Excess fibrin can lead to heart attack, stroke, senile dementia.

The protein fibrin is a critical player in a wide array of metabolic reactions. On the one hand, it is essential to wound healing as fibrin is released to initiate coagulation that seals off the injury site. On the other hand, fibrin release also coats the inner walls of blood vessels to protect them from random particles in the blood and to smooth vascular walls to facilitate blood flow.

The even control of fibrin production is of utmost importance to good health. Overproduction of fibrin or insufficient rate of its breakdown is problematic as it increases blood viscosity which could form clots or thrombi which can adhere to vessel walls. These bits of fibrin can precipitate the accumulation of more fibrin and also cholesterol. As these clots increase in size they may interfere with the the smooth flow of blood, resulting in the protrusion of blood vessels. The result of these protrusions are a variety of conditions including varicose veins and/or deep vein thrombosis. Fibrin overproduction can also initiate the development of plaque which can break off and cause a coronary event. Blood clots can cause blockage of blood flow to heart muscle tissue resulting in angina and heart attack. Clots can also block blood and oxygen going to the brain which can result in senility and/or stroke.

Thrombolytic enzymes (they break down blood clots and control the laying down of fibrin) decline with age.

It is important to maintain blood at optimal viscosity. This requires the presence of enzymes that reduce the effects of excess circulating fibrin (as described above). These enzymes are called thrombolytic-they keep coagulant enzymes in check. It is common to see a decline in thrombolytic enzymes as individuals age and when inflammation of the blood vessels often increases. In fact, inflammation resulting from unchecked fibrin production is a culprit in many chronic diseases including arthritis, fibromyalgia, coronary artery disease, Alzheimer's disease, and a host of other age related afflictions. Natto, a food produced by the fermentation of soybeans, contains an enzyme with powerful fibrinolytic activity and has the ability to reduce the effects of excess fibrin.

Dr. Hiryuki Sumi, M.D, discovered that natto exhibited a strong blood clot busting activity and he named the corresponding fibrinolytic enzyme nattokinase. Nattokinase enhances the body's natural ability to fight blood clots in several different ways and has many benefits. It also enhances the body's own production of both plasmin and other clot dissolving agents. Nattokinase has been the subject of 17 studies which include two small human trials and these tests indicate that nattokinase generates a heightened ability in subjects to dissolve blood clots, a potency unmatched by any other enzyme.