Over 80% of the COVID-19 patients at a hospital in Spain were found to have a vitamin D deficiency, a new study notes. Men had an even higher rate of deficiency than women.

Although the sample size was fairly small (just over 200 people), it’s yet another piece of evidence suggesting that vitamin D and COVID-19 might be connected.

“We believe that vitamin D treatment should be recommended in COVID-19 patients with a deficiency since this approach might have beneficial effects,” the lead author notes.

The sunshine vitamin

Vitamin D is essentially a steroid, a hormone produced by your liver, helping to regulate the blood and immune system. An estimated 1 billion people in the world don’t have enough vitamin D in their body, either because they don’t consume a diet with sufficient vitamin D or because they don’t have enough sun exposure. This is a main difference between vitamin D and other types of vitamins: you don’t need to eat it necessarily since your body can produce it with sufficient sun exposure.

“The prevalence of vitamin D deficiency is found in 40% of European population regardless of age, ethnicity or latitude,” says study author José L. Hernández of the University of Cantabria in Santander, Spain. Although variations in serum vitamin D levels across countries are dependent on age (the elderly being the most affected by this vitamin D deficiency) and the use of vitamin D supplements or food fortification.”

Hernández analyzed data from 216 COVID-19 patients at the Hospital Universitario Marqués de Valdecilla, in northern Spain. It’s an area where 47% of the population suffers from vitamin D deficiency, Hernández tells me, but for the COVID-19 patients, the deficiency rate was 80%.

Even with such a fairly small sample size, it’s a striking result — and not the only one to point in this direction. Although the effects of vitamin D on the immune system are still debated scientifically, several studies have suggested beneficial effects, especially against infections.

There was another reason for concern, the author comments.

“COVID-19 patients with lower vitamin D levels had raised levels of serum inflammatory markers such as ferritin and D-dimer, that are markers of the hyperinflammatory state that can worse the outcome of the disease.”

What does this mean

As it was often the case with COVID-19, the information about vitamin D has been somewhat contradictory. Several studies have linked vitamin D deficiency with COVID-19 severity, but the National Institutes of Health in the United States found insufficient evidence to recommend for or against using vitamin D supplementation specifically to prevent or treat COVID-19. There’s about a dozen studies at the moment analyzing the effectiveness of vitamin D for preventing or treating COVID-19 but in the meantime, the best available evidence seems only enough to recommend vitamin D to help with COVID-19 prevention for people who are deficient.

Hernández believes the same thing. But most people may not even be aware, he adds.

“The best approach might be to identify and treat vitamin D deficiency, especially in high-risk individuals such as the elderly, patients with comorbidities, and nursing home residents, who are the main target population for the COVID19,” he says.

It’s not just COVID-19 evidence that supports this idea. Vitamin D supplementation in the development of other seasonally prevalent viral respiratory infections also seems to suggest that having adequate levels of vitamin D could protect against the development of COVID-19, Hernández adds. .

“Although we must wait for the results of the ongoing large and well-designed clinical trials to determine whether vitamin D can prevent SARS-COV-2 infection, or reduce its severity, given the large safety margin of vitamin D treatment and its low cost, it seems reasonable treating those populations at high risk for vitamin D, that in general, coincide with the patients most affected by COVID19.​”