Probiotics, omega-3 fatty acids, multivitamin or vitamin D supplements are associated with a reduced risk of coronavirus infection in women, but not in men, while vitamin C, garlic and zinc do not show a clear benefit in both, according to the latest findings from users of the COVID-19 Symptom Study app.
The study is the largest observational study on the use of SARS-CoV-2 infection and dietary supplements to date, based on data from more than 400,000 app users from the UK, US and Sweden. Similar results were found in all three countries and are published in the journal today BMJ Nutrition Prevention and Health.
Cristina Menni, PhD, specializes in gut microbiome and metabolomics at the Department of Twin Research and Genetic Epidemiology, King’s College London, and led the study. “We had a very large sample size looking at the correlation between the supplements and COVID-19, and found that vitamin D, probiotics, multivitamins and omega-3 showed a modest reduction in the chances of catching COVID-19,” she said. Medscape News UK in an interview.
“We can’t make a recommendation based on this alone, but it does lay the groundwork for a larger randomized controlled trial.”
Dr. Menni adjusted the results for the diet, which of course may affect the outcome. However, “it appears that the effect of multivitamins, vitamin D, omega-3 is completely independent of the diet. The association with probiotics persists after adaptation, but the effect is smaller,” she explained.
The risk reduction was maintained in women of all ages and body mass index (BMI) groups for probiotics, omega-3 fatty acids, multivitamins and vitamin D. For probiotics, the odds ratio (OR) ranged from 0.73 (95% CI: 0). , 63 to 0.85) in women under 40 years of age; up to OR 0.91 (95% CI 0.86 to 0.96) for vitamin D in women 40-60 years of age.
“We found that women enjoy better protection,” reported Dr. Menni. “But women are usually the ones who buy family supplements, and usually the ones who use them.”
Increase in sales of multivitamins, vitamin C and zinc since pandemic
Sales records show a sharp increase in the intake of vitamin supplements, with the UK market share of vitamin C increasing by 110% and that of multivitamins by 93% in the period leading up to the first lockdown (March 2020).
In the US, zinc supplement sales were up 415% in the first week of March, at the height of COVID-19 fears there. Given the increase in supplement use, the researchers wanted to know if these high sales were justified by their effect on testing positive for SARS-CoV-2 infection.
“However, based on these results, we do not recommend that people run to the pharmacy,” said Dr. Menni.
The finding about vitamin C, which shows no effect on infection rates, may be related to behavioral patterns of consumption, Dr. Menni added. “People may start taking vitamin C when they are already sick rather than routinely every day. The pattern of taking vitamin C is different from that of taking vitamin D or multivitamins.”
Behavioral factors, especially health-related factors, can also influence the findings. “It is true that we found that vitamin D, multivitamins, probiotics and omega-3 reduce the risk of COVID-19, but there may be a bias in the healthy user because the people who report on the app are more health conscious.”
Data provided by the COVID-19 Symptom Study App
Data is from the COVID-19 Symptom Study app which collects self-reported information related to SARS-CoV-2 infection, including location, age, major health risk factors, daily updates on symptoms, medical visits, SARS-CoV-2 test results , quarantine yourself and all the care sought. Asymptomatic people also used the app. A total of 372,720 users in the UK, 45,757 from the US and 27,373 from Sweden contributed their data to the app.
The information analyzed in this study related to app users aged 16-90 years, who used dietary supplements regularly (> three times a week for at least 3 months) in May, June and July 2020 (the first wave of the pandemic), as well as data on any coronavirus smear test results (confirmed by PCR test). Users were asked to complete their own questionnaire asking about their use of probiotics, garlic, omega-3 fatty acids, multivitamins, vitamin D, vitamin C and zinc, or whether they were taking supplements. The control group consisted of users who did not take any supplements.
Data were adjusted for age, gender, BMI and health status at enrollment, co-morbidity (including type 2 diabetes, cancer, asthma, heart disease, eczema, hay fever, kidney disease, and lung disease), multiple deprivation index (IMD), smoking, ethnicity, health worker / caregiver and nutritional quality.
Generally modest protective effect
Dr. Menni and colleagues found that during the first wave, 175,652 subscribers in the UK were regularly taking nutritional supplements, and 197,068 were not. In total, 67% of people taking supplements were women and more than half were overweight (mean BMI of 27). A total of 23,521 people tested positive for SARS-CoV-2 and 349,199 negative over the 3 months.
Specifically in UK 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%)), after adjusting for possible confounding factors.
The risk reduction for testing positive for SARS-CoV-2 using omega-3 fatty acids was 21% in the US cohort and 16% in the Swedish cohort. Probiotics were modestly protected against infection with a risk reduction of 18% in the US cohort and 37% in the Swedish data.
With multivitamins, the risk of SARS-CoV-2 was reduced by 12% in the US cohort and 22% in the Swedish cohort. With vitamin D the risk reduction was 24% and 19%, respectively.
Probiotics improve the gut microbiome and boost immunity
Commenting on the modest effect of probiotics on risk reduction, Dr. Menni said that a healthy diet could have had a disruptive effect on the association found.
“A recent study linked the gut microbiome to the immune response in COVID-19 and we also know that the severity of COVID-19 is related to the gut microbiome.”
As for probiotics, these improve microbiome diversity, which is good for the immune system and, as such, is less likely to cause a person to get sick, she added.
“The finding on probiotics opens many potential opportunities for research and supports a clinical trial with probiotics.”
Professor Sumantra Ray, Executive Director, NNEdPro Global Center for Nutrition and Health, co-owner of the journal, commented on the findings. “To date, there is little conclusive evidence that taking nutritional supplements has therapeutic value beyond maintaining the body’s normal immune response.
“In addition, this study was not primarily intended to answer questions about the role of dietary supplements in COVID-19.”
The researchers recognize that it is an emerging area of research and requires further rigorous research, including RCTs, examining potential protective effects on infection and disease severity, as well as side effects, before definitive conclusions can be made about the role of dietary supplements in preventing infection. with SARS-CoV2. They also note that the study was based on self-reported data and a self-selected group. No information was also collected on supplement doses or ingredients.
COI: Dr. Menni declares no conflicts of interest. Other authors list a range of interests on the paper.
Published in the April 19 edition of the journal BMJ Nutrition Prevention and Health