Some good news to start off this May: a new study was just published which shows that several supplements, including probiotics, may lessen the risk of contracting COVID-19 in women.[i] (Sorry guys!) A large population study was just published in the British Medical Journal, Prevention and Health, that found that specifically, multivitamins, omega 3s, vitamin D or probiotics. Surprisingly, some supplements that we associate with benefits in the fight against viruses, were not found to be helpful: zinc, vitamin C or garlic.
In order to conduct this study, an app was launched in the UK, the USA and Sweden in March of 2020 to capture a variety of data as the pandemic began shutting down the world. For this study, the scientists used information supplied by over 370,000 UK subscribers during the 3 month period of May, June and July, 2020. About 2/3rds of these app users were women, and (scarily) over half of the users were overweight.
The researchers found that taking probiotics was associated with the greatest reduction in risk for catching COVID – a 14% decrease. Omega 3s led to a 12% reduction, multivitamins a 13% and vitamin D a 8% reduction. Strangely, this reduction of risk was only seen in women, and that, regardless of their weights: “In women, we observed a modest but significant association between use of probiotics, omega-3 fatty acid, multivitamin or vitamin D supplements and lower risk of testing positive for SARS-CoV-2.“ No clear associations were seen in men. There are several potential explanations for this difference between the sexes. Firstly, “… biological explanations include discordant immune systems between sexes that could respond differently to supplements. Indeed, a sexual dimorphism in nutrient metabolism has been previously reported, with females having a more robust immune response than men. Moreover, females typically possess a more resilient immune system than males with higher numbers of circulating B cells when matched for age, BMI and clinical parameters, as well as a slower age-related decline in circulating T cells and B cells.”
This difference between the sexes may also have to do with male versus female behavior. The authors state, “Polling reveals that a greater percentage of females versus males are anxious for the health of themselves or their family and therefore are more precautionary, cancelling plans and staying home more often. Females who purchase vitamins may also be more health conscious than males, such as having greater use of wearing face masks and hand-washing. Indeed, in our data, we found that women tended to wear masks more often than males (44% of women report wearing a mask at least some of the time when outside, compared with 36% of men, p<0.001).”
This same pattern was seen in both the USA users (almost 46,000) and Swedish users (almost 28,000), but interestingly, in the USA probiotics were associated with an 18% reduction in risk, while in Sweden, they led to a whopping 37% reduction in risk.
There are obvious limitations to this study: for, example as the results were self-reported, there was no way to ascertain accuracy, and brands/types/doses of the supplements used is also unknown. Still, the results are significant enough that the researchers are calling for large-scale clinical trials: “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. We eagerly await the result of ongoing trials, including of vitamin D, omega-3 fatty acids and probiotics and COVID-19 risk.”
I am eagerly awaiting those studies too.
[i] Panayiotis Louca, Benjamin Murray, Kerstin Klaser, Mark S Graham, Mohsen Mazidi, Emily R Leeming, Ellen Thompson, Ruth Bowyer, David A Drew, Long H Nguyen, Jordi Merino, Maria Gomez, Olatz Mompeo, Ricardo Costeira, Carole H Sudre, Rachel Gibson, Claire J Steves, Jonathan Wolf, Paul W Franks, Sebastien Ourselin, Andrew T Chan, Sarah E Berry, Ana M Valdes, Philip C Calder, Tim D Spector, Cristina Menni. Modest effects of dietary supplements during the COVID-19 pandemic: insights from 445 850 users of the COVID-19 Symptom Study app). BMJ Nutrition, Prevention & Health, 2021; bmjnph-2021-000250 DOI: 10.1136/bmjnph-2021-000250