Iron status at 12 months of age -- effects of body size, growth and diet in a population with high birth weight

Iron supplementation is positively associated with increased serum ferritin levels in 9-month-old Danish infants

Fe deficiency is still common in infancy, even in affluent societies, and has prompted Fe fortification of food products and use of Fe supplements in many populations. In the present study, we tested the hypothesis that Fe status among 9-month-old infants following the Danish Fe supplementation recommendation (>400 ml Fe-fortified formula or 8 mg Fe/d) is associated with more favourable levels of Fe status indicators compared to those not following the recommendation. A random sample of 9-month-old infants living in Copenhagen was established and 312 healthy term infants were examined at 9·1 (sd0·3) months of age. Blood samples were available from 278 infants. Overall, twenty infants (7·8 %) had Fe deficiency (serum ferritin < 12 μg/l) and < 1 % had Fe deficiency anaemia (serum ferritin < 12 μg/l and Hb < 100 g/l). Serum ferritin was positively associated with birth weight (P < 0·001), intake of fortified formula and follow-on formula (P = 0·001), and female sex (P < 0·001). Cow's milk intake and length of exclusive breast-feeding were negatively associated with Hb levels (P = 0·013 andP < 0·001). Serum ferritin levels were significantly higher (P < 0·0001) and transferrin receptor (TfR) was significantly lower (P = 0·003) among infants (n188) meeting the Fe supplementation recommendation compared to those (n67) not meeting the recommendation. No significant difference between these two groups was found for Hb. In conclusion, this study confirmed that Fe status of infants following the Danish Fe supplementation recommendation was significantly associated with increased serum ferritin and decreased levels of TfR indicating more favourable Fe status, compared to infants not following the recommendation.

Consumption of cow's milk as a cause of iron deficiency in infants and toddlers

Consumption of cow's milk (CM) by infants and toddlers has adverse effects on their iron stores, a finding that has been well documented in many localities. Several mechanisms have been identified that may contribute to iron deficiency in this young population group. The most important of these is probably the low iron content of CM, which makes it difficult for infants to obtain the amounts of iron needed for growth. A second mechanism is the occult intestinal blood loss associated with CM consumption during infancy, a condition that affects about 40% of otherwise healthy infants. Loss of iron in the form of blood diminishes with age and ceases after the age of 1 year. A third mechanism is the inhibition of non-heme iron absorption by calcium and casein, both of which are present in high amounts in CM. Fortification of CM with iron, as practiced in some countries, can protect infants and toddlers against CM's negative effects on iron status. Consumption of CM produces a high renal solute load, which leads to a higher urine solute concentration than consumption of breast milk or formula, thereby narrowing the margin of safety during dehydrating events, such as diarrhea. The high protein intake from CM may also place infants at increased risk of obesity in later childhood. It is thus recommended that unmodified, unfortified CM not be fed to infants and that it be fed to toddlers in modest amounts only.

Is cow's milk harmful to a child's health?

Discussions and debates have recently emerged on the potential positive and negative effects of cow's milk in the paediatric community, also under the pressure of public opinion. The negative effects of cow's-milk consumption seem to be limited to iron status up to 9 to 12 months; then no negative effects are observed, provided that cow's milk, up to a maximum daily intake of 500 mL, is adequately complemented with iron-enriched foods. Lactose intolerance can be easily managed and up to 250 mL/day of milk can be consumed. Allergy to cow's-milk proteins is usually transient. Atopic children may independently be at risk for poor growth, and the contribution of dairy nutrients to their diet should be considered. The connection of cow's milk to autistic spectrum disorders is lacking, and even a cause-effect relation with type 1 diabetes mellitus has not been established because many factors may concur. Although it is true that cow's milk stimulates insulin-like growth factor-1 and may affect linear growth, association with chronic degenerative, noncommunicable diseases has not been established. Finally, fat-reduced milk, if needed, should be considered after 24 to 36 months. Cow's milk represents a major source of high nutritional quality protein as well as of calcium. Moreover, it has growth-promoting effects independent of specific compounds. Its protein and fat composition, together with the micronutrient content, is suggestive of a functional food, whose positive effects are emphasised by regular consumption, particularly under conditions of diets poor in some limiting nutrients, although in industrialised countries cow's milk's optimal daily intake should be around 500 mL, adequately complemented with other relevant nutrients.

Nutrition and Iron Status of 1-Year Olds following a Revision in Infant Dietary Recommendations

A previous study showed low iron status in 12-month-old Icelandic infants associated most strongly with cow's milk intake and growth. Infant dietary recommendations were revised in 2003. This study investigated nutrition and iron status in a new infant cohort. Subjects/Methods. Randomly selected infants were prospectively investigated for diet, anthropometry, and iron status (n = 110–141). Results. Breastfeeding initiation rate was 98%; 38% of 5-month olds were exclusively and 20% of 12-month olds partially breastfed. Formula was given to 21% of 6-month olds and 64% of 12-month olds, but cow's milk to 2.5% and 54.4% of 6- and 12-month olds, respectively. Iron depletion (serum ferritin < 12 μg/L) affected 5.8%, 1.4% were also iron deficient (MCV < 74 fl), and none were anemic (Hb < 105 g/l). Iron status associated negatively with growth and breastfeeding duration and positively with meat and formula intake at 9–12 months, but not with cow's milk. Conclusion. Improved iron status might be explained by a shift from cow's milk to formula in the diet of Icelandic 6–12-month olds. Dietary changes altered associations between foods and iron status.

Food-based strategies improve iron status in toddlers: a randomized controlled trial12

BACKGROUND

Nonanemic iron deficiency is common in toddlers in developed countries. Food-based strategies are safe methods to control and prevent mild micronutrient deficiencies.

