The dangers of nattokinase

Nattokinase, also known as natto extract, is an enzyme derived from fermented soybeans that some companies sell as a supplement meant to promote good cardiovascular health. It can have harmful side effect and it can also lead to people with serious health conditions to undertreat their disease.


Nattokinase is an enzyme extracted from natto, a form of fermented soybeans created by boiling the beans and combining them with a certain kind of bacteria. Natto is cheese-like substance that is popular as a breakfast food in Japan. Nattokinase is an extract from natto that is often made into pills and taken as a food supplement that is supposed to dissolve blood clots that can cause heart attacks and strokes.

Dangerous Side Effects and Drug Interaction

Nattokinase can cause low blood pressure. Hemophiliacs and people who suffer from other bleeding disorders should not take the supplement because these people usually have a blood defect that prevents clotting. Nattokinase could theoretically make these bleeding disorders more pronounced. Nattokinase also contains large amounts of vitamin K. If a person takes too much of this vitamin, it can decrease the effectiveness of Coumadin, a drug that hemophiliacs take to stop bleeding and bruising.

Do Not Rely on Nattokinase

The benefits are nattokinase are mostly unproven. There have been no formal clinical studies of its effectiveness.

Some Blood Clots are Good

Supposedly nattokinase works as a "fibrinolytic agent," something that dissolves blood clots and prevents heart attacks and strokes. However, not all clots in the body are bad. Blood clots are formed by blood cells known as platelets, which join together when they encounter a tear or hole in a blood vessel. Clots essentially plug these holes and stop bleeding, both internal and external.

People at Risk of Dangerous Clotting

Blood clots can be dangerous, especially if they block healthy blood vessels or break loose and travel through the blood stream only to lodge somewhere else in the body and cause bleeding or cut off blood flow. People with genetic disorders, injuries that immobilise a part of the body for a long time (which slows blood flow), or who have suffered a trauma to a blood vessel can be at risk of getting a dangerous clot. These people should consult with their doctor about the risks of clots and take prescribed medications that have been proved to work at treating their conditions. If these people also want to take nattokinase as an additional protection against clots, they should talk to their doctor about whether this is safe.