Blueberry fruit extract concentrates the whole fruit and is usually standardized for anthocyanins, the pigments that give blueberries their deep color and antioxidant properties. People often take it once or twice daily with a meal to improve absorption.
Researchers have studied blueberry components for their effects on circulation and brain function, and many people take the extract for these reasons. High doses can upset the stomach. Very large amounts may thin the blood, so anyone taking anticoagulants should talk to a doctor before using it.