A Higher Omega-3 Index Protects Against Severe COVID-19 Infection

Can your nutritional status reduce the risk of contracting COVID-19? Can it reduce the risk of severe or fatal disease progression?

An original research article, published in The American Journal of Clinical Nutrition, sought to answer these questions. The investigators examined the role of the omega-3 fatty acids EPA and DHA to determine whether they were protective against contracting and/or suffering adverse outcomes of COVID-19.

Demographic and physiological characteristics, such as age, comorbidities, and obesity, are known to affect COVID-19 illness severity. However, nutrients like zinc, dietary bioactive, and vitamins C and D have been implicated as potentially protecting against symptomatic and severe COVID-19.

Preliminary studies have suggested that a higher intake of n-3 polyunsaturated fatty acids (PUFA) is protective against COVID-19 infection. Specifically, EPA and DHA, long-chain n-3 PUFAs of marine origin, may protect against COVID-19.

EPA and DHA are inflammation-resolving mediators, downregulating the production of cytokines, improving macrophage-mediated removal of debris and microbes, and promoting apoptosis of neutrophils.

The investigators evaluated the risk of 3 COVID-19 illness outcomes as a function of baseline plasma DHA levels: 1) testing positive, 2) hospitalization, and 3) death.

The final study cohort included 110584 participants, recruited between 2007-2010 as part of the UK Biobank (UKBB) cohort across England, Scotland, and Wales.

The investigators measured participants’ DHA levels, or the percentage of total fatty acids, using Nuclear Magnetic Resonance spectroscopy. Then, the data were converted to Omega-3 Index, or red blood cell EPA+DHA%, for the final analysis.

In fully adjusted models, participants with the highest Omega-3 Index levels (classified as quintile 5) were 21% less likely to contract COVID-19 than the participants with the lowest Omega-3 Index levels (quintile 1). The risk of a positive COVID-19 test was 8% lower for each 1-standard deviation increase in plasma DHA percentage.

Additionally, quintile 5 patients (those with the highest omega-3 PUFAs) were 26% less likely to be hospitalized for COVID-19 than quintile 1 patients. This risk of hospitalization was 11% lower per 1-standard deviation increase in DHA percentage.

The risk of COVID-19 death was slightly lower through quintile 4, but in quintile 5 patients, the risk reduction became nonsignificant. Notably, Omega-3 Index levels ranged for 3.5% in quintile 1 to 8% in quintile 5.

These results merit further investigation, particularly into the lack of a significant COVID-19 death reduction in the participants with the highest levels of omega 3 polyunsaturated fatty acids.

The investigators note that the populations of South Korea and Japan have exhibited extremely low COVID-19 illness severity. Healthy individuals in South Korea have Omega-3 Index values of 8-12%, while these levels are 7-11% in health Japanese individuals. In Western nations like the United States, Omega-3 Index values average 4-5%. In addition to a culture of attentiveness to disease prevention practices, high omega-3 levels may have helped reduce the risk of COVID-19 disease severity in South Korea and Japan.

“These findings suggest that nutritional strategies to increase the circulating n-3 PUFA levels, such as increased consumption of oily fish and/or use of n-3 FA supplements, may reduce the risk of adverse COVID-19 outcomes,” the study authors concluded.