OBJECTIVE

Our objective was to determine the efficacy of an increased intake of red meat, or the consumption of iron-fortified milk, in improvement of iron status in toddlers at a population level.

DESIGN

In this 20-wk randomized placebo-controlled trial, 225 healthy nonanemic 12-20-mo-old children were assigned to 1 of 3 groups: red meat (toddlers encouraged to consume approximately 2.6 mg iron from red meat dishes daily), fortified milk [toddlers' regular milk replaced with iron-fortified (1.5 mg iron/100 g prepared milk) cow milk], or control [toddlers' regular milk replaced with nonfortified (0.01 mg iron/100 g prepared milk) cow milk]. Blood samples were collected at baseline and at 20 wk for hemoglobin, serum ferritin, serum transferrin receptor, and C-reactive protein. The prevalence of suboptimal iron status (ie, depleted iron stores, iron-deficient erythropoiesis, and iron deficiency anemia) was determined, and body iron was calculated.

RESULTS

No intervention effects were shown on the prevalence of suboptimal iron status. Serum ferritin increased by 44% (95% CI: 14%, 82%; P = 0.002) in the fortified milk group, did not change (+10%) in the red meat group (95% CI: -7%, 30%; P = 0.241), and tended to decrease (-14%) in the control group (95% CI: -27%, 1%; P = 0.063). By 20 wk, in comparison with the control group, serum ferritin and body iron were significantly higher in the fortified milk group (both P < 0.001), and serum ferritin was significantly higher in the red meat group (P = 0.033).

CONCLUSIONS

Consumption of iron-fortified milk can increase iron stores in healthy nonanemic toddlers, whereas increased intakes of red meat can prevent their decline. This trial was registered at actr.org.au as ACTRN12605000487617.

Linear and ponderal growth trajectories in well-nourished, iron-sufficient infants are unimpaired by iron supplementation

Iron deficiency remains the most common nutritional deficiency worldwide and supplementation is recommended during periods of high risk, including infancy. However, questions have been raised about possible adverse effects of iron on growth in iron-sufficient (IS) infants and the advisability of across-the-board iron supplementation. This study examined whether short- or long-term growth was impaired in IS infants who received iron supplementation. From a longitudinal study of healthy, breast-fed, low- to middle-income Chilean infants randomly assigned to iron supplementation or usual nutrition at 6 or 12 mo, we retrospectively identified infants meeting criteria for iron sufficiency at the time of random assignment (n = 273). Using multilevel analysis, ponderal and linear growth were modeled before, during, and after iron supplementation up to 10 y in 3 comparisons: 1) iron supplementation compared with usual nutrition from 6 to 12 mo; 2) iron supplementation compared with usual nutrition from 12 to 18 mo; and 3) 15 mg/d of iron as drops compared with iron-fortified formula (12 mg/L). Growth trajectories did not differ during or after supplementation indicating no adverse effect of iron in any comparison. These results suggest that, at least in some environments, iron does not impair growth in IS infants.

Adherence to food-based dietary guidelines and evaluation of nutrient intake in 7-year-old children

OBJECTIVE

To evaluate the diet of 7-year-old children by comparison with food-based dietary guidelines (FBDG) and reference values for nutrient intake.

DESIGN

Food and nutrient intake was assessed by 3 d weighed dietary records of 7-year-olds in six randomly chosen schools in Reykjavik, Iceland. Height and weight were measured. The diet of 165 children (62 % of sample) was evaluated by the Icelandic FBDG and the Nordic reference values (NRV) for nutrient intake.

SETTING

Six randomly chosen schools in Reykjavik, Iceland.

RESULTS

The FBDG on fruits and vegetables was reached by less than 20 % of the children. A total of 52 % reached the FBDG to eat fish twice a week and 41 % to use vitamin D supplement. The FBDG on dairy was reached by 66 % of the children. Mean intake of SFA gave 13.9 % of the total energy intake (E%), which is higher than the NRV, 9.3E% of MUFA and 3.8E% of PUFA, both lower than the NRV (for all differences P < 0.001). Added sugar gave 12.1E%, which exceeds the upper level (P < 0.001). Fibre intake was 2.1 g/MJ and lower than the NRV (P < 0.001). Mean intake of micronutrients was above the recommended intake (RI), except for iodine, 109.0 microg/d, and vitamin D, 6.1 microg/d, which was lower than the RI (P = 0.006 and P < 0.001, respectively).

CONCLUSIONS

Fruit, vegetable, fish and dairy, as well as vitamin D supplement, need to be increased in the diet of 7-year-old children to reach the FBDG and the reference values for nutrient intake. Dietary changes to increase the quality of fat and carbohydrate are needed as well.

Excessive Cow's Milk Consumption and Iron Deficiency in Toddlers

Elimination of iron deficiency and iron deficiency anemia in children is a crucial public health concern because these conditions have been linked to cognitive and behavioral deficits. In the infant age group, great strides have been made to reduce iron deficiency and iron deficiency anemia significantly. However, similar progress has not yet been made with toddlers. Cow's milk consumption has long been associated with iron deficiency and iron deficiency anemia in children. Because cow's milk is a staple in the diet of most toddlers, they are at particular risk for these conditions. Two unusual presentations of anemia in toddlers caused by excessive cow's milk consumption are described: one in a child with congestive heart failure, the other in a child with profound eosinophilia. The role of cow's milk in iron deficiency and iron deficiency anemia is also examined.

Unexpectedly high early prevalence of anaemia in 6-month-old breast-fed infants in rural Bangladesh

Objective

To determine the prevalence of anaemia and maternal and infant factors associated with Hb values in infants at 6 months of age in rural Bangladesh.

