Heterogeneity of COVID-19 death rates in countries and relation
to diet
When comparing death rates, large differences exist between and within
countries (Figure 1). Although many factors are involved in COVID-19
mortality,5-11 a recent hypothesis has proposed that
differences between countries may partly be explained by diet: the diet
of low-death rate countries often includes certain vegetables that are
potent anti-oxidants.12 Two studies have examined the
association between the COVID-19 mortality rate in EU countries and
diet. Fermented vegetables, head cabbage and cucumber have been
associated with lower death rates.13,14 Even though
these are ecological studies, they support the association between diet
and fatality. A healthy diet, rich in antioxidants, has been proposed as
a therapeutic strategy to mitigate the cytokine storm that developed in
COVID-19.15 In Asia and the Middle East, a diet high
in fermented cruciferous vegetables is common, and these countries have
a lower COVID-19 mortality rate. Fermentation food processing is known
to increase the antioxidant activity of foods.16Certain compounds found in the diet can interact with Nrf2 (nuclear
factor erythroid 2 p45-related factor 2), a transcription factor
involved in the protection against oxidative stress.17