Natto, which is boiled fermented soybeans, produces an enzyme called nattokinase that reduces the body's blood clotting ability and acts as a blood thinner to reduce clots, according to WebMD. Nattokinase may protect patients against heart attacks, strokes, deep vein thrombosis and other blood clot-related conditions. People have used natto for centuries as a folk remedy for cardiovascular diseases. Dr. Hiroyuki Sumi discovered the effects of nattokinase while he was a researcher at the University of Chicago.
Study participants with high blood pressure who took daily doses of nattokinase for eight weeks experienced lowered blood pressure, notes WebMD. Some evidence shows that when individuals take doses of 150 milligrams of nattokinase combined with pycnogenol before and after long airplane flights, they may lower their likelihood of developing blood clots in their legs during the flights.
Natto, a soy food that is popular in Japan, is the only source of the protein nattokinase, which accelerates biochemical reactions, explains WebMD. It is likely safe to take nattokinase orally in quantities normal for consuming food. Scientists do not have enough information about nattokinase to establish dosage ranges for it. Individuals planning to take nattokinase should discuss appropriate dosages with their doctors or other health care professionals. People taking nattokinase should stop taking it at least 14 days before undergoing surgery, because the enzyme might cause excessive bleeding.