Design

Infants (born to mothers supplemented with Fe–folic acid from mid-pregnancy) were visited at birth and 6 months of age. Mothers’ anthropometric status, and infants’ birth weight, gestational age at birth, weight and Hb concentration at 6 months were measured. Household socio-economic and demographic data, infant feeding practices and health status were collected using a pre-tested structured questionnaire.

Setting

Rural Bangladesh.

Subjects

Four hundred and two infants.

Results

For the total cohort (n 402), the range of anaemia prevalence values was from 30·6 % using a cut-off value of Hb < 95 g/l to 71·9 % using a value of Hb < 110 g/l. Birth weight and month of birth were the only factors positively associated with infant Hb in a linear regression model (P = 0·008 and 0·011, respectively).

Conclusions

There was an unexpectedly high prevalence of anaemia in infants at 6 months of age, before the assumed period of vulnerability. Hb at this age tended to be higher in those with higher birth weight. We also found a season effect on Hb, as it tended to be higher as the study progressed. The high prevalence of anaemia at such an early age needs to be addressed to minimize the disease’s long-term consequences.

Prevalence and predictors of iron deficiency in fully breastfed infants at 6 mo of age: comparison of data from 6 studies

BACKGROUND

Iron deficiency (ID) can occur among exclusively breastfed infants before 6 mo of age.

OBJECTIVE

The objective was to determine which subgroups of fully breastfed infants are at highest risk of ID.

DESIGN

We assessed the prevalence of ID (ferritin < 12 mug/L) and iron deficiency anemia (IDA; ferritin < 12 mug/L and hemoglobin < 105 g/L) and risk factors associated with ID and IDA at 6 mo among 404 fully breastfed infants with a birth weight >2500 g from 6 studies in Ghana, Honduras, Mexico, and Sweden. Infants with an elevated C-reactive protein concentration (8%) were excluded.

RESULTS

The percentages of infants with ID were 6% in Sweden, 17% in Mexico, 13-25% in Honduras, and 12-37% in Ghana. The percentages with IDA were 2% in Sweden, 4% in Mexico, 5-11% in Honduras, and 8-16% in Ghana. With data pooled, the key predictors of ID (20%) were male sex [adjusted odds ratio (AOR): 4.6; 95% CI: 2.5, 8.5] and birth weight 2500-2999 g (AOR: 2.4; 95% CI: 1.4, 4.3). The predictors of IDA (8%) were male sex (AOR: 7.6; 95% CI: 2.5, 23.0), birth weight of 2500-2999 g (AOR: 3.4; 1.5, 7.5), and weight gain above the median since birth (AOR: 3.4; 95% CI: 1.3, 8.6). The combination of birth weight 2500-2999 g or male sex had a sensitivity of 91% for identifying ID and of 97% for identifying IDA.

CONCLUSIONS

Among fully breastfed infants with a birth weight >2500 g, IDA is uncommon before 6 mo, but male infants and those with a birth weight of 2500-2999 g are at higher risk of ID and IDA.

Complementary feeding: a commentary by the ESPGHAN Committee on Nutrition

This position paper on complementary feeding summarizes evidence for health effects of complementary foods. It focuses on healthy infants in Europe. After reviewing current knowledge and practices, we have formulated these conclusions: Exclusive or full breast-feeding for about 6 months is a desirable goal. Complementary feeding (ie, solid foods and liquids other than breast milk or infant formula and follow-on formula) should not be introduced before 17 weeks and not later than 26 weeks. There is no convincing scientific evidence that avoidance or delayed introduction of potentially allergenic foods, such as fish and eggs, reduces allergies, either in infants considered at increased risk for the development of allergy or in those not considered to be at increased risk. During the complementary feeding period, >90% of the iron requirements of a breast-fed infant must be met by complementary foods, which should provide sufficient bioavailable iron. Cow's milk is a poor source of iron and should not be used as the main drink before 12 months, although small volumes may be added to complementary foods. It is prudent to avoid both early (<4 months) and late (>or=7 months) introduction of gluten, and to introduce gluten gradually while the infant is still breast-fed, inasmuch as this may reduce the risk of celiac disease, type 1 diabetes mellitus, and wheat allergy. Infants and young children receiving a vegetarian diet should receive a sufficient amount ( approximately 500 mL) of breast milk or formula and dairy products. Infants and young children should not be fed a vegan diet.

Infant feeding in the second 6 months of life related to iron status: an observational study

OBJECTIVE

To investigate the relationship between iron status in infancy and type of milk and weaning solids consumed.

DESIGN

An observational cohort study.

SETTING

928 term infants from the Avon Longitudinal Study of Parents and Children in 1993-94.

METHODS

Haemoglobin and ferritin concentrations at 8 and 12 months were assessed in relation to type and quantity of milk intake at 8 months.

RESULTS

By WHO criteria, 22.7% of the infants were anaemic at 8 months and 18.1% at 12 months. More breast--than formula-fed infants were anaemic at 8 and 12 months. Cows' milk as the main drink was associated with increased anaemia at 12 months and low ferritin at 8 and 12 months. No association was found between any nutrients and haemoglobin concentrations. Protein and non-haem iron intakes were positively associated with ferritin concentrations and calcium intake negatively. This effect was more marked in infants being fed cows' milk. More than 25% of infants in the breast milk and cows' milk groups and 41% of infants having >6 breast feeds per day had iron intakes below the lower reference nutrient intake. Feeding cows' milk or formula above 600 ml or >6 breast feeds per day was associated with lower intakes of solids.

