Vitamin D and COVID-19: Does Lack of Vitamin Connect to Virus Severity?

Guest Author: Dr. Helen Whitby, Technical Specialist

Recent studies have started showing that in countries where natural sunlight is lower, there is an increase in vitamin D deficiencies. This makes sense as during lockdown and Safe at Home orders there is less opportunities for exposure to natural light. Researchers are find that this could have led to more severe inflammatory responses in COVID-19 patients, which has prompted the analysis of researchers to look into the connection between levels of vitamin D and COVID-19 severity.

A study done at Trinity College in Ireland compared mortality rates from the southern hemisphere with the countries in the northern hemisphere and found a clear link showing a higher mortality rate when insufficient sunlight was available to offer adequate vitamin D.1 These studies suggest there is a possible role for vitamin D and COVID-19 in determining the outcome of the virus.

When researching mortality rate of COVID-19 patients they observed anomalies associated with the Nordic countries where sunlight is still at a low level but mortality rates were more consistent with countries from the Southern Hemisphere. This was attributed to the widespread use of vitamin D supplementation leading to an overall reduction in the vitamin D deficiencies in these countries leading to lower mortality rates when supplementation was used.

The evidence showed that although it is unlikely vitamin D can protect against infection it is effective in reducing the cytokine storm which leads to acute respiratory distress commonly attributed to mortality from the disease.

Many governments are now recommending the use of supplementation to support patients at risk from SARS-CoV-2 infection stating “supplementation is the best means to ensure sufficient vitamin D blood levels during a time where outdoor activity is limited”. General guidelines suggest if you choose to take a supplement the following levels are appropriate.

  • Children (up to 1 year old) – 8.5-10ug / day
  • Children (1-10 years old) – up to 10ug / day
  • Adults  –  10ug / day

Even prior to this research being published the consumption of dietary supplements had become a growing trend worldwide with many individuals looking to supplement their diet to improve health.

Vitamin D is a fat-soluble vitamin that has been known for its ability to enhance intestinal absorption of calcium, iron, magnesium, phosphate, and zinc. The most important vitamin D compounds are ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3) and these can be found in over the counter dietary supplements although many may only add the vitamin D3 form. As part of the Quality Assurance (QA) process, dietary supplement manufacturers must quantify the components on the label claim and resolution of each component is critical. The use of the unique selectivity of the 2.6 µm Biphenyl Core-shell stationary phase offers baseline resolution of both vitamin D2 and D3 in under 10 minutes offering efficient rapid analysis of vitamin D in dietary supplements with a single isocratic method.3


  1. Aliment Pharmacol Ther. 2020;00:1-4

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