The vitamin for vascular health, vim, and vigour! Vitamin B-12 is commonly associated with energy because it plays a vital role in the formation of the red blood cells that deliver oxygen to all parts of the body. It also supports cardiovascular health by working with vitamin B-6 and folic acid to help control harmful homocysteine. 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.