To the Editor,
A COVID-19 epidemic started in China and then disseminated to other Asian countries before becoming a pandemic. It appears that the pandemic has so far resulted in proportionately fewer deaths in China and most Eastern Asian countries. Many reasons can explain this picture.1 One of them is the type of diet in the low mortality countries. 2
This paper is the sixth of a series attempting to understand the role of diet in the differences of COVID-19 death rates between and within countries with the aim to identify potential preventive measures against COVID-19. The concept paper 2 was followed by two ecological studies comparing death rates in European countries and the consumption of vegetables or fermented foods. 3,4 We then proposed that sulforaphane from cruciferous vegetables1 and lactobacilli from fermented foods (submitted) were possibly involved in the reduction of insulin resistance in COVID-19.
It is noteworthy that fermented foods are largely used in Asia.5,6 It is therefore important to check whether some commonly eaten fermented foods in these countries may explain geographic differences in COVID-19. Kimchi will be used as a model of fermented cabbage.