Taking supplements could give women a lower risk of Covid-19 – but the same result was not seen in men, according to a new study.
The study examined 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 on infections as well as dietary supplements were collated.
Among the 372,000 UK participants, researchers found that women taking probiotics, omega-3 fatty acids, multivitamins or vitamin D had a lower risk of being infected with the virus that causes Covid-19 – with the effects ranging from 9% to 14% lower risk among those who took supplements.
No effect was observed for those taking vitamin C, zinc or garlic supplements. The observation was not seen in men. Similar findings were also seen in the groups from the US and Sweden.
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.”
The researchers of the study, published in the journal BMJ Nutrition Prevention & Health, emphasised that more must be done to establish whether vitamin D supplements can help protect against Covid-19.
Health officials in England have said that there is “not enough evidence” to recommend vitamin D supplements solely for preventing Covid‑19.
Experts at the National Institute for Health and Care Excellence (Nice) have said previously low levels of vitamin D have been associated with more severe Covid-19 – but it is difficult to know if low vitamin D levels cause poorer outcomes or vice versa.
There is already guidance that recommends that anyone over the age of four should consider taking a daily supplement containing 10 micrograms of vitamin D between October and early March to maintain bone and muscle health. People in the UK do not make enough vitamin D from sunlight in these months.