Iron balance and iron nutrition in infancy

At birth, the total body iron content is approximately 75 mg/kg, twice that of an adult man in relation to weight. During the first 6 mo of life, total iron body content increases slightly and exclusive breastfeeding is sufficient to maintain an optimal iron balance. Thereafter, iron body content substantially increases and the infant becomes critically dependent on dietary iron, provided by complementary foods. Numerous factors may contribute to nutritional iron deficiency in infancy, the most important being low body iron content at birth, blood loss, high postnatal growth rate, and a low amount and/or bioavailability of dietary iron. We have documented that the prevalence of iron deficiency declined in Italy as iron nutrition improved and that early feeding on fresh cow's milk is the single most important determinant of iron deficiency in infancy. Healthy full-term infants should maintain optimal iron balance by consuming a good diet, which can be summarized as follows: breastfeeding should be continued exclusively for at least 5 mo and then together with complementary foods containing highly bioavailable iron; infants who are not breastfed or are partially breastfed should receive an iron-fortified formula, containing between 4.0 and 8.0 mg/L iron, from birth to 12 mo of age; fresh cow's milk should be avoided before 12 mo of age.     

A cohort study of term infants from Vilnius, Lithuania: feeding patterns

AIM: To present infant feeding patterns and to relate these to selected biological and social factors. METHODS: One hundred and ninety-two infants born at four delivery departments were followed prospectively from birth to 12 mo of age. Their parents were asked to tick weekly if the infant received items on a list of the most common infant foods and drinks, including breast milk. RESULTS: All infants started breastfeeding. Median duration of exclusive breastfeeding was 0.5 mo, and 3.75 mo for "any breastfeeding". Mothers who were older (>25 y), better educated (>11 y) and non-smokers breastfed significantly longer (median 4 mo). Median introduction of cow's milk was 8 (range 2-12) mo. At the age of 12 mo, 78% of infants received cow's milk and 58% of infants received cow's milk as the sole source of milk. Mothers who were younger (<21 y) and less educated (<12 y) introduced cow's milk significantly earlier. Mean (SD) start of solids was 3.4 (1.0) mo. Longer duration of breastfeeding was the only factor significantly associated with the later start of solids. Ninety-two percent of infants were introduced to fresh cheese before 12 mo. Additional liquids were widely given both to breastfed and non-breastfed infants. CONCLUSIONS: Compliance with the current infant feeding recommendations is not sufficient. Breastfeeding rates are low. Use of high-protein products is widespread. More effort should be made to educate young, less educated and smoking mothers.     

Nutrition, growth, and complementary feeding of the breastfed infant

Although additional research is needed on many of the issues discussed herein, the following conclusions are well substantiated by the evidence available to date: Breast milk alone can meet nutrient needs during the first 6 months, with the possible exception of vitamin D in certain populations and iron in infants of relatively low birth weight. Complementary foods offered before 6 months of age tend to displace breast milk and do not confer any growth advantage over exclusive breastfeeding. Breast milk continues to provide substantial amounts of key nutrients well beyond the first year of life, especially protein, fat, and most vitamins. Breastfed infants tend to gain less weight and usually are leaner than are formula-fed infants in the second half of infancy. This difference does not seem to be the result of nutritional deficits but rather infant self-regulation of energy intake. New growth charts based on infants breastfed throughout the first year of life are being developed by WHO. The nutrients most likely to be limiting in the diets of breastfed infants are minerals, such as iron, zinc, and calcium. Using the following guidelines can help to ensure that the nutrient needs of the breastfed child are met: Continue to breastfeed as often as the infant desires. Aim for a variety of complementary foods, with fruits, vegetables, and animal products (e.g., meat, fish, poultry, or egg) offered daily. Iron-fortified cereals and meats can provide adequate iron. Calcium can be obtained from cheese, yogurt, and other dairy products (although fresh cow's milk is not recommended before 12 mo). Avoid giving too much juice. Be alert to any signs that the child's appetite, growth, or development is impaired. When in doubt, a balanced vitamin-mineral supplement is advisable. Make mealtimes enjoyable.     

