Covid-19 patients with low vitamin D levels are more likely to suffer severe disease and death, according to a study by Irish scientists.
Unvaccinated Caucasian adults with low vitamin D have higher mortality due to Sars CoV-2 pneumonia, according to the small-scale study by researchers at Connolly Hospital Blanchardstown and Technological University Dublin. This is not explained by confounders such as age or obesity and is not closely linked to inflammation, they say.
Having an insufficient level of vitamin D was associated with a greater than fourfold increased mortality risk, according to the study, published in the journal Nutrients.
The study looked at the outcomes of 232 unvaccinated patients at Connolly hospital, all of whom had Covid-19 and required supplemental oxygen. Patients on steroid treatment were not recruited for the study in order, the authors say, to eliminate the effect their use might have on measures of both vitamin D and inflammation.
The mortality rate among patients aged under 70 and who had “insufficient” vitamin D levels (less than 30 nanomoles per litre) was 11.8 per cent, compared to 2.2 per cent who had higher vitamin levels (greater than 30 nanomoles per litre).
Among over-70s, the mortality rate for those with insufficient vitamin D levels was 55 per cent, compared to 25 per cent for those with high vitamin D levels.
“Unvaccinated Caucasian adults with a low vitamin D state have higher mortality due to Sars CoV-2 pneumonia, which is not explained by confounders and is not closely linked with elevated serum CRP (C-reactive protein, an indicator of inflammation),” the authors state.
The authors say their data adds to a growing body of literature that appears to support a causal link between low vitamin D status and Covid-19 disease severity and death.
Although the research was conducted only on unvaccinated patients, they say vitamin D supplementation may play a vital role in protecting both unvaccinated patients and patients in whom the effect of vaccination wanes.
Vitamin D is available from sunlight and in foods such as fish, eggs and fortified cereals. About half the Irish population is deficient in the vitamin.
The Department of Health recommends people aged 65 and over take supplements containing vitamin D for bone health, but a 2021 review found insufficient evidence linking use of the vitamin to the prevention and treatment of Covid-19.