Modest effects of dietary supplements during the COVID-19 pandemic: insights from 445 850 users of the COVID-19 Symptom Study app

Abstract

ObjectivesDietary supplements may ameliorate SARS-CoV-2 infection, although scientific evidence to support such a role is lacking. We investigated whether users of the COVID-19 Symptom Study app who regularly took dietary supplements were less likely to test positive for SARS-CoV-2 infection.DesignApp-based community survey.Setting445 850 subscribers of an app that was launched to enable self-reported information related to SARS-CoV-2 infection for use in the general population in the UK (n=372 720), the USA (n=45 757) and Sweden (n=27 373).Main exposureSelf-reported regular dietary supplement usage (constant use during previous 3 months) in the first waves of the pandemic up to 31 July 2020.Main outcome measuresSARS-CoV-2 infection confirmed by viral RNA reverse transcriptase PCR test or serology test before 31 July 2020.ResultsIn 372 720 UK participants (175 652 supplement users and 197 068 non-users), those taking probiotics, omega-3 fatty acids, multivitamins or vitamin D had a lower risk of SARS-CoV-2 infection by 14% (95% CI (8% to 19%)), 12% (95% CI (8% to 16%)), 13% (95% CI (10% to 16%)) and 9% (95% CI (6% to 12%)), respectively, after adjusting for potential confounders. No effect was observed for those taking vitamin C, zinc or garlic supplements. On stratification by sex, age and body mass index (BMI), the protective associations in individuals taking probiotics, omega-3 fatty acids, multivitamins and vitamin D were observed in females across all ages and BMI groups, but were not seen in men. The same overall pattern of association was observed in both the US and Swedish cohorts.ConclusionIn 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. We found no clear benefits for men nor any effect of vitamin C, garlic or zinc. Randomised controlled trials are required to confirm these observational findings before any therapeutic recommendations can be made.

Consumption of Food Supplements during the Three COVID-19 Waves in Poland—Focus on Zinc and Vitamin D

“…No protective association was observed among men. Moreover, no positive effect was found for respondents taking vitamin C, zinc, or garlic FS [23].…”

Diet quality and risk and severity of COVID-19: a prospective cohort study

“…hPDI, healthful Plant-Based Diet Index. 29 Trace elements, vitamins (A, B 6 , B 12 , C, D, and E, and folate), amino acids, long-chain omega-3 fatty acids (docosahexaenoic and eicosapentaenoic) and nonnutrient-bioactive such as polyphenols have key roles in immune system function and cytokine release, and might partially explain some of the observed associations. Results from this observational study could expand previous single nutrient observations and highlight the beneficial association of healthy dietary patterns, which was most pronounced for risk of severe COVID-19.…”

Patient Nutrition and Probiotic Therapy in COVID-19: What Do We Know in 2021?

“…The human microbiota-miRNA axis may also be used as a therapeutic approach for patients with COVID-19 [32]. Recently, in 2021, it was shown that there is a link between the use of probiotics, omega-3 fatty acids, multivitamin and vitamin D supplements, and reduce the risk of testing positive for SARS-CoV-2 in the case of women (this observation was not confirmed in men) [38]. Probiotics contribute to the restoration of gut microbiota balance and functional homeostasis and prevent the invasion of pathogenic microbes through, among others, increasing the secretion of mucins [35,[38][39][40].…”

“…Recently, in 2021, it was shown that there is a link between the use of probiotics, omega-3 fatty acids, multivitamin and vitamin D supplements, and reduce the risk of testing positive for SARS-CoV-2 in the case of women (this observation was not confirmed in men) [38]. Probiotics contribute to the restoration of gut microbiota balance and functional homeostasis and prevent the invasion of pathogenic microbes through, among others, increasing the secretion of mucins [35,[38][39][40]. Therefore, the aforementioned studies suggest that gut microbiota modification through the administration of probiotic strains appears to be much needed in COVID-19 patients.…”