Progress in the Prevention of Iron Deficiency in Infants

ABSTRACT. Our present success in preventing iron deficiency in infants is based on a gradual growth in our understanding of iron nutrition. It became recognized that full term infants only become vulnerable to iron deficiency after about 5 months of age, and to a lesser degree if they are breast-fed. The specific foods in which iron is provided during infancy were found to be more important in determining iron absorption than the actual amount of iron in the diet. Experience has also shown that fortification of infant foods is more reliable and cost effective than providing iron medication. Our current approaches to preventing iron deficiency in infants include: 1) maintaining breast feeding for at least 6 months, if possible; 2) using an iron-fortified infant formula if a formula is used and using formula in preference to cow's milk; 3) using iron-fortified infant cereal as one of the first solid foods; and 4) providing supplemental iron for low birth weight infants.     

Iron and breastfeeding

Given the importance of iron nutrition during the first year of life, there are surprisingly few true, randomized, controlled studies addressing this issue; however, it seems that iron deficiency is unlikely in full-term, breastfed infants during the first 6 months of life because these infants' body iron stores are sufficient to meet requirements. After this time, many infants exhaust their iron stores and become dependent on a secondary dietary iron supply. Although iron deficiency is a significant nutritional problem worldwide, most of the adverse effects of iron deficiency in this age group are hypothetical and rely on extrapolation from animal studies or studies at different ages. This, however, also is true of most of the adverse effects of iron excess in this age group. Given this uncertainty, it seems prudent to use the lowest dose of iron that prevents iron-deficiency anemia. Currently, the best evidence is that this is achieved by prolonged breastfeeding, avoidance of unfortified formulas and cow's milk, and the introduction of iron-fortified and vitamin C-fortified weaning foods at approximately 6 months of age. Despite much research, there are many areas of uncertainty regarding iron supplementation of infants, including that: 1. The optimal age for introducing iron-fortified supplemental foods is poorly defined and should be further evaluated. 2. The natural history of iron deficiency and iron-deficiency anemia during the first year of life is unclear, as are the possible long-term effects of this, especially on developmental outcome. 3. The biologic variability among infants and among their mothers that allows many infants who do not receive iron-fortified foods to prevent iron deficiency while receiving only human milk throughout the first year of life is intriguing and warrants additional study. 4. The iron requirements of small-for-gestational-age, term infants are unknown. Their iron requirements are likely to be higher than those of average term infants, but whether iron supplements are required is unclear. 5. The optimum amount of dietary iron in the weaning diet needs to be further defined. Similarly, the optimal source and amount of iron in infant formulas given to infants who receive a mixture of human milk and formula is unclear.     

Influence of breastfeeding and complementary food on growth between 5 and 10 months

The aim of this study was to examine the nature of the association between breastfeeding, complementary feeding and growth in a random sample of infants from Denmark, where the prevalence of breastfeeding is high. A semiquantitative food frequency questionnaire and a questionnaire on breastfeeding duration and on weight and length measurements taken at the infant welfare visit at 5 and 10 months were sent to 590 families with 10-month-old infants. A total of 339 infants with complete growth data were included in the analyses. When controlling for mid-parental height and birth weight infants breastfed for ≥ 7 months gained 198 g less in weight ( p < 0:01) and 7 mm less in length ( p < 0:01) during the period from 5 to 10 months than infants breastfed for < 7 months. Controlling for these effects, the 10% of the sample with the highest protein intake (i.e. ≥16 energy percentage) gained 262g more than those with a lower protein intake ( p = 0:03). Infants breastfed for ≥ 7 months received significantly less cow's milk ( p < 0:01), and fewer meat-containing dishes ( p < 0:05) and sweets or cakes ( p < 0:01), which may partly explain the effect of breastfeeding. The long-term consequences of this moderate difference in growth velocity are unknown and the findings should not be used to advocate against breastfeeding during late infancy.     

