May 16, 2023 – A brand new study shows that patients with long COVID-19 had lower vitamin D levels than patients who had recovered from COVID-19, suggesting that taking vitamin D supplements may help prevent or alleviate the debilitating disease.
The lower vitamin D levels in patients with long COVID – in whom the results of the unique COVID infection last more than 12 weeks – were most pronounced in those with “brain fog.”
These findings by Luigi di Filippo, MD, and colleagues were recently presented on the European Congress of Endocrinology in Istanbul and the study also appeared within the Journal of Clinical Endocrinology and Metabolism.
“Our data suggest that vitamin D levels should be checked in COVID-19 patients after hospital discharge,” wrote the researchers from San Raffaele Hospital in Milan, Italy.
The researchers highlighted as a strength that this controlled study included patients with multiple symptoms of Long COVID and had an extended follow-up period than most previous studies (6 months versus 3 months).
“The highly controlled nature of our study helps us better understand the role of vitamin D deficiency in Long COVID and that there is likely a link between vitamin D deficiency and Long COVID,” said the study's lead writer, Dr. Andrea Giustina, in a press release.
However, he said: “It is not yet known whether vitamin D supplements could relieve symptoms or reduce the risk overall.”
Supplement in case of deficiency?
Amiel Dror, MD, PhD, who has a related study The study showed that individuals with vitamin D deficiency usually tend to develop severe COVID, agreed.
“The novelty and significance of this [new] “The importance of this study is that it expands our current understanding of the interplay between vitamin D and COVID-19 and extends beyond the acute phase of the disease,” said Dror, of the Azrieli Faculty of Medicine at Bar-Ilan University in Safed, Israel.
“It is remarkable how vitamin D levels continue to influence health even after patients have recovered from the initial infection,” he said.
“The results certainly strengthen the argument for conducting a randomized controlled trial,” he said, “which would allow us to conclusively determine whether vitamin D supplementation can effectively reduce the risk or severity of Long Covid.”
“In the meantime,” Dror said, “given the safety profile of vitamin D and its broad health benefits, it may be prudent to test vitamin D levels in patients admitted with COVID-19. If low levels are found, supplementation could be considered.”
“It is important to note, however, that this should be done under medical supervision,” he said, “and further studies are needed to determine the optimal timing and dosage of supplementation.”
Vitamin D deficiency and risk of long-COVID disease
Low vitamin D levels are related to a better likelihood of requiring mechanical ventilation and a worse probability of survival in COVID patients. However, the chance of “long COVID” related to vitamin D is poorly understood.
The researchers analyzed data from adults aged 18 years and older who were admitted to San Raffaele Hospital with a confirmed COVID diagnosis and discharged in the course of the first wave of the pandemic from March to May 2020 and were followed up at a follow-up clinic six months later.
Patients were excluded in the event that they were admitted to the intensive care unit during their hospital stay or if medical data or blood samples for vitamin D levels were missing at admission and at 6-month follow-up.
Using guidelines from the UK National Institute for Health and Care Excellence, Long COVID was defined because the presence of at the very least two or more of 17 symptoms that weren’t present before COVID infection and might be attributed only to that acute illness.
The researchers identified 50 patients with long COVID on the 6-month follow-up and compared them with 50 patients without long COVID at the identical time point based on age, gender, other medical conditions, and wish for noninvasive mechanical ventilation.
Patients were on average 61 years old and 56% were men; 28% were on a ventilator during their hospital stay for COVID.
The commonest symptoms after 6 months in patients with Long COVID were weakness (38%), bad taste within the mouth (34%), shortness of breath (34%) and lack of sense of smell (24%).
Most symptoms were related to the cardiovascular system (42%), well-being (42%) or the senses (36%). Fewer patients had symptoms related to neurocognitive impairment (headache or brain fog, 14%), ear, nose and throat (12%) or the gastrointestinal tract (4%).
Patients with Long COVID had lower average vitamin D levels than patients without Long COVID, and vitamin D levels were significantly lower in patients with symptoms corresponding to headaches or brain fog.
The researchers used an evaluation method called multiple regression, which showed that vitamin D was the one variable significantly related to Long COVID at follow-up.
The findings “strongly support the clinical utility of vitamin D assessment as a potential modifiable pathophysiological factor underlying this critical global health problem,” the researchers concluded.