CONCLUSIONS

Both breast and cows' milk feeding were associated with higher levels of anaemia. Satisfactory iron intake from solids in later infancy is more likely if formula intake is <600 ml per day and breast feeds are limited to <6 feeds per day. Cows' milk should be strongly discouraged as a main drink before 12 months.

Fetal alcohol exposure, iron-deficiency anemia, and infant growth

OBJECTIVES

Our goals were to determine whether prenatal alcohol exposure is associated with an increased incidence of iron-deficiency anemia in infancy and to compare effects of fetal alcohol exposure and iron-deficiency anemia on infant growth. We also tested whether effects of fetal alcohol exposure on growth are mediated or moderated by iron-deficiency anemia.

METHODS

A total of 96 infants born to mothers from the Coloured (mixed ancestry) community in Cape Town, South Africa, were recruited prenatally; 42 mothers drank heavily during pregnancy, and 54 abstained or drank small amounts of alcohol. Growth was assessed at birth and 6.5 and 12 months, and iron-deficiency anemia was assessed at 6.5 or 12 months.

RESULTS

Infants whose mothers binge drank during pregnancy (> or = 4 drinks per occasion) were 3.6 times more likely to be diagnosed with iron-deficiency anemia at 12 months than were infants whose mothers did not binge drink. Prenatal alcohol exposure was associated with reduced weight at birth, 6.5 months, and 12 months and with shorter length at 6.5 and 12 months. Iron-deficiency anemia was related to reduced 12-month weight and head circumference and to slower growth velocity between 6 and 12 months. The effects of prenatal alcohol on weight were not mediated by iron-deficiency anemia; however, they were seen primarily in infants with iron-deficiency anemia.

CONCLUSIONS

The association of maternal binge drinking with an increased incidence of iron-deficiency anemia may reflect disruption of accumulation of fetal iron stores or postnatal deficiencies in iron uptake, absorption, or intake. Moreover, iron deficiency seems to exacerbate the prenatal alcohol effects on growth.

Session 4: Mineral metabolism and body composition Iron status of breast-fed infants

Fe deficiency is a common nutritional disorder during infancy, particularly in low-income countries. The Fe status of a breast-fed infant is strongly influenced by the body Fe content at birth, which is determined by factors that operate before birth (maternal Fe status before and during pregnancy; infant gestational age and birth weight) and at the time of delivery (the timing of umbilical cord clamping). Delaying the clamping of the umbilical cord for 2 min can increase body Fe content by approximately 33% (75 mg), and results in greater Fe stores at 6 months of age. After birth, male gender and a rapid rate of weight gain are associated with lower Fe status. During the first half of infancy dietary Fe requirements depend on Fe stores at birth. For an exclusively-breast-fed full-term normal-birth-weight infant with delayed umbilical cord clamping, whose mother had adequate Fe status during pregnancy, the Fe provided from stores and breast milk is sufficient for ≥6 months, but before this time higher-risk infants may become Fe deficient. Fe supplementation can be beneficial for high-risk infants, but can have adverse effects on growth and morbidity of Fe-replete infants. After 6 months most breast-fed infants will require complementary foods that are rich in Fe.

Predictors of serum ferritin and serum soluble transferrin receptor in newborns and their associations with iron status during the first 2 y of life

BACKGROUND

Adequate iron status at birth may prevent iron deficiency in early childhood.

OBJECTIVES

We aimed to identify predictors of serum ferritin (SF) and serum soluble transferrin receptor (sTfR) in healthy newborns and to relate these iron indexes to iron status in the first 2 y of life.

DESIGN

Using bivariate correlations and linear regression, we related various factors in pregnancy to SF (n=363) and sTfR (n=350) in healthy, term infants. Measurements of cord SF and sTfR were compared with those of SF and sTfR at 6, 12, and 24 mo. All 4 measurements were available for 191 and 169 infants for SF and sTfR, respectively.

RESULTS

Geometric mean (and 95% CI) cord SF and sTfR measurements were 159 (148, 171) microg/L and 7.3 (7.0, 7.6) mg/L, respectively. Cord SF correlated with sTfR (rho=-0.21, P<0.001). In regression analysis, cord SF correlated with smoking and the use of iron supplements during pregnancy (partial r=-0.12 and 0.16; P<0.05 for both). Cord sTfR was associated with first trimester BMI, gestational age, and male sex (partial r=0.30, 0.24, and 0.19, respectively; P<0.01 for all). Cord SF correlated with SF at 6, 12, and 24 mo (rho=0.45, 0.31, and 0.16 respectively; P<0.05 for all). At age 6 mo, 16 of 17 infants with SF <15 mug/L were boys.

CONCLUSIONS

Cessation of smoking and adequate iron prophylaxis during pregnancy may improve iron status in infancy. Cord SF is a predictor of iron status in the first 2 y of life. Boys are at particular risk of low iron status in early infancy.

Policy statement on iron deficiency in pre-school-aged children

AIM

We aimed to develop policy in relation to three areas: (i) the diagnosis of iron deficiency; (ii) maternal-infant issues and the prevention of iron deficiency; and (iii) the treatment of iron deficiency.

METHODS

Within each of these topic areas we completed a literature review and developed recommendations to help direct activities of the Royal Australasian College of Physicians, update paediatricians and guide clinical practice.

RESULTS

Iron deficiency can be defined using cut-off values for laboratory measures of iron status or, if an intercurrent infection is not present, by demonstrating a response to a therapeutic trial of iron. The appropriate measures of iron status vary depending upon the presence of intercurrent infection. Full-term babies are born with iron stores sufficient to meet their needs to age 4-6 months but premature infants are not. After age 6 months infants are dependent upon dietary iron from complementary foods even with continued breastfeeding. Infants <33 weeks gestation or <1800 g birthweight should receive iron from 4 weeks of age. In most settings recommended treatment of iron deficiency is with oral ferrous sulphate as a single or twice daily dose of between 3 and 6 mg/kg/day.