Duration of exclusive breastfeeding is a positive predictor of iron status in 6‐ to 10‐month‐old infants in rural Kenya

The prevalence of iron‐deficiency anemia (IDA) is high in infants in Sub‐Saharan Africa. Exclusive breastfeeding of infants to 6 months of age is recommended by the World Health Organization, but breast milk is low in iron. Some studies suggest exclusive breastfeeding, although beneficial for the infant, may increase risk for IDA in resource‐limited settings. The objective of this study was to determine if duration of exclusive breastfeeding is associated with anemia and iron deficiency in rural Kenyan infants. This was a cross‐sectional study of 6–10‐month‐old infants (n = 134) in southern coastal Kenya. Anthropometrics, hemoglobin (Hb), plasma ferritin (PF), soluble transferrin receptor (sTfR), and C‐reactive protein were measured. Body iron stores were calculated from the sTfR/PF ratio. Socioeconomic factors, duration of exclusive breastfeeding, nature of complementary diet, and demographic characteristics were determined using a questionnaire. Mean ± SD age of the infants was 7.7 ± 0.8 months. Prevalence of anemia, ID, and IDA were 74.6%, 82.1%, and 64.9%, respectively. Months of exclusive breastfeeding correlated positively with Hb (r = 0.187; p < .05) and negatively with sTfR (r = ?0.246; p < .05). sTfR concentrations were lower in infants exclusively breastfed at least 6 months compared with those exclusively breastfed for less than 6 months (7.6 (6.3, 9) vs. 8.9 (6.7, 13.4); p < .05). Controlling for gender, birth weight, and inflammation, months spent exclusively breastfeeding was a significant negative predictor of sTfR and a positive predictor of Hb (p < .05). The IDA prevalence in rural Kenyan infants is high, and greater duration of exclusive breastfeeding predicts better iron status and higher Hb in this age group.     

The significance of iron in development and nutrition of infants. II. Prevention of iron deficiency

The symptoms and consequences of iron deficiency in the child are described as found in the literature. The role of iron in immune processes is presented and it is noted that there is no proof for the theory of the development of bacterial infections as a result of giving oral iron supplements. The influence of breast milk and cow milk on the intestinal uptake and loss of iron is discussed. Feeding infants formulae or milk-substitute formulae after cessation of breastfeeding prevents the increased blood loss in the digestive tract, which results from the introduction of cow's milk. The iron content of selected Polish infant formulae, follow-on formulae and milk-substitute formulae available on the market are given and compared with FAO, WHO, ESPGAN and EC recommendations. Results of the authors' own researches on the iron content of selected Polish powdered whole cow's milks are presented. The measurements, made by atomic absorption spectroscopy (AAS), showed that iron content of whole powdered milks ranged from 0.23 to 1.19 mg/dm3. The values do not vary significantly from those in the literature on the iron content of unboiled cow's milk. It is shown that up to the point of the doubling of birth weight, formula-fed infants should be fed modified milk containing at least 2 mg/dm3 of iron. Thereafter infants should receive milk containing at least 7 mg/dm3 of iron.     

Feeding practices of infants through the first year of life in Italy

AIM: To investigate infant feeding practices through the first year of life in Italy, and to identify factors associated with the duration of breastfeeding and early introduction of solid foods. METHODS: Structured phone interviews on feeding practices were conducted with 2450 Italian-speaking mothers randomly selected among women who delivered a healthy-term singleton infant in November 1999 in Italy. Interviews were performed 30 d after delivery and when the infants were aged 3, 6, 9 and 12 mo. Type of breastfeeding was classified according to the WHO criteria. RESULTS: Breastfeeding started in 91.1% of infants. At the age of 6 and 12 mo, respectively, 46.8% and 11.8% of the infants was still breastfed, 68.4% and 27.7% received formula, and 18.3% and 65.2% were given cow's milk. Solids were introduced at the mean age of 4.3 mo (range 1.6-6.5 mo). Introduction of solids occurred before age 3 and 4 mo in 5.6% and 34.2% of infants, respectively. The first solids introduced were fruit (73.1%) and cereals (63.9%). The main factors (negatively) associated with the duration of breastfeeding were pacifier use (p < 0.0001), early introduction of formula (p < 0.0001), lower mother's age (p < 0.01) and early introduction of solids (p = 0.05). Factors (negatively) associated with the introduction of solids foods before the age of 3 mo were mother not having breastfed (p < 0.01), early introduction of formula (p < 0.01), lower infant bodyweight at the age of 1 mo (p = 0.05) and mother smoking (p = 0.05). CONCLUSION: The duration of breastfeeding in Italy is still inadequate, as well as compliance with international recommendations for timing of introduction of complementary foods. National guidelines, public messages and educational campaigns should be promoted in Italy.     

