Swanson Vitamin B-12 is an essential vitamin for overall health and well-being. It is best known for producing energy in the body and plays a vital role in the formation of the red blood cells that deliver oxygen to all parts of the body. It also works with vitamin B-6 and folic acid to help promote cardiovascular health. While adequate B-12 intake is important for everyone, supplementation may be particularly helpful for some people because the vitamin is found primarily in animal-based foods.