Can vitamin D protect against covid-19?

The status of vitamin D in Covid has been changing frequently during the past year and especially the past few months. The NICE, CDC guidelines states that is insufficient evidence and specifically NICE guidelines stated NOT to ‘not use vitamin D to treat COVID-19 except as part of a clinical trial ‘ in July 2022. However evidence changes fast with RCTs and Meta-Analysis being published this month.

What is known about Vitamin D

Vitamin D is an important regulator of calcium balance. In addition, it has important effects on the immune system, directly inducing antimicrobial peptides at mucosal surfaces and modulating the function of T cells. Observational studies from the pre-pandemic era found an association between low levels of vitamin D and an increased risk of respiratory tract infections. Results from randomised controlled trials were mixed, but two large meta-analyses found some evidence of a protective effect of vitamin D supplementation against respiratory tract infections, particularly in vitamin D deficient individuals.

Could vitamin D help protect against covid-19?

Two new trials find no effect – LINK1 LINK2 However, the null findings of the studies should be interpreted in the context of a highly effective vaccine rolled out during both studies.

Vaccination is still the most effective way to protect people from covid-19, and vitamin D and cod liver oil supplementation should not be offered to healthy people with normal vitamin D levels. Importantly, these new trials remain compatible with the two large meta-analyses suggesting that vitamin D supplementation may be beneficial for vitamin D deficient individuals.

A pragmatic approach for the clinician could be to focus on risk groups; those who could be tested before supplementation, including people with dark skin, or skin that is rarely exposed to the sun; pregnant women; and elderly people with chronic diseases. For those with inadequate vitamin D levels (<50 nmol/L), supplementation with 1000-2000 IU/day could be a safe, simple, and affordable way to restore vitamin D levels, improve bone health, and take advantage of any possible protective effect against respiratory tract infections.

In our Sri Lankan context ordering vitamin D levels incurs a huge cost and for most persons will not be affordable. The decision is ours: Firstly that taking into consideration of the patient’s context, using our clinical expertise regarding the patients’ comorbidities and the current best research evidence. This is what evidence based practice means.

Read the complete BMJ editorial


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