CONCLUSIONS

Iron deficiency is prevalent and an important determinant of child health. Precise and accurate diagnosis remains challenging. Iron supplementation is required for premature and low-birthweight infants. Oral iron salts remain the recommended treatment of choice in most instances.

Iron status at 1 and 6 years versus developmental scores at 6 years in a well-nourished affluent population

AIM

To examine the association between iron status at 1 and 6 years with development at 6 years.

METHODS

In a longitudinal study of children (n = 77), iron status was measured at 1 and 6 years and the Icelandic Developmental Inventory, which evaluates children's motor and verbal development, was filled in by mothers near the children's sixth birthday.

RESULTS

Children, iron-deficient at 1 year (n = 10), had lower fine motor development scores at 6 years than non-iron-deficient (n = 56) (46.7 +/- 4.1 vs. 49.3 +/- 2.0; p = 0.011). Fine motor scores were also lower in children with depleted iron stores at 1 year (n = 26) than non-iron-depleted children (n = 40) (48.0 +/- 3.3 vs. 49.5 +/- 1.8; p = 0.045). Multiple regression analyses, with iron status indices at 6 years, showed that mean corpuscular volume along with male gender predicted significantly positively for expression (adj. R(2)= 0.15; p = 0.018; n = 73), while regression analyses, including iron status at 1 and 6 years, showed that haemoglobin at 6 years was positively associated with gross motor (adj. R(2)= 0.05; p = 0.038; n = 63).

CONCLUSIONS

In an affluent society, iron deficiency and depleted iron stores at 1 year may contribute to worse fine motor developmental scores at 6 years, while low mean corpuscular volume and haemoglobin at 6 years might affect subsequent expression and gross motor scores negatively.

Iron status of inner-city African-American infants

The iron status of African-American infants continues to be subject to debate. We characterized the iron status of 198 9-month-old inner-city infants (94% fed iron-fortified formula) using a comprehensive panel of measures and assessing lead and inflammation markers. The proportion with iron deficiency was calculated based on three approaches (> or = 2 abnormal iron measures with or without anemia for MCV model--NHANES II, ferritin model--NHANES III, or Sweden/Honduras study) and a promising new measure-body iron, calculated from ferritin and transferrin receptor (TfR). There were no sex differences for any iron measure. Hb < 110 g/l was observed in 25%; Hb < or = 105 g/l in 10.1%. Free erythrocyte protoporphyrin (FEP) values were elevated without elevated lead concentrations or an inflammatory response: mean FEP = 86.6 microg/dl red blood cells [75.5 micromol/mol heme]; 52.3% were > 80 microg/dl (1.42 micromol/l), almost half of which were accompanied by a second abnormal iron measure. The estimated prevalence of iron deficiency was 14.4, 5.3, and 2.5% for the MCV model, ferritin model, and Sweden/Honduras cutoffs, respectively, and 4.1% for body iron < 0 mg/kg. Regulation of iron storage is immature at < 1 year of age, making estimates of iron deficiency that depend on ferritin, including body iron, suspect in this age period. Thus, the "true" prevalence of iron deficiency could not be established with confidence due to major differences in the results, depending on the guidelines used. Functional indicators of poor iron status in young infants are urgently needed.

Zinc protoporphyrin/heme in large-for-gestation newborns

BACKGROUND

Zinc protoporphyrin/heme (ZnPP/H) ratios are indicators of incomplete erythrocyte iron delivery. ZnPP/H is more sensitive than measures of iron stores, such as plasma ferritin, in identifying early pre-anemic iron-deficient erythropoiesis. Cord ZnPP/H ratios are elevated in conditions associated with fetal hypoxia, such as diabetes mellitus during pregnancy. In chronic fetal hypoxemia, erythrocyte and hemoglobin syntheses are accelerated and iron is incorporated into erythrocytes. Cord ZnPP/H ratios are correlated with fetal size after diabetic pregnancy. Because fetal size is a surrogate for diabetes control, it is unclear whether glycemic control in diabetes mellitus or fetal size was the major determinant of ZnPP/H ratios and disturbed erythrocyte iron delivery.

OBJECTIVE

Our goal was to examine whether ZnPP/H ratios were elevated or were associated with growth in large-for-gestation newborns born to mothers without the diagnosis of diabetes mellitus.

METHODS

In cord blood samples from large and appropriately grown healthy newborns, we measured ZnPP/H and indices of erythropoiesis and iron status. Analyses included simple linear regression, Fisher's exact, and unpaired t testing.

RESULTS

In the absence of diabetes mellitus, ZnPP/H in 25 large and 24 appropriately grown healthy newborns was similar, and the ratios were within the limits of previously reported normal cord ZnPP/H. Ratios were not correlated with plasma ferritin levels. In large newborns, but not appropriately grown newborns, ZnPP/H ratios were positively correlated with fetal growth (p < 0.03) and estimates of body hemoglobin (p <0.04).

CONCLUSIONS

Despite 33% greater body hemoglobin mass observed in healthy large, compared to appropriately grown newborns, mean ZnPP/H was normal. Iron incorporation into erythrocytes in large newborns appears adequate. Because the association of ZnPP/H with size and estimated body hemoglobin was observed only in large newborns, factors determining ZnPP/H may differ between large and appropriately grown newborns.

Iron deficiency in infancy: applying a physiologic framework for prediction

BACKGROUND

Infants aged 6-24 mo are at high risk of iron deficiency. Numerous studies worldwide have sought to identify predictors of iron deficiency in this age group.

