1) High consumption of salty foods that contain free chondroitin sulfate, especially the national dish feijoada, a black bean stew that is typically made by boiling several cuts of meat--including cartilige-filled pig ears--for several hours. Chondroitin sulfate is an important structural component of cartilage. There is a case study of a man in Japan who induced the same respiratory tract symptoms as seen in Covid-19 cases merely by taking supplemental sodium chondroitin sulfate:
"A case of drug-induced pneumonia caused by sodium chondroitin sulfate"
T. Itoh, Y. Hamanaka,
Japanese Journal of Chest Diseases 71(6):593-598, June 2012
Abstract: A 49-year-old man was admitted to the hospital with complaints of fever and dry cough. Chest X-ray film revealed ground-glass attenuation in both lung fields, so he was transferred to our hospital for further examination. Chest CT film showed ground-glass attenuation in both lung fields. A transbronchial lung biopsy revealed infiltration of lymphocytes and neutrophils, thickening of alveolar walls and proliferation of type II pneumocytes. By careful history taking, he admitted he had taken sodium chondroitin sulfate for one month before admission. The lymphocyte-stimulation test was positive for sodium chondroitin sulfate. Based on the above findings, we diagnosed this case as drug-induced pneumonia caused by sodium chondroitin sulfate. He recovered after discontinuation of the drug without corticosteroid therapy.
https://www.researchgate.net/publication/287575000_A_case_of_drug-induced_pneumonia_caused_by_sodium_chondroitin_sulfate
A salty feijoada stew is full of both sodium and readily available chondroitin sulfate, which I suspect combine to form some sodium chondroitin sulfate. And it's not just feijoada. The Brazilian go-to food for treating colds is canja de galinha, which similarly involves boiling down cartilaginous chicken portions for a long time in salty water. (https://en.wikipedia.org/wiki/Canja_de_galinha)
(If my hypothesis about this connection is correct, then it could also be a small factor helping to explain the higher Covid-19 burden seen in Ecuador and Peru, where "seco" stews are popular, cooked for many hours, and frequently made with cuts of meat that include bones and connective tissue. But I suspect high starch consumption and resulting metabolic syndrome-related consequences are probably much more to blame in Ecuador and Peru.)
2) High coffee consumption. Coffee drinking raises levels of the cytokine interleukin-6, levels of which correlate with Covid-19 symptom severity, in otherwise healthy people.
3) Relatively low consumption of foods/spices that reduce the level and effects of the cytokine interleukin-6, particularly ginger, hibiscus, and fermented shrimp paste (glucosamine, which is found in shrimp shells, can prevent binding of interleukin-6 to cells).
