8-1- Fermented vegetables and Kimchi
It is tempting to propose that countries where traditional LAB-fermented
vegetables are largely consumed are those showing lower COVID-19 death
rates and that fermented vegetables represent one possible preventive
approach. Other nutrients are found in these products that may enhance
their effect (e.g. vitamin K 122). Kimchi fermented
from many vegetables including cabbage has several effects on insulin
resistance associated diseases: anti-diabetic properties,123,124 cardiovascular diseases, 25dyslipidemia 125 or ageing. 126Kimchi, when fermented for a long time, reduces insulin intolerance to a
greater extent than fresh kimchi, 123 indicating that
newly formed products during fermentation are important. In particular,
Kimchi from cabbage and Chinese cabbage contains several glucosinolates127-129 that can be transformed in sulforaphanes
either in the plant itself or by the human microbiome.57 In central European countries, raw and fermented
cabbage is commonly consumed.
In Sub-Saharan Africa, people commonly eat fermented foods, mainly
cereal-based foods like sorghum, millet and maize, roots such as
cassava, fruits and vegetables.
It is clear that sauerkraut is consumed in Alsace (France) where a
COVID-19 outbreak has been identified, but it is not a regular meal.
Westernized diets contain a reduced amount of fermented vegetables40,130 and may be prone to increasing insulin
resistance 41,131 and diseases associated with it,132 and thereby severe COVID-19.
In the Mediterranean diet, well known for reducing insulin resistance,133 Nrf2 appears to play an important role.68,134 The COVID-19 death rate differences in Italian
(Figure 2) and Spanish 2 regions suggest a role for
Mediterranean diet and short chain food supply. This also indicates that
many foods can have an effect and that cabbage and fermented foods
represent a proof-of-concept. Nrf2 is also involved in the
Okinawan-based diet 68, active on insulin intolerance.135 Taken altogether, it is possible that diet is
partly involved in the COVID-19 death clusters found in large Western
cities where traditional diet is often replaced by long chain food
supply.