<P> Supplementation is recommended to prevent deficiency in vegetarians who are pregnant . Once identified it is easily treated with supplementation by mouth or injection . Excess vitamin B among those who are otherwise healthy is thought to be safe . Some cases may also be helped by treating the underlying cause . Other cases may require ongoing supplementation as the underlying cause is not curable . Vitamin B deficiency is common . It is estimated to occur in about 6% of those under the age of 60 and 20% of those over the age of 60 . Rates may be as high as 80% in parts of Africa and Asia . </P> <P> Vitamin B deficiency can lead to anemia and neurologic dysfunction . A mild deficiency may not cause any discernible symptoms, but as the deficiency becomes more significant, symptoms of anemia may result, such as weakness, fatigue, light - headedness, rapid heartbeat, rapid breathing and pale color to the skin . It may also cause easy bruising or bleeding, including bleeding gums . GI side effects including sore tongue, stomach upset, weight loss, and diarrhea or constipation . If the deficiency is not corrected, nerve cell damage can result . If this happens, vitamin B deficiency may result in tingling or numbness to the fingers and toes, difficulty walking, mood changes, depression, memory loss, disorientation and, in severe cases, dementia . </P> <P> The main syndrome of vitamin B deficiency is pernicious anemia . It is characterized by a triad of symptoms: </P> <Ol> <Li> Anemia with bone marrow promegaloblastosis (megaloblastic anemia). This is due to the inhibition of DNA synthesis (specifically purines and thymidine) </Li> <Li> Gastrointestinal symptoms: alteration in bowel motility, such as mild diarrhea or constipation, and loss of bladder or bowel control . These are thought to be due to defective DNA synthesis inhibiting replication in a site with a high turnover of cells . This may also be due to the autoimmune attack on the parietal cells of the stomach in pernicious anemia . There is an association with GAVE syndrome (commonly called watermelon stomach) and pernicious anemia . </Li> <Li> Neurological symptoms: Sensory or motor deficiencies (absent reflexes, diminished vibration or soft touch sensation), subacute combined degeneration of spinal cord, seizures, or even symptoms of dementia and or other psychiatric symptoms may be present . Deficiency symptoms in children include developmental delay, regression, irritability, involuntary movements and hypotonia . </Li> </Ol>

A severe vitamin b12 deficiency results in what form of anemia