While in some countries the vaccine rollout is well advanced, many of us still live amid the risks of the COVID-19 pandemic without protection and need all the help we can get.
An interesting study by an international team of researchers has now found a small association with supplement use, indicating fewer COVID-19 infections in women who take certain types of vitamins. But don’t rush to the pharmacy just yet.
First, it’s important to remember that the potential merits of multivitamins are extremely limited. Doctors generally advise most people to get enough micronutrients in their diet to stay healthy, and in the past, studies of the health benefits of vitamin supplements without a diagnosed deficiency have been very mixed.
Despite this, at the start of the pandemic, vitamins were one of the many items flying off drugstore shelves.
“The UK supplement market grew 19.5% in the run-up to the nationwide ‘lockdown’ in early March 2020, with sales of vitamin C increasing 110% and sales of multivitamin supplements by 93% “the team wrote. .
Likewise, sales of zinc supplements increased 415% in the 7-day period ending March 8, at the height of concern over COVID-19 in the United States.
Supplements can have a role to play in supporting our health. Zinc is one of the few micronutrients linked to shortening the course of cold disease; people on a vegan diet are recommended to take vitamins B12 to help fight against deficiencies. But avoiding infections is where it gets difficult.
Researchers extracted data from an app launched by health sciences company Zoe in early 2020 called the “COVID-19 Symptom Study App,” which asked participants a wide range of questions, including they used vitamins such as probiotics, garlic, fish oils, multivitamins, vitamin D, vitamin C or zinc. They also asked if they had been tested for SARS-CoV-2 and what the results were.
A total of 445,850 subscribers from the UK, US and Sweden responded to the questionnaire by July 31, 2020, giving the team plenty of data to analyze.
In the UK, where the vast majority of respondents were based, just under half took some kind of supplement. About 6 percent of those who took the supplements tested positive for SARS-CoV-2, while 6.6 percent of those who did not take the supplements tested positive. That’s a difference of about 2,500 people.
“In the UK cohort, users who regularly supplemented their diet with multivitamins had a 13% lower risk of testing positive for SARS-CoV-2, vitamin D had a 9% lower risk, probiotics had a lower risk of testing positive for SARS-CoV-2. 14% lower risk and with omega-3 fatty acids the risk was 12% lower, ”the researchers wrote.
“There were no significant associations in those who took zinc, vitamin C or garlic supplements.”
There are a lot of caveats here to be aware of. First, this is an observational study based on self-reports, which means there is no causal evidence that vitamins have resulted in fewer diagnoses of COVID-19.
The team adjusted for age, gender, BMI, and a number of other factors, and tried to account for the “healthy user bias,” which is the idea that those who take vitamins are also likely to be healthier in other ways, which could confuse the results.
Even after all this, the results were still there, but it’s interesting that once the team split the results by gender, for men there was no difference related to supplements, while in women, results were present for all ages and BMI groups.
The results were also slightly different between the US and Sweden, finding that omega-3 supplements didn’t seem to help Swedish women, and probiotics and vitamin D seemed to help American men.
“In the largest observational study on SARS-CoV-2 infection and dietary supplement use to date on over 400,000 app users from three different countries, we show a significant association between users of omega-3 fatty acid supplements, probiotics, multivitamins or vitamin D and a lower risk of testing positive for SARS-CoV-2 infection, ”the team wrote.
“Women who buy vitamins may also be more health conscious than men, for example by wearing more face masks and washing their hands. Indeed, in our data, we found that women tended to wear masks more often than men.
After all this, the results show a very modest difference; for example, taking vitamins only reduced the absolute risk of contracting COVID-19 by less than 1% among study participants in the UK.
But at the population level, even tiny percentage points can save lives, so it’s imperative to determine whether it’s really the vitamins that make the difference.
The researchers requested a large clinical trial to test the potential effects in a more controlled setting. For now, if you haven’t gotten a vaccine yet, masks, good hygiene, and social distancing are still likely to keep you much safer than any vitamin.
“This study was not primarily designed to answer questions about the role of nutritional supplements in COVID-19,” says Sumantra Ray, a nutritionist from Cambridge who was not involved in the study.
“This is still an emerging area of research that deserves more rigorous study before firm conclusions can be drawn as to whether specific nutritional supplements could reduce the risk of COVID-19 infection. “
The research was published in BMJ Nutrition Prevention & Health.