OBJECTIVE

The objectives of the study were to apply a physiologic model to identify risk factors for iron deficiency and to consider those risk factors under different conditions of iron supplementation. We predicted that factors related to iron status at birth (lower gestational age and lower birth weight), postnatal needs for iron (more rapid growth), and bioavailable iron (more cow milk) would be major risk factors.

DESIGN

The physiologic framework was assessed in 1657 Chilean infants (aged 12 mo) with birth weights >or=3 kg who were randomly assigned at age 6 mo to high or low iron supplementation or no added iron. Based on venous blood, the analysis used mean corpuscular volume and concentrations of hemoglobin, free erythrocyte protoporphyrin, and ferritin. Logistic regression models were used to identify predictors of iron deficiency anemia and iron deficiency without anemia.

RESULTS

The prevalence of iron deficiency (>or=2 abnormal iron measures) was 34.9% at age 12 mo. Of 186 infants with hemoglobin concentrations <110 g/L, 158 (84.9%) were iron deficient. The only consistent (and the strongest) predictor of iron deficiency or iron deficiency anemia was lower 6-mo hemoglobin. Factors related to poorer iron status at birth (lower birth weight, shorter gestation though full-term, or both) were predictors in the no-added-iron and high-iron groups. Otherwise, predictors varied by iron supplementation.

CONCLUSION

Variations in predictors of iron deficiency or iron deficiency anemia according to iron supplementation suggest that direct comparisons across studies are tenuous at best without data on early iron status and certainty that specific conditions are comparable.

Duration of pregnancy in relation to seafood intake during early and mid pregnancy: prospective cohort

We examined the association between exposure to seafood intake during two periods of pregnancy on the one hand and risks of preterm delivery and postterm delivery on the other. In a prospective cohort of 8729 pregnant Danish women, we assessed frequency of fish meals during the first and second trimester of pregnancy by questionnaires completed around gestation weeks 16 and 30, respectively. When fish intake was based solely on intake reported for the early period of pregnancy, mean gestation length was shorter by 3.91 (95% CI: 2.24-5.58) days and odds of preterm delivery were increased 2.38 (1.23-4.61) times in those who never consumed fish (n = 308) vs. those who consumed both fish as main meal and fish in sandwiches at least once per week (n = 785). These measures were similar when fish intake was based solely on intake reported for mid-pregnancy. In the subgroup of women reporting same intake in the two trimesters, those who never consumed fish (n = 165) had 8.57 (5.46-11.7) days shorter mean gestation and 19.6 (2.32-165) times increased odds of preterm delivery, compared to high fish consumers (n = 127); odds of elective and postterm delivery were reduced by a factor 0.33 (0.11-1.02) and 0.34 (0.12-0.95), respectively, in zero fish consumers. All analyses were adjusted for potential confounding by factors such as maternal smoking, height, and prepregnant weight. We conclude that never consuming fish in the first two trimesters of pregnancy was an extremely strong risk factor for preterm delivery but was also associated with reduced risks of elective delivery and postterm delivery.

Associations of iron status with dietary and other factors in 6-year-old children

OBJECTIVE

To investigate the associations of iron status at 6 years of age with dietary and other factors.

DESIGN

In a cross-sectional study, children's dietary intakes (3-day weighed food record) were recorded, body size was measured and blood samples were taken near their sixth birthday.

SUBJECTS

A sample of 188 children, from two previous studies (cohorts 1 and 2), was contacted, and 139 (74%) agreed to participate.

RESULTS

Multiple regression analyses with dietary and other factors showed that meat and fish consumption, multivitamin/mineral supplement intake (both positively) and cow's milk product consumption (negatively) were associated with log serum ferritin (SF) (adjusted R (2)=0.125; P=0.028; n=129), and juices and residence (rural>urban) with haemoglobin (Hb) (adjusted R (2)=0.085; P=0.034; n=127). Of 21 multivitamin/mineral consumers, none had depleted iron stores compared to 21 iron-depleted of 108 non-consumers (P=0.024). Children living in rural areas (<10,000 inhabitants) (n=33) had higher mean corpuscular volume (MCV) (83.3+/-2.3 fl) than those living in urban areas (>10,000 inhabitants) (82.1+/-3.2 fl; n=103) (P=0.048). Multiple regression analyses with dietary and other factors and growth showed in cohort 1 that residence (rural>urban), weight gain 0-1years (negatively), and meat and fish intake (positively) were associated with Hb (adjusted R (2)=0.323; P=0.030; n=51), meat and fish (positively) with both log SF (adjusted R (2)=0.069; P=0.035; n=52) and MCV (adjusted R (2)=0.064; P=0.035; n=52), and in cohort 2 cow's milk product consumption (negatively) was associated with log SF (adjusted R (2)=0.119; P=0.017; n=41) and residence (rural>urban) with MCV (adjusted R (2)=0.102; P=0.025; n=41).

CONCLUSIONS

Consumption of meat and fish and possibly also juices, as well as multivitamin/mineral intake might affect iron status in 6-year-old children positively, whereas cow's milk product consumption might affect iron status negatively. Slower growth in the first year of life and rural residence are positively related to iron status of 6-year-olds.

Feeding Patterns and Weight Among First Nations Children

Purpose: Little information is available on the growth and feeding patterns of First Nations children. Our goal was to assess the anthropometric status, feeding practices, and dietary intake of children born in 1994 or 1995 (n=102) and living in Walpole Island First Nation.

Methods: Information on demographic characteristics and infant feeding practices was obtained through parent interviews conducted between 1994 and 1999. Parents also completed a 24-hour dietary recall for their children when they were 48 months old. Head circumference was measured at three and 18 months, and weight and length/height at three, 18, 33, and 48 months.

