Doctor's Best Natto-Serra is a combination of two natural enzymes serrapeptase and nattokinase, and supports healthy immune response and supports healthy circulation. Nattokinase, a fibrinolytic enzyme, breaks down blood clotting fibrin while Serrapeptase (serratiopeptidase) is a protein-digesting enzyme isolated from the friendly bacterium Serratia E-15 Doctor's Best uses serrapeptase made with Serrateric, a superior alternative to enteric coating that protects the enzyme until it reaches the intestines for optimal absorption. Nattokinase is derived from Natto , a fermented soy food popular in Japan for centuries. Gluten Free, Non-GMO, Vegetarian, Vegan What is Doctor's Best Natto-Serra? Doctor's Best Natto-Serra supports healthy immune response and supports healthy circulation. It is a combination of two natural proteolytic enzymes, serrapeptase and nattokinase. Serrapeptase (serratiopeptidase) is a protein-digesting enzyme isolated from bacteria isolated from the intestine of silk worms (Serratia E-15). The serrapeptase is formulated with Serrateric, a superior alternative to enteric coating that protects the enzyme until it reaches the intestines for optimal absorption. Nattokinase is derived from Natto , a fermented soy food popular in Japan for centuries. How does it work? Natto kinase is an enzyme that is found in traditional Japanese soy cheese that is also known as natto. Natto has been shown to exhibit a fibrin lytic effect in the blood stream. It has the capability to break down blood clots. Nattokinase was discovered I 1980 by a doctor from Miyazaki Medical College in Japan. Since its discovery, the cardiovascular effects of Nattokinase have been studied in many countries. Serrapeptase has other applications. Serrapeptase is an immunologically active enzyme. It can bind itself to the alpha 2 macroglobulin in our plasma where it is shielded from the immune system while retaining its enzymatic activity, and in this way it is transferred to the sites where it is needed in the body. It is this same type of specific action that allows silkworms to eat its own protective cocoon, digest it without any side effects.