Anemia is a condition wherein your body lacks a sufficient amount of red blood cells, which carry oxygen to the different parts of your body. As you may know, a consistent supply of oxygenated blood is necessary for the organ systems to function very well. Â With the presence of anemia, your body doesnâ€™t function optimally. There are many types of anemia. One of the most tackled one is B12 deficiency anemia. This type of anemia is also referred to as macrocytic anemia, which is basically a decrease in the number of red blood cells because of the lack of vitamin B12.