Nattokinase

A fibrin-dissolving enzyme from fermented soybeans (natto). Modestly lowers blood pressure, dissolves abnormal clots, and — at high doses — has shown carotid-plaque and cholesterol reduction in trials. The catch: the dose does the work, and typical capsules are far too small.

Nattokinase is a serine protease isolated from natto — the traditional Japanese fermented soybean dish. It selectively breaks down fibrin (the protein scaffold of blood clots) and the clot-stabilising plasminogen activator inhibitor. Clinical effects: modest reduction in blood pressure, lowering of fibrinogen levels, and possible dissolution of abnormal microclots. It's been part of the Japanese diet for over 1,000 years (natto consumption tracks with that country's exceptional cardiovascular health) and is now used in functional cardiovascular protocols globally — including in long-COVID microclot protocols. On cholesterol and arterial plaque specifically, the effect is strongly dose-dependent: the largest trial (1,062 people, 12 months; Frontiers in Cardiovascular Medicine, 2022) found ~36.6% average carotid-plaque reduction plus better lipids at 10,800 FU/day, while 3,600 FU/day did nothing — and an earlier head-to-head (Ren 2017) reported it shrank plaque more than simvastatin while raising HDL. Read with honest eyes, though: these standout results come largely from one research orbit, aren't independently replicated, and the strongest designs lacked a true placebo (a separate placebo-controlled trial, NAPS, found no effect on plaque).