Folate is a vitamin. You need folate for many important processes inside your body, including making red blood cells. If you have a short supply of folate, your body won't make as many red blood cells, they will be abnormally large in size and won't last as long as they should. If you don't have enough red blood cells, the tissues and organs of your body may not be getting enough oxygen. This leads to the symptoms of anaemia.
Attribution: BUPA