Vitamin D deficiency linked to poorer outcomes in COVID-19 patients

Research has shown that in some people, COVID-19 triggers an overwhelming immune response. This can worsen the outcome for these patients, as an over-the-top immune response can lead to excessive production of cytokines (a type of immune cells) which can seriously harm the body.

Indeed, scientists around the world are still trying to figure out if the cause of death in COVID-19 is usually the viral infection itself or the exuberant response to the infection mounted by our immune system (cytokine storm).

Given the link between vitamin D and immune response, researchers at the Anglia Ruskin University (ARU), UK, and Queen Elizabeth Hospital King’s Lynn NHS Foundation Trust, UK, set out to understand if vitamin D deficiency could be linked to poorer outcomes in COVID-19 patients.

To study this, they compared data on COVID-19 cases and deaths in 20 European countries to previously collected data on vitamin D deficiency in these countries. They found a correlation: in Italy and Spain, where mortality was high, the incidence of vitamin D deficiency was also high. Conversely, where people had adequate levels of vitamin D, like in the Scandinavian countries, mortality was lower.

The authors hypothesized that vitamin D may play a protective role by enhancing the levels of ACE2 receptors in the body, which in turn has been shown to protect against acute lung injury.

The study authors added that vitamin D levels are just one of the factors that may influence outcomes. For example, in Italy, Spain and Switzerland, the people with low vitamin D levels also tend to be elderly. And research has already shown that the elderly are more likely to fall severely ill and die if they contract the infection, compared with people under 60 years of age.

Another study, which was done at Northwestern University and Boston Medical Center, US, has indicated that patients with severe vitamin D deficiency are at a higher risk (17.3%) of contracting severe COVID-19, compared with patients who have normal levels of the vitamin (14.6%). The study is yet to be peer-reviewed and is in the pre-print phase.

Anywhere between 80% and 90% Indians have a vitamin D deficiency. Researchers point out that this could make us more prone to autoimmune diseases, heart disease, cancer, depression and upper respiratory tract infections, among other illnesses. 

The recommended daily allowance of vitamin D for Indian adults is 600-800 IU (international units). We get our vitamin D from foods and supplements. In addition to this, our skin makes vitamin D when we go out in the sun. Darker skin and old age, however, reduce the skin’s capability to make this fat-soluble vitamin.

COVID-19 is a viral infection that starts in the upper respiratory tract, before moving to the lower respiratory tract. In India, the rate of infection is currently in check because of extreme measures like a nationwide lockdown.

However, as the lockdown lifts and we resume life as best as we can during a pandemic, we will have to become more conscious about what we eat, how we live and the preventive health measures we take. Adding more vitamin D-rich foods like oily fish, egg yolks and mushrooms to our diet or taking vitamin D supplements could be a step in the right direction.