Vitamin E is an antioxidant that protects body tissue from damage caused by substances called free radicals. These radicals can damage cells, tissues, and organs, and are believed to play a role in certain conditions related to aging. The body also needs vitamin E to help keep the immune system strong against viruses and bacteria. Vitamin E is also important in the formation of red blood cells and helps the body use vitamin K. It also helps dilate blood vessels and prevent blood from clotting inside them. Cells use vitamin E to interact with each other and carry out many important functions.