CORONAVIRUS patients severely deficient in vitamin D are up to twice as likely to die as those with healthy levels, an international study has found.

The research team conducted a statistical analysis of data from hospitals across China, France, Germany, Italy, Iran, South Korea, Spain, Switzerland, the United Kingdom and the United States.

They noted patients from countries with high mortality rates, such as the UK, Italy and Spain, had lower levels of vitamin D compared to those in countries that were not as severely affected.

The research was led by Vadim Backman, professor of biomedical engineering at North Western University in the United States.

He and his team examined vitamin D levels after noticing unexplained differences in Covid-19 mortality rates from country to country. Some experts believed differences in healthcare quality, age distributions in population, testing rates or different strains of the coronavirus might be responsible, but Backman was not convinced.

“None of these factors appears to play a significant role,” Backman told Science News, an international research news publication.

“The healthcare system in northern Italy is one of the best in the world. Differences in mortality exist even if one looks across the same age group.

“And, while the restrictions on testing do indeed vary, the disparities in mortality still exist even when we looked at countries or populations for which similar testing rates apply. Instead, we saw a significant correlation with vitamin D deficiency.”

Backman and his team discovered a strong correlation between vitamin D levels and cytokine storm – a hyper-inflammatory condition caused by an overactive immune system – as well as a correlation between vitamin D deficiency and mortality.

“Cytokine storm can severely damage lungs and lead to acute respiratory distress syndrome and death in patients,” said Ali Daneshkhah, who worked with Backman on the research study.

“This is what seems to kill a majority of Covid-19 patients, not the destruction of the lungs by the virus itself.

“It is the complications from the misdirected fire from the immune system.”

Backman believes it is the benefit of vitamin D in supporting the immune system’s functioning that helps patients successfully fight the virus. “Our analysis shows that it might be as high as cutting the mortality rate in half,” Backman said. “It will not prevent a patient from contracting the virus, but it may reduce complications and prevent death in those who are infected.”

He added the correlation might help explain the many mysteries surrounding Covid-19, such as why children are less likely to die. Children do not yet have a fully developed acquired immune system, which is the immune system’s second line of defence and more likely to overreact. “Children primarily rely on their innate immune system,” Backman said. “This may explain why their mortality rate is lower. “

He added: “It is clear that vitamin D deficiency is harmful, and it can be easily addressed with appropriate supplementation. This might be another key to helping protect vulnerable populations, such as African-American and elderly patients, who have a prevalence of vitamin D deficiency.”

The Scottish Government recommends everyone should consider taking a daily supplement containing 10 micrograms (mcg) of vitamin D .