evidence: Nattokinase is an enzyme that was first isolated from natto, a traditional Japanese dish made of fermented soybeans. Research so far has shown that it can break apart proteins involved in blood clotting, which enables it to dissolve blood clots. While one study by Tanikawa et al. found that nattokinase could break down spike protein, the study was unrelated to long COVID and the experiments were performed in cells in the lab. Therefore, the results may not reflect what happens in the human body and also provide no information about its effects on long COVID.