Vitamin B12 or cobalamin is a water-soluble vitamin and one of the B-vitamin complex; “Two reactions are known to require cobalamin as coenzyme. One is the rearrangement of methylmalonyl-coenzyme A (CoA) to succinylCoA in propionate metabolism by methylmalonyl-CoA mutase in mitochondria. The other is the cytosolic transmethylation of homocysteine by 5-methyl-tetrahydrofolate to methionine by methionine synthase. The most frequent clinical expression of cobalamin deficiency is megaloblastic anaemia. Independent of megaloblastic anaemia, neurological dysfunction is another clinical feature of cobalamin deficiency.” (EFSA NDA. 2015c).