This study shows that Vitamin K, D, and A very effectively bind to a certain part of the SARS‐CoV‐2 spike protein (fatty acid binding site) .
Through this mechanism it inhibits viral entry, because it blocks binding to the endogenous ACE2 enzyme.
At least this is how I’m reading it, correct me if I’m wrong.
Interestingly vitamin K2 was the most effective out of all the substances they screened! Vitamin D and K were also up there.
“Vitamin K2 is the highest ranked compound overall; vitamin A acetate is ranked 17th; vitamin D (calcitriol) 24th; vitamin A 38th and vitamin K1 70th.”
"Furthermore, the implication that, by binding to the spike FA site, fat‐soluble vitamins may stabilize the locked form of the spike and inhibit viral entry suggests that these compounds could also play a more direct role in protecting host cells from viral infection. "