Is there enough evidence to support the role of vitamin D for Covid-19? We asked an expert

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  • The potential role of vitamin D protecting against Covid-19 has once again been thrust into the spotlight after a recent study was published
  • However, the study, which was not peer-reviewed, has since been retracted
  • Health24 spoke to a professor in nutrition science who said that further research is needed, and warned against taking high doses as a preventative

The Covid-19 pandemic has brought on a heightened fear of infection for us and our loved ones, leading us to do all we can to minimise exposure and improve our overall immunity.

But while maintaining a healthy vitamin D level can play a role in having a healthy immune system, it’s unclear whether it may help us to fight Covid-19 more effectively and quickly, as well as reduce the chances of hospitalisation – as some studies have suggested.

Health24 spoke to Marjanne Senekal, Professor in Nutrition Science in the Department of Human Biology at the University of Cape Town. Senekal cautioned against broad conclusions, saying that there is not enough basis for suggestions that vitamin D can act as a treatment for the disease, and that further studies are needed.

Recently published study now withdrawn

Last week, Health24 reported on a preprint study, published in January, which suggested that calcifediol – another name for vitamin D3 – significantly reduced hospital admissions and mortality in Covid-19 patients.

The researchers from the University of Barcelona also stated the Covid-19 patients in the intensive care unit (ICU) they studied, had improved outcomes after taking vitamin D as part of their medication regime.

However, the study’s abstract has since been retracted pending investigation of the "description of the research" in the paper.

Multiple factors at play

In June last year, Senekal told Spotlight that having sufficient levels of vitamin D is extremely important, but is a completely different issue to potentially using it as a short-term treatment for Covid.

Vitamin D is not a “magic bullet” in the prevention or treatment of disease, including Covid-19, she said, and added that although vitamin D sufficiency is important, it is only one factor in what she labelled a “complex soup” of genetic and dietary factors, and physical activity, nutritional status, age and overall health that determine a person’s susceptibility to disease.

Senekal told Health24 that her view on vitamin D for Covid-19 is still very much the same: “My professional view remains that the population should be educated regarding the importance of having sufficient vitamin D levels and how to achieve that without excessive sun exposure and taking high dosage vitamin D supplements, which can both be dangerous,” she said.

More detailed results are needed

Senekal referenced a quote from a paper in Metabolism Clinical and Experimental in August 2020. In this paper, the authors broke down the myths and facts on vitamin D amidst the Covid-19 pandemic, and wrote:

“The role of vitamin D supplementation in Covid-19 patients, to enhance disease resistance or as adjuvant therapy, awaits results of well-designed experimental studies,” – a point that Senekal supports.

“Evidence for the role of vitamin D as a Covid-19 treatment remains inconclusive exactly because the studies that have been done have not been well-designed (illustrated again now by the retraction of the abstract pending investigation of the research methods and integrity),” said Senekal. She added:

“One point that seems to be common across these preliminary studies, including the retracted one, is that hospitalised Covid-19 patients with low levels of vitamin D seem to be more likely to respond to the supplement.

"But this may be the result of addressing the vitamin D deficiency and that once the deficiency is addressed, further doses of vitamin D – above basic requirements – may not have a further effect, as is illustrated by the fact that those with higher vitamin D levels when the supplementation starts in hospital, seem to be less likely to respond.”

These findings raise an important point, said Senekal: that public health initiatives should focus on ensuring that the population is vitamin D sufficient, especially during this time.

Senekal cautioned against taking high doses of vitamin D and believing that this may have extra protective effects against Covid-19. In fact, longer-term intakes of 100mcg (4000 IU) or more per day may result in negative health outcomes, she said. 

READ | How Covid vaccines get approved: 4 things you need to know

READ | UK set to begin world’s first Covid-19 human challenge trial – but is it still necessary?

READ | Scientists to discuss Pfizer/BioNTech vaccine lab study which found decreased protection vs variant

Image credit: Getty Images

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