Iron and copper in human milk

A cohort study of haemoglobin and zinc protoporphyrin levels in term Zambian infants: effects of iron stores at birth, complementary food and placental malaria

OBJECTIVE

To examine zinc-protoporphyrin (ZPP) and haemoglobin levels, and to determine predictors of iron deficiency anaemia (IDA) in Zambian infants.

SUBJECTS AND METHODS

Ninety-one women and their normal birth weight (NBW) infants were followed bi-monthly during the first 6 months of life, and iron status, food intake, malaria parasitaemia and growth were monitored. At 4 months, the infants were divided into two groups, and the data were analysed according to whether or not they were exclusively breastfed.

RESULTS

Almost two-third of infants were born with low iron stores as defined by ZPP levels, and this proportion increased with age. Over 50% had developed IDA by 6 months. Exclusive breastfeeding at 4 months could be a protective factor for IDA (odds ratio (OR): 0.2; 95% confidence interval (CI): 0.0-1.1). Exclusively breastfed infants had higher haemoglobin values at 4 and 6 months (mean difference 0.6; 95% CI: 0.1-1.2 g/dl and mean difference 0.9; 95% CI: 0.2-1.7 g/dl, respectively), compared with infants with early complementary feeding. In univariate analysis, past or chronic placental malaria appeared to be a predictor of IDA at 4 and 6 months, but the significance was lost in multivariate analysis.

CONCLUSIONS

Zambian NBW infants are born with low iron stores and have a high risk to develop IDA in the first 6 months of life. Continuation of exclusive breastfeeding after 4 months is associated with a reduction of anaemia. The effect of placental malaria infection on increased risk of infant IDA could not be proven.

Daily fluctuations and distribution of xenobiotics, nutritional and biogenic elements in human milk in Southern Poland

Cadmium, lead, zinc, copper, calcium and magnesium levels were determined (with voltametric and AAS methods) in mature breast milk (obtained 12 weeks after birth) from women living in the Malopolska District, near Krakow, Poland. Milk was sampled from lactating women during a 14-day period three times a day: at 9:00 am, 3:00 pm, and 9:00 pm. A total of 210 milk samples was collected. In general we noticed the presence of differences both in the levels of Cd and Pb between milk samples taken from different women and statistically significant daily changes of Cd level in two cases and Pb level in three cases. We found daily fluctuations of trace elements levels in milk samples taken from two women in case of Zn, and from one woman in case of Cu. Among the nutritional elements magnesium and cadmium daily fluctuations were detected in isolated cases, respectively. The diferences in their levels among samples taken from different women were statistically significant. We found significant correlations between xenobiotics and two major nutritional elements and between xenobiotics and biogenic elements in breast milk samples. We found strong positive correlations between Cd and Ca (R = 0.220), Cd and Mg (R = 0.201), Cd and Zn (R = 0.279), Cu and Ca (R = 0.347), Cu and Mg (R = 0.084), Zn and Mg (R = -0.089) and negative correlation between Pb and Ca (R = -0.295). Our results suggest that xenobiotics such as Cd and Pb are transported to women's milk during lactation, and their presence has an important influence on trace and nutritional elements in breast milk. Breastfeeding mothers should avoid situations in which they run the risk of xenobiotics interactions.

Evaluation of powdered infant formula milk as chelating agent for copper under simulated gastric conditions of a baby's stomach

The objective of this study was to determine the complexing capacity of four types of powdered commercial milks with copper(II) using square wave adsorptive stripping voltammetry. Two were types of cow milk adapted for babies under one year (A and B), one was soymilk (C) and the other was normal milk (D). Milk solutions were prepared following the instructions shown on the milk container, and they were mixed with a pepsin solution simulating a baby's stomach conditions (pepsin and salts concentration, pH and temperature). Complexing capacity was determined by titrating milk samples with aliquots of a standard copper solution until the peak current due to solvated or free copper ions was increasing. Assuming a 1:1 copper-milk complex, the apparent stability constant was found using the pseudopolarogram method. The log K'(Cu-milk) values were 4.9, 5.0, 3.0 and 5.1 for A, B, C and D types of milk, respectively. Voltammograms of the milk solution as a function of copper added show that the binding properties of the four types of powdered milk studied were different and that saturation of the four types, occurs at different copper concentrations. Concentrations obtained were: 4.9, 5.8, 1.1 and 10.1 mM for A, B, C and D types, respectively. The best complexing agent was the solution prepared with powdered milk D and the worst was that of C. This is important for the bioavailability of this element as a micronutrient.