Results: Most infants (75%) were breastfed at birth; however, by the time infants were three months old, 39.7% of the mothers had stopped breastfeeding. Over half (57.1%) of the infants were fed solids before age three months, 11.6% were given whole milk before age nine months, and 59.4% had low fat milk before age two years. Body mass index (kg/m2) (BMI) was above the 85th percentile for 27.8% at the 48-month interview, and was associated with a maternal BMI above 25 (OR=7.8, CI=1.1-41.9).

Conclusions: Mothers need to be encouraged to follow current infant feeding recommendations. Strategies should be developed to reduce the prevalence of overweight among adults and children in First Nations communities.

Risk of infant anemia is associated with exclusive breast-feeding and maternal anemia in a Mexican cohort

The WHO recommends exclusive breast-feeding (EBF) for the first 6 mo of life to decrease the burden of infectious disease. However, some are concerned about the effect of EBF >6 mo on iron status of children in developing countries in which anemia is prevalent. This study examines the risk of anemia in relation to the duration of EBF and maternal anemia in a birth cohort studied between March 1998 and April 2003. All infant birth weights were >or=2.2 kg. All mothers received home-based peer counseling to promote EBF. Infant feeding data were collected weekly. Nurses measured hemoglobin (Hb) values every 3 mo. Hb was measured in 183 infants at 9 mo of age. Anemia at 9 mo was defined as a Hb value <100 g/L. EBF was defined by WHO criteria and ranged in duration from 0 to 31 wk. At 9 mo, Hb (mean +/- SEM) was 114 +/- 0.9 g/L; 23 children (12.5%) had Hb levels <100 g/L. EBF >6 mo, but not EBF 4-6 mo, was associated with increased risk of infant anemia compared with EBF <4 mo (odds ratio=18.4, 95% CI=1.9, 174.0). Maternal anemia was independently (P=0.03) associated with a 3-fold increased risk of infant anemia. These associations were not explained by confounding with other maternal or infant factors. By linear regression, a lower infant Hb at 9 mo was associated with increased EBF duration among mothers who had a history of anemia (beta=-0.07, P=0.003), but not among mothers with no history of anemia. Infants who are exclusively breast-fed for >6 mo in developing countries may be at increased risk of anemia, especially among mothers with a poor iron status; greater attention to this issue is warranted.

Iron status in 6-y-old children: associations with growth and earlier iron status

OBJECTIVE

To investigate the iron status of 6-y-old children and its association with growth and earlier iron status.

DESIGN

In a cross-sectional study, children's body size measurements were recorded and blood samples taken near their sixth birthday.

SUBJECTS

A sample of 188 children, randomly selected in two previous studies, was contacted, and 139(74%) agreed to participate.

RESULTS

No children had iron deficiency anaemia, one was iron-deficient (serum ferritin (SF) <15 microg/l and mean corpuscular volume (MCV) <76 fl but 16% had depleted iron stores (SF<15 microg/l). Iron status indices were generally higher than at 1 and 2 y, but correlation was seen between iron status indices at 6 y and earlier values. Haemoglobin concentration at 6 y was negatively associated with length gain from birth to 1 y (B+/-s.e.=-1.269+/-0.452; P=0.007; adj. R2=0.119) (n=52), and proportional weight gain from birth to 1 y was higher among children with SF<15 microg/l at 6 y (295+/-33%; n=10) than those with SF> or =15 microg/l (258+/-31%; n=49) (P=0.001). MCV at 2 y predicted weight gain from 2 to 6 y (B+/-s.e.=1.721+/-0.581; P=0.005; adj. R2=0.153) (n=44); also, children with SF<15 microg/l at 6 y (n=9) gained 7.8+/-1.2 kg from 2 to 6 y, while children with SF> or =15 microg/l (n=35) gained 9.6+/-2.8 kg (P=0.007), furthermore a difference was seen in proportional weight gain from 2 to 6 y between children with depleted iron stores at 2 y and not, or 156+/-13 vs 169+/-18% (P=0.038).

CONCLUSION

The results suggest that low iron status at 1 and 2 y might lead to slower growth up to 6 y of age. Low iron status at 1 and 2 y and/or slower growth from 1 and 2 y up to 6 y might contribute to worse iron status at 6 y, while faster growth in early childhood is related to lower iron status.

Maternal body mass index, duration of exclusive breastfeeding and children's developmental status at the age of 6 years

OBJECTIVE

To investigate whether the duration of exclusive breastfeeding and maternal body mass index (BMI) are associated with children's developmental status at the time of beginning elementary school.

DESIGN AND SUBJECTS

The subjects in the sample came from a longitudinal study on infant nutrition in Iceland. Food records were made once a month from birth to the age of 12 months, from which duration of exclusive breastfeeding could be determined. Mothers filled in The Icelandic developmental inventory for evaluation of motor and verbal development close to their children's sixth birthday (n = 85). Maternal self-reported weight and height was recorded. Information on socioeconomic factors was gathered by a questionnaire.

RESULTS

Duration of exclusive breastfeeding, in months, was positively related to children's motor component (B = 0.5+/-0.5, P = 0.054) and to the total developmental index (B = 1.0+/-0.5, P = 0.044) at 6 y, adjusting for gender and socioeconomic factors (maternal and paternal education, and family income). Children's learning score was negatively related to maternal BMI (B = -0.5+/-0.2, P=0.047). An inverse association also appeared between maternal BMI and two out of the three developmental composite scores, that is, verbal component and the total developmental index (B = -0.6+/-0.3, P=0.049) and (B = -0.4+/-0.2, P=0.057), respectively. In multiple regression the developmental indexes were most strongly independently associated with maternal BMI (negatively) and infants' birth weight (positively).

