Researchers from the University of California, Davis have observed that individuals taking very high doses of folic acid may face an increased risk of both contracting COVID-19 and experiencing a fatal outcome. The findings were reported in the BMJ Open journal.
The study analyzed medical records from more than 380,000 adults in the United Kingdom who were 45 years or older. Among over 26,000 people infected with the coronavirus, 820 fatalities occurred. The data showed that those prescribed folic acid at five times the permitted limit had about a 1.5-fold higher chance of infection and roughly a 2.6-fold higher risk of death when compared with a control group. It should be noted that blood folate levels were not measured in this cohort.
Separately, researchers found that methotrexate, a medication that reduces folic acid levels, did not appear to increase the risk for COVID-19 patients. This detail helps clarify the potential safety profile of folate-lowering therapies during infection.
The implications of these results may influence treatment decisions for patients who rely on folic acid supplementation. While folic acid is essential in many contexts, clinicians should exercise caution when prescribing high-dose regimens. The generally accepted safe upper limit for folic acid is 1 milligram per day.
In another related line of inquiry, a 2021 study published in Nature Communications indicated that the SARS-CoV-2 virus may utilize human folic acid during replication. This suggests that the virus could be affected by both folic acid itself and inhibitors that target folate pathways, including methotrexate. These insights prompted further examination of how folic acid intake might relate to clinical outcomes in COVID-19 patients.
Low folic acid levels in pregnant women have been linked with a higher risk of birth defects in newborns. Folic acid, also known as vitamin B9, is prescribed for several conditions, including the management of sickle cell anemia and for individuals taking anticonvulsants. Some patients receiving methotrexate, a drug used for certain cancers and autoimmune diseases, also take folic acid to mitigate treatment-related side effects.
Overall, folic acid remains a vital nutrient for development and health, but the emerging evidence underscores the need for careful dosing and individualized medical guidance, especially in the context of infection risk and ongoing treatments.