Toxic and essential trace elements in human milk from Greek lactating women: association with dietary habits and other factors

The aim of this study was to determine the concentration of some essential and toxic metals in the colostrum and transitory human milk in conjunction with various factors that may influence their concentrations i.e. diet, supplementation, place of residence, smoking, as well as socioeconomic and somatometric characteristics. Zinc, iron, copper, manganese, cadmium and lead were measured by AAS in 180 colostrum samples from healthy lactating women collected on third day postpartum. A second milk sample was collected in 95 (53%) subjects 14 days later. Dietary habits were assessed by a 7-day food frequency questionnaire and various characteristics and socio-economic factors were also recorded. The mean (+/-standard deviation) values of colostrum samples were: Zn 4905 +/- 1725 microg l(-1), Fe 544 +/- 348 microg l(-1), Mn 4.79 +/- 3.23 microg l(-1), Cu 381 +/- 132 microg l(-1), Cd 0.190 +/- 0.150 microg l(-1), Pb 0.48 +/- 0.60 microg l(-1). All metals with the exception of copper were found in lower concentrations in transitory samples. Cadmium and lead weekly intakes were found to be below the Maximum Tolerable Weekly Intakes as they have been established for infants by WHO or NRC. Our results revealed: higher Pb concentration in the samples from urban areas; effect of smoking on Cu level; dietary habits seem to play a role in metal levels in human milk as the logistic regression models revealed.

Day-to-day variations in iron, zinc and copper in breast milk of Guatemalan mothers

OBJECTIVE

To assess the within-subject and between-subject coefficients of variation (CV) of iron, zinc and copper concentrations in the milk of Guatemalan mothers.

METHODS

We performed a cross-sectional study in lactating women who had delivered a healthy infant 1 to 6 months previously in two low-income peri-urban areas (San Bartolome Milpas Altas and Ciudad Peronia) and a low-income rural area (San Juan Chamelco) in Guatemala. Women infested with Ascaris lumbricoides or Trichuris trichiura received a single dose of albendazole (400 mg) or placebo. Two weeks after treatment, milk samples were collected on 3 or 4 consecutive days. Trace element concentrations in milk were measured by inductively coupled plasma/atomic emission spectrometry.

RESULTS

The instrumental error of the inductively coupled plasma/atomic emission spectrometry method, expressed as SD, was 0.04, 0.27 and 0.02 mg/L for iron, zinc and copper, respectively. Concentrations in milk samples collected from 47 mothers on 3 or 4 consecutive days, expressed as mean +/- SD, were 0.28 +/- 0.13, 2.03 +/- 0.37 and 0.29 +/- 0.07 mg/L for iron, zinc and copper, respectively. The within-subject CV was 46.1%, 18.2%, and 22.8% and the between-subject CV was 61.2%, 48.3% and 31.7% for iron, zinc and copper, respectively. Stage of lactation, infestation with intestinal parasites and residential area had a significant influence on milk zinc, copper and iron concentrations.

CONCLUSIONS

One sample of milk is sufficient to give a reliable estimate of the zinc concentration in milk. Two samples taken on consecutive days are required for a reliable estimate of iron and copper concentrations.

Macronutrient, mineral and trace element composition of breast milk from Japanese women

The aim of the study was to determine the concentrations of macronutrients and the mineral and trace element composition in maternal milk of Japanese women. We collected human milk samples from mothers living throughout Japan from December 1998 to September 1999, and defined as group A the 1197 samples among them that met the following conditions: breast milk of mothers who were under 40 years old, not in the habit of smoking and/or using vitamin supplements, and whose babies showed no symptoms of atopy and whose birth weights were 2.5 kg or more. We then analyzed their contents individually. We also analyzed the amino acid and free amino acid composition of the breast milk of pooled samples from various lactation stages. Large differences were found to exist among the contents of individual human milk samples. The mean contents of each component were as follows: energy, 66.3+/-13.3 kcal/100 mL; solid matter, 12.46+/-1.56 g/100 mL; ash, 0.19+/-0.06 g/100 mL; total nitrogen, 0.19+/-0.04 g/100 mL; lipids, 3.46+/-1.49 g/100 mL; carbohydrates, 7.58+/-0.77 g/100 mL; lactose, 6.44+/-0.49 g/100 mL; pH, 6.5+/-0.3; osmotic pressure, 299+/-14 mOsm/kg.H2O; chloride, 35.9+/-16.2 mg/100 mL; sodium, 13.5+/-8.7 mg/100 mL; magnesium, 2.7+/-0.9 mg/100 mL; phosphorus, 15.0+/-3.8 mg/100 mL; potassium, 47.0+/-12.1 mg/100 mL; calcium, 25.0+/-7.1 mg/100 mL; chromium, 5.9+/-4.7 microg/100 mL; manganese, 1.1+/-2.3 microg/100mL; iron, 119+/-251 microg/100 mL; copper, 35+/-21 microg/100 mL; zinc, 145+/-135 microg/100 mL; and selenium, 1.7+/-0.6 microg/100 mL. The content of each component varied greatly as the duration of lactation increased. In conclusion, it appears to be necessary to evaluate individual differences of human milk in order to perform valid research regarding infant formula.