Iron Deficiency in the Weanling: a Nutritional Problem on the Way to Resolution

ABSTRACT. The rapidly growing weanling becomes vulnerable to iron deficiency when neonatal iron stores have been consumed after the first few months following birth. Whether the infant will progress from the harmless condition of depleted iron stores to the physiological handicaps associated with iron deficiency depends on the selection of foods during the period of weaning. Consumption of fresh cow's milk and of unfortified cow's milk formulas and cereal products predispose to iron deficiency. Breast feeding, iron- and ascorbic acid-fortified cow's milk formulas and cereals, and the use of ascorbic acid-rich foods and meat decrease the likelihood of iron deficiency. Recent changes in infant feeding practices in the United States have been associated with a marked decline in iron deficiency anemia. A challenge for the future will be to extend this success, particularly to developing countries.     

Infantile colic and small intestinal function: a nutritional problem?

Approximately 25% of infants with moderate or severe colic (crying > 3 h d(-1)) have a cow's milk-dependent colic. The author recommends a strict cow's milk-free diet for the mother (with an extra supplement of calcium) in breastfed infants and a casein-hydrolysate formula for formula-fed infants. With this dietary regimen, there will be no nutritional problems. Later in infancy a relatively high proportion of the infants will continue to show an adverse reaction to cow's milk and will also develop allergies to other foods. Several signs (e.g. increased macromolecular absorption, increased motilin levels in serum, increased breath hydrogen excretion, decreased gallbladder contractility) indicate an abnormal intestinal function in colicky infants. The nature of this abnormality is still unknown.     

Breast vs. bottle: differences in the growth of Croatian infants

The aim of the paper was to compare the growth of rural Croatian infants with 2000 Centers for Disease Control and Prevention (CDC) growth standards and to evaluate the potential preventive influence of breastfeeding on the development of obesity in infancy. Two hundred three infant-mother pairs from Baranja, an Eastern region of Croatia, were enrolled into this study. Retrospective evaluation of infants' medical charts was used to obtain anthropometric data recorded at the birth, 1, 3, 6, 9 and 12 months of age. Infant feeding mode was self-reported by mothers. Breastfed infants gained the least weight of all observed groups. Up to 6 months of age, formula fed infants had the highest weight gain and after 6 months of age, mixed milk fed infants had the highest weight gain. At 12 months of age, 6.4% of all study infants and 7.6% of mixed milk fed infants were at risk of overweight, while the same risk for the group of breastfed infants was 4%. Most of the study infants achieved higher values of body mass and length than the child growth standards. Exclusively breastfed infants, in comparison with other study groups (formula fed infants, mixed milk fed infants and cow's milk fed infants), had lower weight-for-length z-scores during the first year, which suggests that breastfeeding may have a preventive impact on obesity development.     

Infantile colic and small intestinal function: a nutritional problem?

Approximately 25% of infants with moderate or severe colic (crying > 3 h d⁻¹) have a cow's milk-dependent colic. The author recommends a strict cow's milk-free diet for the mother (with an extra supplement of calcium) in breastfed infants and a casein-hydrolysate formula for formula-fed infants. With this dietary regimen, there will be no nutritional problems. Later in infancy a relatively high proportion of the infants will continue to show an adverse reaction to cow's milk and will also develop allergies to other foods. Several signs (e.g. increased macromolecular absorption, increased motilin levels in serum, increased breath hydrogen excretion, decreased gallbladder contractility) indicate an abnormal intestinal function in colicky infants. The nature of this abnormality is still unknown.     

Optimizing the introduction of complementary foods in the infant's diet: a unique challenge in developing countries

Being one of a series of technical support papers pertaining to the South African paediatric food-based dietary guidelines, this paper specifically deals with two of the guidelines proposed for the age group 6-12 months regarding the introduction of complementary foods in the infant's diet. Studies have shown that most of South African infants receive solid foods at the age of 4 months or earlier while only a small percentage are breastfed exclusively until 6 months. The untimely and inappropriate introduction of complementary foods have been shown to be risk factors for both under- and over-nutrition with resultant under- or overweight, stunting and micronutrient deficiencies. Optimal timing for the introduction of complementary foods will depend on the infant's physiological and developmental status. Small, frequent meals of easily digestable, smooth, semisolid nutrient- and energy-dense complementary foods should initially be offered while gradually increasing variety in both the type and texture of food. Protein and carbohydrate intake should increase with the infant's age while preference should be given to foods rich in micronutrients. It should be observed that certain foods, such as fresh cow's milk and egg white, because of their allergenic properties, as well as fat-free and high-fibre foods, excessive fruit juice and low nutrient value drinks such as tea are not recommended. Timely introduction of appropriate complementary foods is vital for the immediate and long-term health of the infant and caregivers should be accordingly advised on feeding at this age.     

