Wheat grass is a supplement that is commonly seen in juice bars and health food stores. Most known for its ability to strengthen the immune system, wheat grass is a hybrid plant from the wheat family. Grown either outside or indoors from wheat berries (seeds of wheat) this young grass is considered to be gluten-free (compared to mature wheat grass which is ready to produce new seeds). Wheat grass is rich with enzymes, chlorophyll, iron, vitamins K, A, C, B and protein.