Seeds are not perfect foods. Legumes in particular contain defensive chemicals— lectins and protease inhibitors—that can cause malnourishment and other problems. Fortunately, simple cooking disarms these defenses. The fava bean contains amino-acid relatives that cause serious anemia in susceptible people, but both the bean and the susceptibility are relatively rare. Two other problems are more common.
From the book On Food and Cooking (2nd edition) by Harold McGee. © 2004 Harold McGee. By permission of Scribner, a division of Simon & Schuster, Inc.