- Some research suggests vitamin D insufficiency has ties to worse COVID-19 outcomes.
- A new study that considers pre-infection vitamin D levels confirms their link to severe COVID-19.
- The researchers say their findings do not necessarily imply that vitamin D treatment will impact COVID-19 outcomes, although they suggest maintaining normal levels is wise.
Having sufficient levels of Vitamin D is important for promoting healthy bones and teeth. Too little of it has links to diabetes, autoimmune, cardiovascular, and infectious diseases. Among these is COVID-19.
Researchers at Bar Ilan University and the Galilee Medical Center in Israel have released a study that examines the links between Vitamin D levels and the severity of COVID-19 for 253 people admitted to the hospital. with COVID-19 The researchers found records indicating their vitamin D levels before they acquired a SARS-CoV-2 infection and went to the hospital.
The study concluded that people with insufficient pre-infection levels of vitamin D were 14 times more likely to develop severe COVID-19 than those with high vitamin D levels.
The study appears in PLOS ONE.
Timing counts
The study’s lead author is Dr. Amiel Dror, a Galilee Medical Center and Bar Ilan researcher. He told Medical News Today why he suspects previous research investigating the connection between vitamin D insufficiency and COVID-19 has been inconclusive and even contradictory:
“The majority of the studies (at least at the early pandemic stage) have tackled vitamin D in the context of acute viral infection. These studies aimed to assess whether low vitamin D in the presentation to the hospital is associated with COVID-19 disease outcome. Vitamin D measurement [during] a patient’s COVID-19 illness represents the vitamin D level at a specific time point.”
Dr. Dror said that when one measures the vitamin D levels of a person who already has SARS-CoV-2 infection, it is difficult to know if COVID-19 is suppressing vitamin D or if the lack of it aggravates the infection.
Dr. Dror explained that “vitamin D undergoes activation in the liver to become active. Many COVID-19 patients suffer from an impaired liver function that abolishes the ability to activate vitamin D during the illness.”
Dr. Iacopo Chiodini, associate professor of endocrinology at Università degli Studi di Milano, Italy, told MNT that scientists have not yet established how vitamin D might help contain COVID-19 even if there is enough of it. Dr. Chiodini was not involved in the study.
Dr. Chiodini suggested vitamin D may act, for example, as a modulator of the cytokine storm that leads to lung damage and disease progression or of neutrophil activity, “thus reducing their excessive activation and recruitment into the inflamed lung.”
He also speculated that vitamin D might protect the integrity of and repair the pulmonary epithelial barrier or lower the risk of lung and systemic thrombosis seen in severe COVID-19.
Beyond that, said Dr. Chiodini:
“Vitamin D deficiency can be one indication of a wide range of chronic health conditions or behavioral factors that simultaneously increase COVID-19 disease severity and mortality risks.”
Studying vitamin D supplementation
A second area where previous research has proven inconclusive involves whether vitamin D supplementation during illness with COVID-19 has value. Dr. Dror cited one study in which patients received supplemental vitamin D approximately 10 days after the onset of COVID-19 symptoms:
“Obviously, it should be no surprise that such a late intervention would not alter the observed disease course that much. When a study aims to determine the effect of vitamin D treatment, [I] would recommend a study design with earlier intervention/treatment rather than 5-10 days after the symptoms’ onset when the body has already undergone severe distress.”
In the new study, the question remains unanswered. As Dr. Chiodini reminded MNT, “an association between pre-infection vitamin D deficiency and COVID-19 severity does not necessarily imply that vitamin D treatment will impact COVID-19 outcomes.”
One piece of the vitamin D/COVID-19 puzzle
After accounting for a variety of other possible factors, said Dr. Dror, “Vitamin D effect was so strong, and identified in each multivariate regression model we tested as the most prominent independent factor on disease severity and mortality.”
Dr. Dror noted that his study is observational and added: that “I totally agree that randomized controlled trials are crucial to showing causation” between vitamin D and COVID-19 outcomes.
He continued: “Having said that, there are many good reasons for maintaining normal vitamin D levels (bone and skeletal health, etc.) regardless of COVID-19. Therefore, If it could be beneficial to fighting the respiratory viral infection, I can’t see a reason to avoid it.”
“Altogether, I recommend that people keep their baseline vitamin D at a normal level and certainly avoid the deficiency level of 20 nanograms per milliliter (ng/ml). These recommendations already exist regardless of the COVID-19 pandemic. During this period, I would especially stick to these recommendations.”
– Dr. Dror
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