Swallowed as is, grape seeds will be eliminated from the body and nothing will be absorbed. Chewed and swallowed may cause serious irritation of the gastrointestinal tract, triggering peptic ulcers and other side effects, because in addition to the beneficial health of grape seeds OPCss (anthocyanins), there are a number of unhealthy tannins and other toxic substances exist. It is better not to try it easily. (Tannins have a faint astringent flavor and can cause abdominal pain)