Infants iron needs

Several years ago, New Zealand clinics regularly gave iron supplements to infants soon after birth. However, the incidence of certain bacterial infections was eight times higher in treated than in untreated infants. Presumably, the presence of more iron in the blood than absolutely necessary makes it easier for bacteria to obtain the iron needed for growth and reproduction. 

A bacterium that infects the blood requires a source of iron if it is to grow and reproduce. The bacterium excretes a siderophore into the blood to compete with transferrin for the iron it holds. The formation constants for iron binding are about the same for transferrin and siderophores. The more iron available to the bacterium, the more rapidly it can reproduce, and, thus, the more harm it can do. Several years ago. New Zealand clinics regularly gave iron supplements to infants soon after birth. However, the incidence of certain bacterial infections was eight times higher in treated than in untreated infants. Presumably the presence of more iron in the blood than absolutely necessary makes it easier for bacteria to obtain the iron needed for growth and reproduction. 

The calcium content of human milk is only about 30 mg per 100 ml, but, provided that the volume produced by the mother is sufficient, the infant s need will be covered. Milk is low in iron but infants accumulate a store of iron during intrauterine life, and this is usually sufficient for the first 4-6 months of independent existence. After this time it is important to supplement the milk diet with iron-containing foods such as strained meat and vegetables. Milk is also relatively deficient in vitamins C and D. The vitamin C content of breast milk is usually adequate, but infants fed on cow s milk may need a supplementary source. Although fresh orange juice and rose hip syrup are good sources, it is undesirable to accustom children to sweet drinks at an early age since later on these can have disastrous effects on the teeth. 

Dietary recommendations for infants are based on the iron content and bioavailability of human milk. The iron in infant formula is much less bioavailable (10%) than that of human milk and is thus present in greater concentrations than that of human milk. Infants who are not breast-fed should consume iron-fortified formula. Complementary foods offered after 6 months of age can potentially meet iron needs if they have a high content of meat and ascorbic acid. This is rarely the case in developing or developed countries, and fortified infant cereals and iron drops are often introduced at this time in developed countries. In developing countries where diets are poor in bioavailable iron, iron-fortified weaning foods are not commonly consumed, and iron supplements are rarely given to infants and children. 

Low-birth-weight infants Low-birth-weight infants are born with low iron stores and have higher iron requirements for growth. Their iron needs cannot be met from breast milk alone, and, therefore, they are a priority target for iron supplementation. 

One of the most effective and widespread methods of preventing this deficiency is the use of iron-fortified formulas. The iron levels in iron-fortified formulas are approximately ten times the concentration found in human milk. The controversies concerning human milk versus formulas or cow s milk is the availability of the iron. The iron in human milk is stated to be quite bioavailable, but questions arise concerning the need for iron supplements for Infants who are exclusively breast-fed. Further unanswered question or questions is the mechanism involved in human milk which causes it to have a high bioavailability. Some data and theories... 

The analysis of human milk for the distribution of iron into the various components found iron in three fractions of lipid, low molecular weight form and lactoferrin (16). The total concentration of milk iron varied from 0.26 to 0.73 mg/ml with 15 to 46% of the iron bound to the lipid fraction, and 18 to 50% found in a low molecular weight fraction. Surprisingly, only a small amount of iron was bound to the lactoferrin, which was saturated at 1-4%. These results even further complicate the role of lactoferrin in iron absorption by infants. Further experimental work needs to be done to define the role of lactoferrin in iron absorption, if any at all. 

Copper was also shown to be essential in the early 1900s. Copper is needed for the absorption and mobilization of iron, so a deficiency of copper causes a type of anemia that is difficult to distinguish from iron deficiency anemia. Copper is also needed for the cardiovascular system, bone, brain, and nervous system. Premature and malnourished infants are particularly susceptible to developing copper deficiency, in part because milk is a poor source of copper. Whole grains, legumes, and nuts are the major dietary sources of copper. 

IDA is a leading cause of infant morbidity and mortality in the world. The age of the child can yield some clues to the etiology of the anemia. Age- and sex-adjusted norms need to be utilized in interpretation of lab results in pediatric patients. Primary prevention of IDA is the goal. A therapeutic trial of oral iron is the standard of care. EPO may be used in anemia of prematurity (AOP). 

AOP is usually treated with red blood cell transfusions. Prema-tnre infants fed human milk need 2 mg/kg per day iron snpplemen-tation. EPO may be nsed in AOP, keeping in mind that EPO pharmacokinetics are inflnenced by the developmental age of the infant. EPO has limited efficacy in decreasing the reqnirement for transfn-sions, making it a controversial treatment approach. Infants on fnU enteral feedings treated with EPO need iron supplements in doses of 6 mg/kg per day. 

In addition to its role in transporting oxygen, iron has many other roles in the human body. Iron is important for the function of various enzymes, and allows cells to use glucose to release energy. Certain areas of the brain contain significant amounts of iron, which indicates that this metal is needed for normal brain function. Some researchers theorize that iron deficiency in infants and young children can slow mental development. The liver is also rich in iron. In fact, this organ stores excess amounts of the metal. 

IRON REQUIREMENTS AND THE AVAILABILITY OF DIETARY IRON Iron requirements are determined by obligatory physiological losses and the needs imposed by growth. Thus, adult men require only 13 /ig/kg/day ( 1 mg of iron), whereas menstruating women require 21 /ig/kg/day (-1.4 mg). In the last two trimesters of pregnancy, requirements increase to -80 /ig/kg/day (5-6 mg), and infants have similar requirements due to their rapid growth. These requirements (Table 53-3) must be considered in the context of the amount of dietary iron available for absorption. 

Requirements for iron vary according to age and gender. Infants and adult men need 10 mg per day infants are bom with a three- to six-month supply. Children and women (ages 16 through 50) need 15 to 18 mg per day. Women lose 20 to 23 mg of iron during each menstrual period. Pregnant and lactat-ing women need more than 18 mg per day. After a blood loss,... 

This review will focus first on the effect of providing total parenteral nutrition (TPN) on the outcome of various nutrient-depleting diseases in infants, then on a discussion of the need for, and metabolism of, new essential nutrients which are recommended for inclusion in TPN regiments biotin, carnitine, zinc, copper, iron, and others. 

Iron is stored in the body as ferritin and haemosiderin. These give protection from the effects of sudden loss as, for example, after a haemorrhage. In women they provide for the needs of the developing fetus and newborn infant. Ferritin is a reddish brown high molecular weight water-soluble protein which contains variable amounts of ferric iron and is found in greatest amount in the liver, spleen and bone marrow. 

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