Over the last several months, scientists and medical researchers around the world have been pouring countless hours into COVID-19 research, trying to learn everything they can about the virus. How it travels, how long it survives on surfaces, and how it attacks the body are just a few of the questions that needed to be answered. Of course, the main focus of most of the COVID-19 research has been on how to treat and prevent the virus. While there is currently no vaccine or treatment, there is a new study linking vitamin D to a lower coronavirus death rate.
The Vitamin D Study
The research team was led by Dr. Lee Smith of Anglia Ruskin University (ARU) and Dr. Petre Cristian Ilie, lead urologist of Queen Elizabeth Hospital King’s Lynn NHS Foundation Trust and published in the journalAging Clinical and Experimental Research.
The team collected data from twenty European countries to describe the average vitamin D levels of that population, as well as the morbidity and mortality statistics for each country . They found that countries that have lower than average Vitamin D levels had a higher COVID-19 mortality rate. The study cites Italy and Spain, both of which have lower than average vitamin D status and experienced high COVID-19 mortality rates. In comparison, other Northern European countries, which have higher than average vitamin D status due to consumption of cod liver oil and vitamin D supplements, and have had lower COVID-19 mortality rates .
Vitamin D and Respiratory Infections
Cytokines are proteins that help with cell-to-cell communication during an immune response and help direct cells toward sites of inflammation, infection, or trauma. A cytokine storm is when this immune response gets out of control and begins attacking healthy cells in other parts of the body . This is what has occurred in many coronavirus patients.
Vitamin D seems to have an effect on immune cells that make them less inflammatory, which prevents this “overreaction” from happening .
More Vitamin D Research
The team from the UK is not the only one who is investigating the correlation between vitamin D status and COVID-19 mortality. A study conducted by Northwestern University determined that 17 percent of individuals with low vitamin D status would develop a severe COVID-19 infection, while only 14 percent of those with adequate Vitamin D would become severely ill .
Indonesian researchers studied 780 COVID-19 patients and found that most of the patients who died had lower than average Vitamin D levels, and a group of Irish researchers also found a correlation between low vitamin D status and COVID-19 mortality .
It is still unclear, however, whether or not improving a patient’s vitamin D status can improve the outcome for a patient who already has the virus. There is some research from the University of Southeastern Philippines suggesting that vitamin D supplementation could possibly improve clinical outcomes of patients infected with COVID-19, however, the paper has not yet been peer-reviewed and so no definitive conclusions can be drawn .
There has, however, been other research that has not found a link between vitamin D status and COVID-19 mortality, and so more research is needed to evaluate the role of vitamin D in the prevention of viruses .
Vitamin D Recommendations
At least 20 nanograms of vitamin D per millilitre of blood is needed to maintain bone health, and if you have under 12 nanograms per millilitre, you are deficient .
Researchers are not recommending, however, that everyone go out and get a vitamin D supplement.
“While I think it is important for people to know that vitamin D deficiency might play a role in mortality, we don’t need to push vitamin D on everybody,” said Northwestern’s lead researcher, Vadim Backman. “This needs further study, and I hope our work will stimulate interest in this area.” 
Taking too much vitamin D can lead to Vitamin D toxicity, which can cause harm in your body. While it is one of the rarest medical conditions in the world, it is still something to be aware of.
Dr. David Seres, director of medical nutrition at Columbia University Irving Medical Center, says that vitamin D has been promoted as a cure for several serious illnesses, but wants people to understand that vitamin D won’t cure the coronavirus.
“There is no data that the effect of sun exposure on vitamin D levels, or supplementation of vitamin D, has any impact on whether you are susceptible to coronavirus infection, or on the severity of the illness if you are infected,”he said .
The Institute of Medicine recommends the following dosages for vitamin D supplementation:
- children less than one year old take 400 international units (IUs) of vitamin D per day
- People aged one to 70 years old take 600 IUs per day
- Adults over 70 take 800 IUs per day 
Dr. Seres recommends that you consult your doctor first before beginning any kind of supplementation regime.