Perinatal aspects of iron metabolism

Iron sufficiency is critical for rapidly developing fetal and neonatal organ systems. The majority of iron in the third trimester fetus and the neonate is found in the red cell mass (as hemoglobin), with lesser amounts in the tissues as storage iron (e.g. ferritin) or functional iron (e.g. myoglobin, cytochromes). Iron is prioritized to hemoglobin synthesis in red cells when iron supply does not meet iron demand. Thus, non-heme tissues such as the skeletal muscle, heart and brain will become iron deficient before signs of iron-deficiency anemia. Gestational conditions that result in lower newborn iron stores include severe maternal iron deficiency, maternal hypertension with intrauterine growth retardation and maternal diabetes mellitus. Stable, very low birthweight premature infants are also at risk for early postnatal iron deficiency because they accrete less iron during gestation, grow more rapidly postnatally, are typically undertreated with enteral iron and receive fewer red cell transfusions. Conversely, iron overload remains a significant concern in multiply transfused sick preterm infants because they have low levels of iron-binding proteins and immature antioxidant systems.

CONCLUSION

The highly variable iron status of preterm infants combined with their risk for iron deficiency and toxicity warrants careful monitoring and support in the newborn and postdischarge periods.

Neonatal iron nutrition

Preterm infants are prone to iron deficiency. Their total body iron content at birth is low and gets further depleted by clinical practices such as uncompensated phlebotomy losses and exogenous erythropoietin administration during the neonatal period. Early iron deficiency appears to adversely affect cognitive development in human infants. To maintain iron sufficiency and meet the iron demands of catch-up postnatal growth, iron supplementation is prudent in preterm infants. A dose of 2-4 mg/kg/day is recommended for preterm infants who are fed exclusively human milk. A dose of 6 mg/kg/day or more is needed with the use of exogenous erythropoietin or to correct preexisting iron deficiency. However, due to the poor antioxidant capabilities of preterm infants and the potential role of iron in several oxidant-related perinatal disorders, indiscriminate iron supplementation should be avoided.

Effectiveness of treatment of iron-deficiency anemia in infants and young children with ferrous bis-glycinate chelate

Forty infants, 6 to 36 mo old, with iron-deficiency anemia (hemoglobin < 11 g/dL) were matched and assigned to two groups. One group received FeS0(4) and the other received ferrous bis-glycinate chelate at a dose of 5 mg of Fe daily per kilogram of body weight for 28 d. Both groups had significant hemoglobin increases (P < 0.001), but only the group treated with ferrous bis-glycinate chelate had significant increases (P < 0.005) in plasma ferritin. Apparent iron bioavailabilities were calculated at 26.7% for FeS0(4) and 90.9% for ferrous bis-glycinate chelate. Regression analysis indicated that absorption of both sources of iron were similarly regulated by the body according to changes in hemoglobin. We concluded that ferrous bis-glycinate chelate is the iron of choice for the treatment of infants with iron-deficiency anemia because of its high bioavailability and good regulation.

Intrauterine device and maternal copper metabolism during lactation

The effects of intrauterine device (IUD) on maternal copper (Cu) metabolism during breastfeeding was studied in 95 volunteer mothers who chose to use non-hormonal contraceptive methods. They were divided into two groups that were inserted with the IUD-Cu 380A (n = 33), IUD-Cu 200B (n = 29), and a third group that did not use any IUDs served as control (n = 33). Endometrial biopsies, blood, and milk samples were collected before (at 10 weeks postpartum) and 6 weeks after insertion of device for the determination of metabolites associated with copper metabolism, namely, serum ceruloplasmin, and copper concentrations in breast milk and endometrium. Endometrial copper concentration increased in women using IUDs, but was statistically significant (p = 0.001) only in the IUD-Cu 380A group. The increase in endometrial copper concentration did not affect serum ceruloplasmin or milk copper concentrations.