in reducing organ failure and improving lung function in acute respiratory distress syndrome, which is also a major cause of disease and death with COVID-19.
At the moment theirs Aging and disease article has been published, no studies have yet been published on the efficacy of ongoing high-dose intravenous vitamin studies for COVID-19.
Fulzele, who works on vitamin C in aging, and others have shown that some conditions, such as osteoarthritis and even normal aging, are associated with significant downregulation of at least one subtype of the vitamin C transporter.
In fact, part of the paradox and concern with COVID-19 is that people most at risk have mostly lower levels of vitamin C before they get sick and fewer transporters to allow the vitamin to be of benefit if they get more. Fulzele says.
Many of those most at risk of COVID-19, including older, black, male individuals and individuals with chronic medical conditions such as osteoarthritis, hypertension and diabetes tend to have lower levels of vitamin C, another reason. vitamin C therapy would be considered a reasonable treatment, says Isales. The researchers also note that patients can develop a vitamin C deficiency during their COVID-19 disease because, during an active infection, vitamin C is consumed at a faster rate. Insufficient levels can increase the damage caused by an overzealous immune response.
Although not done routinely, today transporter expression can be measured using PCR technology, a method also used for the novel coronavirus and for influenza testing. Although increasing transporter expression is not yet feasible in humans, one of Fulzele’s many research goals is to find a drug or other method to directly increase expression, which should improve the health of older and older individuals. with other medical conditions that compromise those levels.
He notes that the reduced transporter levels that occur naturally with age are a factor in the reduced immune function that typically also accompanies aging. This means that even when a 60-year-old and a 20-year-old both have a healthy diet in which they consume similar and sufficient amounts of vitamin C, the vitamin is not as effective in boosting the immune response of the older individual. Reduced immune function in older individuals is known to expose them to an increased risk of problems such as cancer and COVID-19.
Low vitamin C levels have also been correlated with higher mortality in older individuals from causes such as cardiovascular disease. High oxidative stress, a major factor in conditions such as cardiovascular disease and aging and now COVID-19, is also associated with significantly reduced expression of the vitamin C transporter.
Isales and Fulzele doubt that taking a lot of vitamin C is a good preventive strategy against COVID-19, except in those individuals with a known deficiency.
Vitamin C is an essential vitamin, which means that people must consume it in their food or supplements. Foods naturally rich in vitamin C include oranges, potatoes, tomatoes, broccoli, and Brussels sprouts. The different roles of the vitamin in the body also include the formation of blood vessels, collagen and cartilage.
Gregory Patterson, a medical student who worked with Fulzele during the summer between his first and second years of medical school as part of MCG’s medical scholars program, is the first author of the study. The research was partly supported by the National Health Institutes.
Read the full study here.