Jarrow FORMULAS d-Limonene is an essential oil that stimulates the liver"s Phase I and Phase II detoxifying enzyme systems and supports normal immune function.* Jarrow FORMULAS d-Limonene is steam-distilled from orange peel and is purified to be food grade. d-Limonene is the major constituent of several citrus essential oils (orange; lemon and lime); and naturally occurs in citrus juices. Store in a cool; dry place. Keep out of the reach of children.