Cow's milk has severe adverse effects on iron nutrition among young children, most importantly is its low iron content which makes it difficult for the infant to obtain the amounts of iron needed for growth also there is the occult intestinal blood loss, that occurs in about 40% of normal infants due to cow's milk. However this loss of iron in the form of blood diminishes with increasing age and finally ceases after 1 year of age. Bus as we know that the calcium, casein, protein and minerals in cow's milk is in very high amounts, it inhibits the absorption of dietary non-heme iron and the excess has to be excreted via urine that leads to high renal solute load resulting in higher urine concentration. In such a conditions where the fluid intakes is low and external water loss is high, the renal concentrating ability of infants becomes insufficient to maintain water balance to cope up for the high water use for excretion of the high renal solute resulting in negative water balance leading to serious dehydration.