Info about Vitamins
Vitamin B6 Deficiency
PLP, the most active coenzyme form of vitamin B6 is essential for numerous metabolic reactions, including the initial regulatory step of heme biosynthesis involving d-aminolevulinic acid, the precursor of Porphobilinogen.
The typical features of anemia resulting from pyridoxine deficiency have been described as hypochromic, microcytic, and hyperferremic, with bone marrow showing erythroid hyperplasia and maturation arrest with predominantly basophilic normoblasts. Malnourished patients with hypochromic anemia respond to vitamin B6 supplementation but are unresponsive to iron therapy. Complete recovery from anemia with normal hemoglobin levels can be achieved by adequate pyridoxine therapy, but not by Fe or other vitamins or minerals.
Some researchers have tried to illustrate that the association between pyridoxine and the development of sideroblastic anemia involves the defective conversion of pyridoxine to PLP. However, there was no evidence of low erythrocyte pyridoxine kinase among patients with sideroblastic anemia or there was no deficiency of vitamin B6. The relationship between pyridoxine deficiency and sideroblastic anemia therefore warrants further investigation.
Vitamin B6 deficiency has also been reported among patients with sickle cell anemia, who responded well to PLP supplementation. PLP binds specifically to the amino terminus of the b chain of deoxyhemoglobin, and high levels of PLP may be an active inhibitor of erythrocyte ‘sickling’ in vitro. In addition, PLP may increase the affinity of hemoglobin-S to oxygen and, at high concentrations, inhibits the gelation of heoxyhemoglobin-S and reduces the number of sickled erythrocytes. However, in-vivo studies have not proven that vitamin B6 supplementation increases red blood cell counts or improves hemoglobin status.
Although isolated vitamin B6 deficiency is rare, some populations such as users of some oral contraceptives, amphetamines, isoniazid, chlorpromazine, and reserpine, as well as alcoholics have developed an anemia that can be easily corrected by therapeutic doses of vitamin B6.