In a dish, lion's mane did not thin blood; two other mushrooms did
Hot-water extracts of eight mushrooms were dripped onto human platelets. Jelly ear and king oyster cut clumping; lion's mane did not, and none changed clotting times.
What the study found
Lion's mane was not one of the mushrooms that thinned blood
Hot-water extracts of eight edible mushrooms were dripped onto human platelets. Jelly ear and king oyster suppressed clumping more than aspirin did in one test; lion's mane did not suppress it at all. None of the eight changed any of the three standard clotting-time measures.
The caveat · Earlier work saw a platelet effect
Nobody swallowed anything: these were extracts applied to platelets in a tube, at concentrations matching no serving or capsule. The same paper's introduction cites an earlier report that a lion's mane extract did interfere with one platelet receptor, so even the tube evidence is split.