Eating Mediterranean diet may offer some protection against COVID-19, unravels study

The growing interest in the Mediterranean diet has noted its anti-inflammatory and immunomodulatory properties, directed towards immune responses. Due to the potential importance of immune modulation in COVID-19 immunopathogenesis, the Mediterranean diet has been proposed to influence COVID-19 risks and severity. The objective of this systematic review was to synthesize all available evidence concerning the relationship between adherence to the Mediterranean Diet and COVID-19 outcomes in terms of the risk of infection, the manifestation of symptoms, and the severity of disease.

The protocol of the current systematic review had been registered in the International Prospective Register of Systematic Reviews (PROSPERO), under the identification number CRD42023451794. A literature search in PubMed, ProQuest, and Google Scholar was conducted in August 2023. Six observational studies comprising a total of 55,489 patients, was conducted to evaluate the relationship between Mediterranean Diet consumption and COVID-19 outcomes.Studies included in this review were those on human populations assessing the relationship of adherence to the Mediterranean Diet with the risk of COVID-19 infection, symptom severity, or disease outcomes. On the contrary, studies excluded were those that had full text in other languages apart from English. Reviews, editorials, letters, animal studies, and duplicates were also removed from the search results.

The risk of bias was evaluated using Newcastle-Ottawa Scale. The review presented a narrative synthesis, making comparisons across studies to provide a structured summary.

Key Findings

• Of the articles reviewed, six studies met the inclusion criteria, covering a combined sample of 55,489 patients. All the studies were observational and used food frequency questionnaires for assessing adherence to the Mediterranean Diet. Adherence scoring systems differed across studies.

• Of the six studies, four showed a statistically significant association of higher adherence to the Mediterranean Diet with a lower COVID-19 infection risk. The measure of association, across studies, for reduced COVID-19 risk in high-adherence groups ranged from an (OR:0.06-0.992). However, one study showed that the association was not significant.

• One of the studies found a significant association between better adherence to the Mediterranean Diet and lower COVID-19 severity; three other studies did not show a significant association.

• Among the studies done assessing COVID-19 severity, one of the researches indicated that higher adherence to the Mediterranean Diet was associated with low chances of severe illness development; another two studies were inconclusive, and non-significant results indicated the effect of the diet in the severity of COVID-19.

The majority of the studies included in this review Used self-administered food frequency questionnaires to measure adherence to the MD. These are then liable to bias in recall and estimation of dietary intake. Moreover, there is always potential inconsistency related to heterogeneity in scoring tools and dietary patterns across studies.

In summary, a high degree of adherence to the Mediterranean Diet seems to act as a protective factor against COVID-19 infection. Its benefits with respect to COVID-19 symptoms and the severity of disease are less certain. The review reinforces that dietary habits play an important role in disease prevention and that the use of the Mediterranean Diet could be an important addition to reducing the burden of COVID-19.

Reference:

Halim, C., Howen, M., Fitrisubroto, A. A. N. B., Pratama, T., Harahap, I. R., Ganesh, L. J., & Siahaan, A. M. P. (2024). Relevance of Mediterranean diet as a nutritional strategy in diminishing COVID-19 risk: A systematic review. PloS One, 19(8), e0301564. https://doi.org/10.1371/journal.pone.0301564