Nattokinase is an enzyme from natto, a fermented soybean food, that breaks down fibrin, a protein in blood clots. It is taken as a supplement for heart and blood vessel health, on the idea that it may prevent clots and lower blood pressure.
Also known as: NSK-SD, natto enzyme.
Nattokinase is labeled by activity in fibrinolytic units (FU) rather than by weight. The 3-year trial used 2,000 FU (Hodis 2021). These are study protocols, not a recommendation.
It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling.
What studies show: in a placebo-controlled trial of 265 people (median age 65) without heart disease, about 3 years of nattokinase (2,000 FU) did not slow thickening or stiffening of the neck arteries and had no effect on blood pressure or on any lab test, including clotting and clot-breakdown factors (Hodis 2021). A 2023 meta-analysis of 6 trials (546 people) found lower blood pressure with nattokinase (systolic by about 3.5 mmHg, diastolic by about 2.3 mmHg), a slight rise in blood sugar, and no lowering of cholesterol; at lower total doses, total and LDL cholesterol were higher than with placebo (Li 2023).
Safety: no notable side effects were reported in the trials in the meta-analysis (Li 2023). The sources here do not describe drug interactions.
We could not find a single published half-life or time to peak for nattokinase that applies to a supplement dose, so we do not list one.
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