L-arginine is considered essential because it's highly important for many functions yet usually present in low quantities, especially as someone gets older. One of the biggest benefits of l-arginine is its ability to improve blood flow and circulation. In the body, l-arginine is converted into nitric oxide, which causes blood vessels to open wider. This has multiple benefits, including improving immune function, detoxification and brain power. Another important aspect of l-arginine is that it stimulates the production of certain hormones, especially beneficial growth hormones and insulin that help usher glucose into cells to be used for growth and energy output. It's also believed to enhance physical performance, stamina and strength.