Could low vitamin D levels increase long Covid risk?

The potential relationship between vitamin D levels and the risk of developing long Covid is gaining increasing attention in the scientific community.

A recent study presented at the 25th European Congress of Endocrinology in Istanbul suggests that people who have had Covid-19 should monitor their vitamin D levels closely, as low levels may be linked to a higher risk of long Covid.

Long Covid, also known as post-Covid-19 syndrome, is a relatively new health concern that emerged during the global pandemic.

The condition is characterised by the lingering effects of Covid-19, persisting for more than 12 weeks after the initial infection.

It is estimated that 50 per cent to 70 per cent of patients who were admitted to hospital due to Covid-19 could be affected.

Despite its prevalence, there is still much to understand about long Covid and the factors that may exacerbate its symptoms.

Vitamin D deficiency has been identified as a risk factor for severe outcomes in Covid-19 patients admitted to hospital, including the need for intubation and mechanical ventilation, and even death. However, its role in long Covid has been largely unexplored until now.

The study, which was supported by Abiogen Pharma SpA, was conducted by researchers from the Vita-Salute San Raffaele University and IRCCS San Raffaele Hospital in Milan.

The team examined 100 patients aged 51 to 70, some with long Covid and others without. They measured the patients' vitamin D levels at two points: when they were first admitted to hospital for Covid-19 and six months after discharge.

The findings revealed that patients with long Covid had lower levels of vitamin D compared to those without the disease.

This difference was particularly pronounced in patients who reported symptoms of “brain fog” — confusion, forgetfulness and poor concentration — at the six-month follow-up.

Only patients who had been admitted to hospital for Covid-19 but who had not required intensive care were included in the study. Those with bone conditions were excluded.

The two groups of patients, those with and without long Covid, were matched in terms of age, sex, pre-existing chronic diseases and Covid-19 severity.

“Previous studies on the role of vitamin D in long Covid were not conclusive mainly due to many confounding factors,” explained lead investigator Andrea Giustina.

“The highly controlled nature of our study helps us better understand the role of vitamin D deficiency in long Covid, and establish that there is likely a link between vitamin D deficiency and long Covid.”

While the findings are promising, Dr Giustina stresses that larger studies were needed to validate the link. The research team is now focusing on investigating whether vitamin D supplements could potentially reduce the risk of long Covid.

“Our study shows that Covid-19 patients with low vitamin D levels are more likely to develop long Covid but it is not yet known whether vitamin D supplements could improve the symptoms or reduce this risk altogether,” he noted.

This continuing research highlights the importance of understanding the role of vitamin D in both acute Covid-19 cases and the post-recovery phase.