CONCLUSION

Maternal BMI and duration of breastfeeding were associated with verbal and motor development of 6-y-old children, independent of socioeconomic factors. Birth weight was also an independent determinant for developmental scores.

Iron status in 2-year-old Icelandic children and associations with dietary intake and growth

OBJECTIVE

To investigate the effects of food and nutrient intake at 2 y and growth from birth on iron status at 2 y in a population with high birth weight.

DESIGN

In a cross-sectional study, children's food consumption and body size measurements were recorded and blood samples taken. Weighed 3-day food records were used to analyse food and nutrient intake.

SETTING

Children were recruited from across Iceland from the Icelandic National Registry by the University of Iceland, Computing Services. The children in the sample were born over a 1-y period.

SUBJECTS

Parents of randomly selected 2-year-old children (n=130) were contacted, and 72% (n=94) participated. Blood samples were analysed in 76% (n=71) of participating children.

RESULTS

In total, 9% of the children were iron-deficient (serum ferritin (SF)<12 microg/l and mean corpuscular volume (MCV) <74 fl) and 1.4% were also anaemic (Hb<105 g/l), while 27% of children were iron-depleted (SF<12 microg/l). Iron status indices were negatively associated with cow's milk consumption. Half of children consuming>500 g cow's milk/day (n=10) were iron-deficient, while one child in 58 consuming<500 g cow's milk/day had iron deficiency (P<0.001). In multiple regression analyses, also biscuits and crackers consumption was positively associated with MCV. Weight gain from birth to 2 y was negatively associated with SF (adjusted R(2)=0.15; P=0.002; n=58). Iron-depleted children were heavier than children not iron-depleted (14.7+/-1.3 vs 13.8+/-1.7 kg; P=0.043), had higher BMI (17.7+/-1.5 vs 16.7+/-1.4 kg/m(2); P=0.028) and gained more weight from birth (11.2+/-1.3 vs. 10.0+/-1.6 kg; P=0.011).

CONCLUSIONS

The results suggest that cow's milk consumption above 500 g/day should be avoided at the age of 2 y for better iron status. Iron depletion at 2 y is associated with faster growth from birth.

Dietary iron intake is positively associated with hemoglobin concentration during infancy but not during the second year of life

Iron status during infancy and early childhood reflects highly dynamic processes, which are affected by both internal and external factors. The regulation of iron metabolism seems to be subjected to developmental changes during infancy, although the exact nature of these changes and their implications are not fully understood. We wanted to explore the association between dietary iron intake and indicators of iron status, and to assess temporal changes in these variables. This was done by secondary analysis of data from a recently conducted dietary intervention trial in which healthy, term, well-nourished infants were randomly assigned to consume iron-fortified infant cereals with regular or low phytate content, or iron-fortified infant formula. Dietary iron intake from 6 to 8 mo and from 9 to 11 mo was associated with hemoglobin (Hb) concentration at 9 mo (r = 0.27, P < 0.001) and 12 mo (r = 0.21, P = 0.001), respectively, but iron intake from 12 to 18 mo was not associated with Hb at 18 mo. In contrast, iron intake from 6 to 11 mo was not associated with serum ferritin (S-Ft) at 9 or 12 mo, whereas iron intake from 12 to 17 mo was positively associated with S-Ft at 18 mo (r = 0.14, P = 0.032). These shifts in associations between dietary iron intake, and Hb and S-Ft, respectively, may be due to developmental changes in the channeling of dietary iron to erythropoiesis relative to storage, in the absence of iron deficiency anemia. These observations should be taken into consideration when evaluating iron nutritional status during infancy and early childhood.

Iron deficiency and iron deficiency anaemia during infancy and childhood

The present definition of iron deficiency and iron deficiency anaemia is under debate. Our present figures for the prevalence of iron deficiency in infants and toddlers are thus disputed.

CONCLUSION

Better understanding of the regulation of iron metabolism and requirement during the critical early period of growth and development is needed for relevant control of iron deficiency anaemia.

Relationship between growth and feeding in infancy and body mass index at the age of 6 years

OBJECTIVE

To assess the relationship between size and growth measurements in infancy to body mass index (BMI) at 6 y.

DESIGN

A longitudinal observation study on randomly chosen infants' growth and consumption in infancy. Follow-up until the age of 6 y.

SUBJECTS

A total of 90 children who were born healthy and full-term.

MEASUREMENTS

Weight and height were measured at maternity wards and healthcare centers in Iceland throughout infancy and at 6 y. Food records were made every month during infancy. At 2, 4, 6, 9 and 12 months, food was weighed to calculate food and nutrient intake.

RESULTS

Weight gain from birth to 12 months as a ratio of birth weight was positively related to BMI at the age of 6 y in both genders (B=2.9+/-1.0, P=0.008, and B=2.0+/-0.9, P=0.032 for boys and girls, respectively). Boys in the highest quartile of protein intake (E%) at the age of 9-12 months had significantly higher BMI (17.8+/-2.4 kg/m(2)) at 6 y than the lowest (15.6+/-1.0 kg/m(2), P=0.039) and the second lowest (15.3+/-0.8 kg/m(2), P=0.01) quartile. Energy intake was not different between groups. Together, weight gain at 0-12 months and protein intake at 9-12 months explained 50% of the variance in BMI among 6-y-old boys.

CONCLUSION

Rapid growth during the first year of life is associated with increased BMI at the age of 6 y in both genders. In boys, high intake of protein in infancy could also contribute to childhood obesity.