Ultra StrengthEnteric Coated Nattokinase and Serrapeptase is intended to provide nutritive support for normal, healthy blood flow and circulation. Nattokinase is a fibrinolytic enzyme extracted from the traditional Japanese food natto. Serrapeptase is a non-animal, proteolytic enzyme derived from a controlled fermentation of the bacterial strain Serratia spp. Solaray Nattokinase and Serrapeptase is enteric coated, which helps the capsules survive the stomach acid and pass into the small intestine.