Natto covid
The Virus and the Spike Protein¶
In 2021, Dr. Tetsuya Mizutani, director of the Center for Infectious Disease Epidemiology and Prevention at the Tokyo University of Agriculture and Technology, published an unexpected finding in Biochemical and Biophysical Research Communications: an extract of natto that had not been heat-treated completely inhibited SARS-CoV-2 from infecting human cells grown in the laboratory.
The mechanism was strikingly direct. The extract contained one or more proteases capable of digesting the receptor-binding domain (RBD) of the virus’s spike protein — the very region it uses to “grab onto” host cells and gain entry. Without a functional spike protein, the virus loses its ability to infect.
The same effect was observed with the Alpha variant and with BHV-1 (bovine herpesvirus), suggesting that the mechanism may extend to other viruses with structurally similar entry proteins.
Mizutani emphasized a crucial nuance — one that any responsible discussion must preserve: these results come from in vitro cell culture experiments. The protease responsible is heat-sensitive and becomes denatured at high temperatures, meaning cooked natto does not retain this activity. And moving from Petri dish results to clinically meaningful effects in humans requires carefully designed trials that have not yet been completed.
What has been firmly established is the mechanism in cellular models — and the researchers have stated their intention to move forward into animal studies.