Mediterranean diet may provide long-term strategy to reduce COVID-19 risk

Key takeaways:

• Higher Mediterranean diet adherence consistently reduced the risk for COVID-19.
• A nutritional strategy for COVID-19 could be “feasible” over the long term, researchers noted.

Greater compliance with components of the Mediterranean diet significantly reduced the risk for developing of COVID-19, according to the findings of a recent analysis.

However, the diet’s effect on COVID-19 symptoms and severity is still unclear and warrants further investigation, the researchers noted.

Dietary patterns have been previously shown to influence the risk for COVID-19, as one study found that people who followed a plant-based or vegetarian diet had significantly lower odds of contracting COVID-19 vs. those who followed an omnivorous diet.

Ceria Halim, MD, from the University of North Sumatra in Indonesia, and colleagues explained that the Mediterranean diet is rich in antioxidants and has been known to benefit those with disorders tied to low-grade inflammation.

“This has led to the growing proposition of the protective effects of Mediterranean diet towards COVID-19,” they wrote in PLoS One.

In the systematic review, the researchers searched multiple databases and compiled data from six observational studies (n = 55,489) that examined associations between COVID-19 infection, severity or symptoms and adherence to the Mediterranean diet.

The final analysis included studies considered low-to-moderate risk for reporting bias.

Halim and colleagues found that three out of five studies reported that higher adherence to the Mediterranean diet significantly lowered the odds for developing COVID-19, whereas the two other studies showed insignificant results.

All five studies reported ORs ranging from 0.75 to 0.948.

Three studies assessed associations between SARS-CoV-2 infection and individual Mediterranean diet components. Results showed that lower red meat consumption, moderate amounts of alcohol, higher olive oil consumption and a higher intake of fruit and nuts lowered the risk for COVID-19.

Another study found that nuts, fish, legumes, fruits, vegetables and whole grains reduced the risk for COVID-19 severity.

The researchers added that the anti-inflammatory properties of these foods explain their beneficial effects on SARS-CoV-2 infection and severity. For example, “the presence of flavonoids, an antiviral and immunostimulatory compounds, linked fruit consumption to a reduced risk for SARS-CoV-2 infection,” they wrote.

Three of four studies that examined COVID-19 symptoms reported insignificant associations. The study with significant results found that higher Mediterranean diet adherence decreased the odds of symptoms like fever, cough and vomiting, with ORs for each symptom ranging between 0.06 to 0.34.

Halim and colleagues noted that two of the three studies that assessed COVID-19 severity and diet adherence reported inconclusive findings.

Researchers noted several study limitations, including the overall number of studies in the analysis and self-reporting of Mediterranean diet adherence in all the included studies. Meanwhile, they added the magnitude of effects could not be precisely measured because of the lack of a meta-analysis.

Halim and colleagues noted that a nutritional strategy against COVID-19 “may be more feasible and beneficial long term” as countries have loosened regulations on protective equipment and social distancing.

They ultimately concluded that although the results provide insight into the impact diet may have on developing COVID-19, they wrote that “more studies should be conducted before definitive conclusions can be drawn.”