Does breast feeding protect from atopic diseases?

It is well established that food antigens can pass from mothers to infants via the breast milk. Bovine-beta-lactoglobulin has been detected in several breast milk samples from mothers with regular intake of cow's milk. Healthy breastfed infants can produce IgG antibodies against cow's milk protein and in infants at risk for atopic disease specific IgE antibodies were found before cow's milk based infant formula was introduced into the diet. However, several clinical studies in infants at risk for atopic disease indicate that exclusive breastfeeding decreases the incidence of atopic disease. The protective effect of breastfeeding is only relative and it is uncertain, how long protection lasts. Sensitization to food antigens may occur already in utero, because infants whose mothers avoid common allergenic foods during the whole pregnancy and then during the lactation period have a lower incidence of atopic eczema than infants whose mothers are on an unrestricted diet. Avoidance of common allergenic foods only during the last trimester of pregnancy had no effect, because the fetus is capable of forming IgE immune response.     

Plasma lipids and apolipoproteins in breastfed and formula-fed Swedish infants

This study was carried out to compare plasma lipid pattern in breastfed and formula-fed infants and the effects of exchanging breast milk for formula and of introducing weaning foods. Healthy infants, exclusively breastfed at least until 3 mo, were at this age randomly assigned to infant formulas with similar fat composition. Formula was gradually introduced when breastfeeding was discontinued. One group continued to breastfeed beyond 6 mo of age. All infants received the same weaning foods and were studied between 3 and 12 mo of age. Decreased plasma concentrations of total and low-density lipoprotein cholesterol (TC, LDL-C), apolipoprotein B (apo B) and A1 (p < 0.001), and of high-density lipoprotein cholesterol (p < 0.05) were found when breast milk was exchanged for formula before 6 mo. At this age plasma TC, LDL-C and apo B were lower in formula-fed than in breastfed infants (p < 0.001). These plasma lipids then increased (p < 0.01) when the intake of formula decreased and that of weaning foods increased. However, plasma TC and/or LDL-C remained lower at 12 mo in formula-fed than in breastfed infants (p < 0.05). Our results indicate that the plasma lipid profile of infants is highly responsive to the dietary nutrient intake, as indicated by the decrease in plasma lipids and apolipoproteins when breast milk was exchanged for formula and by the increase in these concentrations when the intake of weaning foods gradually increased.     

Infant feeding in urban south Indian families

A longitudinal study of feeding practices of South Indian infants 6-22 weeks of age revealed no differences between poor and middle class families. Even among the poor, artificial feeding was initiated in early infancy. The proportion of exclusively breastfed infants dropped from 82% at 6 weeks of age to 58% at 14 weeks and to 36% at 22 weeks. At 22 weeks of age, 16% of the 271 infants studied had been completely weaned from the breast. 58% of the bottle-fed infants were initially given diluted cow's milk while 28% received diluted commercial milk substitute. By the age of 22 weeks, 70% of the bottle-fed infants were receiving either full-strength cow's milk or formula. Commercial weaning foods were preferred up to the 18th week; after that point, rice and rice products were provided. At each age interval analyzed, the mean caloric intake from artificial food was less than half the daily caloric requirement. There was no significant difference between poor and middle class families in terms of the duration of breastfeeding or mean caloric intake from artificial feeds. At 22 weeks, 50% of poor infants and 71% of middle-class infants were receiving food supplements. 72% of infants who had been completely weaned by 22 weeks were from middle class families and 28% were from poor families. These findings confirm earlier observations that the urban poor in India are abandoning long-term breastfeeding and using up to 10% of family income on commercial infant food. Educational campaigns to promote prolonged breastfeeding and restricted use of artificial substitutes should be an important part of child health efforts in India.     

