M.D. Cesar Fraga, a professor at the University of Buenos Aires, reported at the annual meeting of the American Association for the Advancement of Science in Washington, D.C., that two hours after eating chocolate, people had high blood levels of flavonoids, antioxidant chemicals that help prevent heart attacks. For gosh sakes, don't go out and eat bags of chocolate just because of these studies by respected investigators.
All plants contain phytochemicals that can help to prevent disease.
Sulforophane in broccoli prevents cancer, allicin in garlic and capsaicin in peppers prevent heart attacks and so forth. Edible plants also contain chemicals that can harm you if eaten in large quantities. We are not usually harmed by our food supply because we do not eat huge amounts of any one plant. Chocolate comes from plants and does contain beneficial phytochemicals, but pure chocolate tastes very bitter. To make chocolate taste good, it is prepared with lots of sugar and fat.