Other ingredients
Nattokinase
Names you may see: natto enzyme fermented soy fibrinolytic units FU
The quick take
Nattokinase is an enzyme associated with natto, a fermented soybean food.
A closer look
What forms will I see on a label?
Labels may state enzyme activity in fibrinolytic units (FU). Milligrams alone do not describe activity, and natto food is not identical to an isolated enzyme supplement.
Why people use it
People use it for circulation and cardiovascular-support goals.
These are common goals and marketing uses. The evidence section below explains what research supports.
What does the evidence tell us?
Small studies suggest possible blood-pressure effects, but benefits remain uncertain. It is not an established way to prevent or treat blood clots.
What should I know before using it?
Bleeding risk is important, especially with aspirin, anticoagulants or bleeding disorders. Do not replace prescribed blood thinners with nattokinase. Seek medical advice with a clotting history or planned surgery; natto allergy is also relevant.
Sources & further reading
Content reviewed: September 30, 2026
General educational information. Follow the product label and seek individual advice when needed.