Vitamin B12 is necessary for processing carbohydrates, proteins and fats and to help make all of the blood cells in our bodies. Vitamin B12 is also required for maintenance of our nerve sheaths . Vitamin B12 cannot be absorbed or used by the body until it is combined with a mucoprotein made in the stomach and called intrinsic factor . Once the B12 becomes bound to the intrinsic factor, it is able to pass into the small intestine to be absorbed and used by the body. Although enough B12 is stored in the liver to sustain a person for many years, a deficiency will cause a disorder known as pernicious anemia .
Pernicious anemia causes weakness, numbness of the extremities, pallor, fever and other symptoms.
Mouth irritation and brain damage are also common consequences of B12 deficiency. However, these very serious effects can be reversed by vitamin B12 shots. Shots are needed because the deficiency is often caused by an inability to absorb the vitamin when taken orally. As we age, our stomachs have an increasingly difficult time producing intrinsic factor. Many doctors recommend that people over 60 have their vitamin B12 levels checked, to see if a B12 shot is needed.