“This study confirms previous findings that low omega-3 (n-3) status is associated with increased risk for hospitalization with COVID-19,” said FARI President William Harris, PhD, FASN. “We extended these findings by also showing reduced risk for testing positive with the infection and by providing evidence that the risk for death may also be reduced.”
The study, published in the American Journal of Clinical Nutrition, used a subset of data from the UK Biobank, a prospective cohort study of approximately 500,000 individuals recruited between 2007 and 2010 across England, Wales and Scotland.
Omega-3s and COVID-19
The FARI research builds on two prior studies that linked higher Docosahexaenoic acid (DHA) omega-3 levels, among several other biomarkers, with a lower risk of infection or hospitalization with COVID-19 in the UK Biobank cohort.
A number of smaller studies have also shown that higher red blood cell levels of omega-3s at admission were associated with a lower risk of adverse COVID-19 outcomes, and pilot intervention studies have reported possible benefits from omega-3 supplementation in COVID-19 patients.
“The present study aimed to expand upon the work of these investigators by examining the n-3 relations with additional COVID-19 outcomes (i.e., death), performing more granular analyses (i.e., quintiles), exploring the effects of several covariates on these relationships and translating n-3 biostatus into the Omega-3 Index (O3I), a more commonly used measure of n-3 status,” the researchers wrote.
Because omega-3s contribute to downregulating the production of cytokines, improving macrophage-mediated removal of inflammatory debris and microbes and promoting apoptosis of neutrophils, the study suggested that higher levels of EPA and DHA omega-3s in the tissues could reduce the severity of the inflammatory response to SARS-CoV-2 infection.
Between January 2020 and March 2021, the researchers compared the risk of testing positive, hospitalization and death from COVID-19 to baseline plasma DHA levels.
These three outcomes, along with relevant covariates, were available for 110,584 subjects (hospitalization and death) and for 26,595 subjects (with a positive COVID-19 PCR test result). Participants were primarily white men and women with a mean age of 68 years. Estimated Omega-3 Index values across the five DHA groupings ranged from 3.5% (quintile 1) to 8% (quintile 5).
The study found that a 1-SD [standard deviation] higher DHA% was associated with an 8% lower risk of testing positive for SARS-CoV-2 and an 11% lower risk of hospitalization in the multivariable adjusted models. Results also linked higher DHA status with reduced risk of mortality from COVID-19 across the first four DHA quintiles in a strongly dose-related manner, although it was unclear why this trend reversed in the highest quintile.
“We identified the Omega-3 Index levels associated with the least (<4%) and greatest (>8%) protection from COVID-19,” Dr. Harris said. “Altogether these results support the practice of increasing consumption of oily fish like salmon or omega-3 fish oil supplements as a potential risk reduction strategy when it comes to COVID-19.”
In an editorial accompanying the study, Dr. Philip Calder, professor of nutritional immunology within medicine at the University of Southampton, UK agreed that increased long-chain omega-3 intake should be encouraged as a strategy to combat COVID-19 and future respiratory virus infection outbreaks.
“It is possible that those with higher DHA status, which would most likely result from eating fatty fish or using omega-3 supplements, show greater compliance with health behaviors that limit exposure to SARS-CoV-2 and therefore are less likely to test positive,” he added. “However, it is also possible that DHA has effects that restrict viral entry to host cells, limit viral replication or promote virus elimination so that post-SARS-CoV-2 exposure, evidence of infection is absent.”
Source: The American Journal of Clinical Nutrition
“Association between blood N-3 fatty acid levels and the risk of coronavirus disease 2019 in the UK Biobank”
Authors: William Harris et al.