Breastfeeding practices of Cameroonian mothers determined by dietary recall since birth and the dose-to-the-mother deuterium-oxide turnover technique

Exclusive breastfeeding during the first 6 months of infant's life is a public health recommendation and important factor for the promotion of optimal growth, health and behavioural development of each child. The accuracy of the mothers' self-reported past infant-feeding events was examined and compared with the isotopic dilution technique. Breastfeeding practices were assessed in a sample of 44 Cameroonian mother-infant pairs using dietary recall since birth. Intakes of breast milk and non-breast milk water were measured in the same sample using the dose-to-the-mother deuterium-oxide turnover technique and compared with questionnaire. Results showed that mothers' self-reported behaviour overestimates the exclusive breastfeeding rate. Seventy-five per cent of the mothers who claimed to be exclusively breastfeeding were found to be predominantly or partially breastfeeding by the dose-to-the-mother deuterium-oxide turnover technique. Only 11% of the infants were exclusively breastfed, and the breast milk output was not significantly affected (P ≤ 0.05) by the mother's body composition. Mean intakes of breast milk and non-breast milk water were 701 mL day(-1) and 268 mL day(-1), respectively. Introduction of non-breast milk foods is associated with a reduction in the level of breast milk intake, but the difference in breast milk intake was not significant between exclusively and predominantly breastfed infants. In conclusion, the dose-to-the-mother deuterium-oxide turnover technique can be applied to validate the mother's reports of infant-feeding practices, but non-breast milk water intake by breastfeeding category still needs to be normalized.     

Fat intake and metabolism in Swedish and Italian infants

The purpose of the study was to compare fat intake and metabolism between two infant populations from Sweden and Italy given breast milk or similar infant formulas, but different weaning foods. Nutrient intake and fat metabolism were studied prospectively from 3-12 mo in 68 Swedish and 46 Italian healthy infants, breastfed or given similar infant formulas in combination with Swedish or Mediterranean weaning foods. Although nutrient intake and fat metabolism were similar at 6 mo, fat intake was lower at 12 mo in the Italian than in the Swedish formula group (p < 0.001). At 6 and 12 mo, higher dietary ratios of monounsaturated to saturated fatty acids (p < 0.01 and p < 0.001, respectively), and monounsaturated to polyunsaturated fatty acids (p < 0.05, p < 0.001) were found in the Italian than in the Swedish formula group. Total cholesterol and apolipoprotein B were lower at 6 mo (p < 0.01) in Italian breastfed infants than in Swedish ones. Lower concentrations at 6 and 12 mo of total cholesterol (p < 0.05, p < 0.05, respectively), apolipoprotein B (p < 0.05, p < 0.01) and triglycerides (p < 0.001, p < 0.01), and of apolipoprotein A1 (p < 0.01) at 12 mo, were found in the Italian formula group than in the Swedish one. In conclusion, plasma total cholesterol, apolipoprotein B and triglycerides were found to be lower in Italian infants than in Swedish infants during the second half of infancy. These findings may partly result from differences in fat compositions between Swedish and Mediterranean weaning diets and in total fat intake in late infancy. Differences in duration of breastfeeding and possibly in breast milk composition may also have influenced our results.     

Long-chain polyunsaturated fatty acids in human milk and brain growth during early infancy

Long-chain polyunsaturated fatty acids are essential for growth and development, and their crucial role in the development of the central nervous system and in retinal function has been the subject of many studies. As the balance between n-6 and n-3 fatty acids has to be optimal, their concentrations in the milk given to infants who are exclusively breastfed is of major importance. In this study, the composition of fatty acids in mothers' milk and the growth rate of the infant brain were analysed. Nineteen mother-term infant pairs from Stockholm, Sweden, were studied from birth to 1 mo and 3 mo of age, during which time the infants were breastfed exclusively. The dietary intake of the mothers was calculated and found to concur with the recommended daily dietary allowances of Swedish lactating women as regards energy, protein, fat and carbohydrates. The amounts of linoleic acid and alpha-linolenic acid in the diet were similar to those reported for European and North American women. The ratio between arachidonic acid (AA) and docosahexaenoic acid (DHA) in the milk from Swedish mothers is approximately the same as in the brain of infants, and was found to be positively correlated with the rate of gain of the occipito-frontal head circumference and of the calculated brain weight at 1 mo (p < 0.01) and 3 mo (p < 0.01) of age, respectively. However, further studies are needed to establish the exact requirements of AA and DHA for optimal growth and development during early infancy in exclusively breastfed infants.