Health experts have said more must be done in order to establish whether vitamin D and other selected supplements can help protect people against Covid.
The call from experts comes after a new study found that people taking certain vitamins were less likely to test positive for the virus which causes Covid-19.
The study, which was published in the journal BMJ Nutrition Prevention & Health, analysed data from more than 445,000 people from the UK, United States and Sweden who contribute to the Zoe Covid-19 Symptom Study app.
Information regarding infections and dietary supplements was collated, with researchers finding that among the 372,000 UK participants, women taking probiotics, omega-3 fatty acids, multivitamins or vitamin D had a lower risk of being infected with the virus that causes Covid. The study found that the effects ranged from 9 per cent to 14 per cent lower risk among those who took supplements.
However, no effect was observed for those taking vitamin C, zinc or garlic supplements, and the observation was not seen in men.
Similar findings were also seen in the groups from the US and Sweden.
Although experts at the National Institute for Health and Care Excellence (Nice) have previously said that low levels of vitamin D have been associated with more severe cases of Covid-19, it is difficult to know if low vitamin D levels cause poorer or better outcomes.
Health officials in England have also said that there is “not enough evidence” to recommend taking vitamin D supplements solely for the purpose of preventing coronavirus.
However, health experts from the recent study published in the BMJ Nutrition Prevention & Health journal are calling for large trials in order to assess whether some supplements could have a protective effect against the virus.
The authors, led by academics from King’s College London, wrote: “In conclusion, our data show that women taking multivitamins, omega-3 fatty acids, vitamin D or probiotics have a slightly lower risk of Sars-CoV-2 infection in the UK, US and Swedish cohorts, but no effect in those taking zinc, vitamin C or garlic.
“Given the interest in supplements during the pandemic, large randomised controlled trials of selected supplements testing their protective effects – and also possible adverse effects – on disease severity are required before any evidence-based recommendations can be made.”