In the first two months of life, a marked decrease in hemoglobin concentration is observed, with the lowest values ​​ranging from six to eight weeks, and in parallel, an increase in the mobilization of iron reserves. This autumn is known as the physiological anemia of the infant, which is not prevented by any preventive measures or is not accompanied by any anomaly.

Iron stores from birth to six months, when the baby receives only breast milk, are engaged physiological needs  a child, without requiring any form of supplementation or solid product administration. This is due to the high bioavailability of iron in human milk, while about 50% of its iron is absorbed, which compensates for its low concentration. However, this bioavailability can be reduced to 80% when a child eats other foods. Therefore, the early introduction of additional foods is considered a factor of high risk of iron deficiency anemia.

Beginning at six months, iron stores are depleted, and food begins to play a dominant role in meeting the needs of this nutrient. It is necessary that the consumption of iron was sufficient and required for this age group. From 6-12 months, iron needs a very large body weight, and the weight of a child at the end of the first year of life has tripled in relation to its weight at birth. Approximately 30% of the iron needed for erythropoiesis should be obtained from food intake, because due to its rapid growth and dependence on food as a source of this mineral, the child becomes quite susceptible to falling into negative iron balance.

This situation is different for an adult who processes about 95% of the iron needed for lysing red blood cells, and only 5% of this comes from the diet. Initially, requirements are determined by the need for absorption of iron. After that, they are converted to assess the needs for dietary iron, taking into account their bioavailability. Consumption of absorbed iron is 0. 96 mg for children from 3 months to 1 year; 0, 61 mg, from 1 to 2 years; and 0, 70 mg, from 2 to 6 years.

For some time it was believed that iron intake within or above the recommendations would be sufficient to prevent iron deficiency anemia. Therefore, several studies have failed to link total iron intake with the organic status of iron. However, taking into account the bioavailability studies of nutrients, it is recognized that it is more important than meeting the needs, attention should be paid to the amount of bioavailable iron, which is associated with stimulants and inhibitors of its use, which are present in the same meal.

Iron is present in food in two forms: heme and non-heme. Bile iron present in meat and veins has very high bioavailability and is not susceptible to inhibitory factors. The meat contains about 4 mg of iron per 100 g of food, absorbs about 40% of this nutrient.

Non-iron iron contained in cereals and vegetables, unlike animal iron, is absorbed by only 10% of the body. Absorption is not hemic form strongly depends on the various components of the diet. Therefore, limited feeding in meat, usually more common in lower income groups, therefore leads to a lower biological utilization of iron.

Evaluating the diet of children in relation to the quality and quantity of iron consumed, it is noted that there is a greater intake of iron of plant origin than of animal origin, and that a large proportion of the inadequacy of consumption of all iron is among those less than twenty-four months.

When energy and iron intake is analyzed, iron deficiency in the diet, as shown, is not associated with a calorie deficit, but with a certain dietary inadequacy in relation to the mineral. A wide variety of factors are known that facilitate and inhibit the absorption of iron. Various animal tissues, including beef, chicken, fish, goat, liver and pork, increase iron status, ensuring high availability of iron and iron. Iron absorption is not gay.

When ascorbic acid is added to food, the rapid effect on the percentage of iron absorption is remarkable. On the other hand, phytates, tannins, calcium, phosphates, eggs and other products have an inhibitory effect, because they form precipitates that are insoluble with iron, which complicates their absorption. By itself, the fiber does not affect the absorption of iron. The inhibitory effect of whole grains is also associated with the content of phytate. The inhibitory effect of calcium on iron absorption is of significant nutritional importance.

Studies on the nutritional components of food products have shown that milk supplied by milk strongly inhibits the absorption of heme iron and iron without heme. However, the mechanism of direct effects of calcium on iron absorption is still unknown. There will probably be some kind of competitive inhibition between calcium and iron with the final transfer of the intestinal mucosa to the plasma, which is done for both iron and iron without heme. The inhibitory effect of cow's milk on iron may also be due to the presence of phosphoproteins.

