Nattokinase is believed to be a blood thinner and can theoretically protect against strokes, heart attacks and other cardiovascular diseases caused by blood clots, according to WebMD. Very little information is known about nattokinase's other potential benefits, but when taken through natto, it is high in vitamin K, reports About.com.
Natto's supposed cardiovascular health benefits stem from nattokinase, states WebMD. Natto is made from boiled soybeans fermented with Bacillus subtilis natto, resulting in a cheesy, salty, sticky food. It is very popular in Japan and typically served over rice, usually eaten for breakfast, according to About.com. Nattokinase is also sold in supplement form for people who dislike the strong smell and taste.
Natto and nattokinase are old folk remedies in Japan, believed to treat or cure heart disease, high blood pressure, strokes, hemorrhoids and numerous other blood-related diseases, reports WebMD. However, as of 2015 there is no scientific evidence supporting these claims, though it is generally thought to be safe to consume regularly. There is no exact recommended dosage.
In light of nattokinase's purported blood-thinning abilities, people with blood diseases should not take nattokinase in any form, cautions About.com. Patients taking any medication that already thins the blood should not take nattokinase unless cleared by their doctor. Its effects on pregnant women have not been studied.