Editor’s note: It is interesting that this sort of article is published in BMJ. Multivitamins, omega 3 fatty acids, probiotics, vitamin D as supplements are presented in a decent medical journal, meaning that these supplements can be indeed beneficial in preventing covid 19 infection. Also interesting to note is that this article discounts the possible benefits from vitamin C, zinc, or garlic supplements. In any case, this article like many others may not have the final say about how each supplement or vitamin can help prevent or even treat covid 19 infection or any other viral infection. In fact, much evidence suggests all the mentioned supplements when used in a certain dosage can help reduce the risk.
編者註：有趣的是，此類文章在BMJ中發表。 體面醫學雜誌上介紹了多種維生素，歐米伽3脂肪酸，益生菌，維生素D作為補充劑，這意味著這些補充劑確實可以有效預防covid 19感染。 還要注意的是，這篇文章打折了維生素C，鋅或大蒜補充劑可能帶來的好處。 無論如何，這篇文章可能像其他許多文章一樣，對每種補充劑或維生素如何幫助預防或治療covid 19感染或任何其他病毒感染沒有最終決定權。 實際上，有大量證據表明，當以一定劑量使用所有提及的補品可以幫助降低風險。
News Release 19-Apr-2021
But protective effects seen only among women
Taking multivitamins, omega-3, probiotics or vitamin D supplements may lessen the risk of testing positive for SARS-CoV-2, the virus responsible for COVID-19 infection–at least among women–indicates a large population study, published online in the journal BMJ Nutrition Prevention & Health.
But taking any of vitamin C, zinc, or garlic supplements wasn’t associated with a lower risk of testing positive for the virus, the findings show.
There has been plenty of celebrity endorsement of the use of dietary supplements to both ward off and treat COVID-19 infection since the start of the pandemic, note the researchers.
In the UK alone, market share rose by 19.5% in the period leading up to the first national ‘lockdown’ on March 23 last year, with sales of vitamin C rising by 110% and those of multivits by 93%.
Similarly, zinc supplement sales rose by 415% in the first week of March, at the height of COVID-19 fears in the USA.
Dietary supplements can help to support a healthy immune system, but whether specific supplements might be associated with a lower risk of catching SARS-CoV-2 isn’t known.
In a bid to plug this knowledge gap, the researchers drew on adult users of the COVID-19 Symptom Study app to see if regular supplement users were less likely to test positive for SARS-CoV-2.
The app was launched in the UK, the US, and Sweden in March 2020 to capture self-reported information on the evolution of the pandemic.
Initially, it recorded the location, age and core health risk factors of its users. But as time went on, subscribers were asked to provide daily updates on a range of issues, including symptoms, coronavirus test results, and healthcare. People without obvious symptoms were also encouraged to use it.
For the purposes of this study, the researchers analyzed information supplied by 372,720 UK subscribers to the app about their regular use of dietary supplements throughout May, June, and July 2020 during the first wave of the pandemic as well as any coronavirus swab test results.
Between May and July,175,652 UK subscribers regularly took dietary supplements;197,068 didn’t. Around two thirds (67%) were women and over half were overweight (BMI of 27).
In all, 23,521 people tested positive for SARS-CoV-2 and 349,199 tested negative between May and July.
Taking probiotics, omega-3 fatty acids, multivits or vitamin D was associated with a lower risk of SARS-CoV-2 infection: by 14%, 12%, 13% and 9%, respectively, after accounting for potentially influential factors, including underlying conditions and usual diet.
No such effects were observed among those taking vitamin C, zinc, or garlic supplements.
And when the researchers looked specifically at sex, age and weight (BMI), the protective associations for probiotics, omega-3 fatty acids, multivits and vitamin D were observed only in women of all ages and weights. No such clear associations were seen in men.
Despite some differences, the same overall patterns were mirrored in both the US (45,757) and Swedish (27,373) subscribers.
The equivalent figures for the US and Sweden were a reduced risk of:18% and 37%, respectively for probiotics; 21% and 16%, respectively, for omega-3 fatty acids; 12% and 22%, respectively for multivits; and 24% and 19%, respectively, for vitamin D supplements.
This is an observational study, and as such, can’t establish cause. The researchers also acknowledge several limitations, including that the study relied on self reported data and a self selected group. No information was collected on supplement doses or ingredients either.
But although the observed effects were modest, they were significant, note the researchers, who call for large clinical trials to inform evidence-based therapeutic recommendations.
“We know that a range of micronutrients, including vitamin D, are essential for a healthy functioning immune system. This, in turn, is key to prevention of, and recovery from, infections.
“But to date, there is little convincing evidence that taking nutritional supplements has any therapeutic value beyond maintaining the body’s normal immune response,” comments Professor Sumantra Ray, Executive Director, NNEdPro Global Centre for Nutrition and Health, which co-owns the journal.
“What’s more, this study wasn’t primarily designed to answer questions about the role of nutritional supplements in COVID-19. This is still an emerging area of research that warrants further rigorous study before firm conclusions can be drawn about whether specific nutritional supplements might lessen the risk of COVID-19 infection,” he cautions.
Externally peer reviewed? Yes
Evidence type: Observational