In egg, the phosphoproteins contained in both the yolk and white have this inhibitory effect. Although the absorption of dietary iron depends on a number of factors, such as the type of iron, organic reserves of the mineral and the combination of foods in the same food, it is possible to predict the nutrient absorption potential in each of the dishes that make up the daily diet, using the equation developed by Monsen and Balintti. This equation takes into account the iron content and potentiating factors of its absorption, present in the composition of each meal.

The sum of the values ​​found in different meals corresponds to the daily amount of iron bioavailability under normal physiological conditions. Using the equation of Monsen and Balint, Osirio confirmed the low bioavailability of iron in children 6–59 months in all age groups and geographical areas of the state of Pernambuco.

It is clear that the adequacy of energy is not necessarily a guarantee of the adequacy of iron consumption. It should also be noted that a quantitative assessment of iron consumption does not specify the adequacy of its consumption. The use of iron has a qualitative connection with the overall consumption of the diet, since specific products are necessary for its better use by the body. Thus, the study of specific dietary factors associated with iron absorption is extremely important for understanding the epidemiological picture of the problem.

Prenatal care and delivery must be effective in preventing and correcting the main health and nutritional problems of a pregnant woman, which can lead to weight loss and prematurity. Similarly, in the postpartum period, monitoring the growth and development of a baby with proper guidance on breastfeeding and complementary feeding can significantly reduce the risk of developing anemia.

There are examples, for example, in Australia and the United States, where iron deficiency is no longer a public health problem in children. preschool age, and in recent years, the level of iron deficiency has decreased, perhaps due to the improvement of the child’s health care system, increasing breastfeeding improving nutritional status and introducing adequate eating habits.

Therefore, the lack of proper care, which prevents anemia and early detection of children with iron deficiency, is considered inadequate. To this end, it is necessary for medical services to regularly integrate nutritional assistance to pregnant women and children through nutritional status assessments and food education activities, while at the same time performing laboratory diagnostics of anemia and receiving supplements to drugs  for treatment.

It is known that anemia in a pregnant woman, especially in the third trimester of pregnancy, increases the risk of birth of premature and underweight children. Low birth weight, as an indicator of malnutrition at birth, is considered the determinant of anemia, especially in children in the first year of life. Thus, stocks are depleted earlier, which makes them more dependent on foreign sources and thus facilitates the installation of anemia. On the other hand, Monteiro and Sarfark believed that low birth weight would not fully explain the early onset of anemia in the Sao Paulo municipality, since the population’s low birth weight rate was small.

The same reasoning can be applied to the state of Pernambuco, where, although there is a relationship between hemoglobin level and birth weight, this variable alone does not explain the high prevalence of anemia, especially in rural areas, where the lowest incidence is low birth weight and higher prevalence anemia among the children of the state.

Malnourished children are mostly anemic. Protein deficiency in protein-energy malnutrition leads to a decrease in hemoglobin level by 20%, which, apparently, is an adaptation of the organism to a decrease in muscle tissue. However, despite the presence of a significant reduction in malnutrition among children in Brazil, the epidemiological picture of iron deficiency anemia does not show the same trend.

Vitamin A is believed to affect iron metabolism, but this mechanism has not yet been fully clarified. It is possible that vitamin A does not directly affect the absorption of iron through the intestinal tract, but rather by mobilizing available iron reserves and using iron to form hemoglobin. Another possible mechanism is that vitamin A deficiency reduces the level of transferrin and, therefore, reduces iron transfer.

In areas where vitamin A deficiency is endemic, vitamin A supplementation or enrichment programs can help increase the organic iron content of the population. The literature on the association between iron deficiency and infections is controversial. Some authors believe that any iron deficiency suppresses immune function and increases the risk of infection, while others argue that immune status favors a weak iron deficiency. Changes caused by inflammation and infections in iron metabolism are important mixing factors when assessing the state of iron.