An amino acid is a precursor to histamine, released by the immune system during an allergic reaction. It helps protect nerve cells and is needed for tissue growth and repair. It is necessary for the production of red and white blood cells. It helps remove heavy metals, lowers blood pressure, helps stimulate gastric juices, is used to help treat rheumatoid arthritis, and in conjunction with vitamins B3 and B6, helps improve sexual functioning and pleasure.