There's some early evidence that nattokinase may have benefits for heart and artery health. One study shows that a nattokinase supplement lowers the risk of blood clots after long plane flights. It may help reduce narrowing of the arteries.
Other studies show that nattokinase may help lower blood pressure. However, we need more research to see if it is effective.
Optimal doses of nattokinase have not been set for any condition. Quality and active ingredients in supplements may vary widely from maker to maker. This makes it very hard to set a standard dose. Ask your doctor for advice.