In the human diet, vitamin B12 is supplied primarily by animal products, since plant foods (with minor exceptions) don't contain it. It can be stored in the body up to three years before being depleted. A diet low in B1 and high in folic acid (such as a vegetarian diet) often hides a vitamin B12 deficiency. Symptoms of B12 deficiency may take more than five years to appear after body stores have been depleted. B12 prevents anemia by forming and regenerating red blood cells. It lowers the risk of heart attacks, promotes growth in children, increases energy, maintains a healthy nervous system, relieve irritability, improves concentration, memory and balance. A few Symptoms of B12 deficiency are neurological disorders, pernicious anemia, body odor, hair loss, heart palpitation, menstrual problems, mouth sores and cracks, and nervousness.