Maternal breast milk is a unique biological matrix that contains essential micronutrients. Potentially heavy metals may also affect infants’ health and growth through maternal breast milk. The purpose of this study was to determine and compare the essential elements and heavy metals of maternal breast milk of nursery mothers residing in Şanlıurfa province, Turkey. Maternal breast milk concentrations of sodium, magnesium, phosphorus, potassium, calcium, iron, copper, zinc, arsenic, and lead were analyzed in a random sample of the first time in urban and suburban nursery Turkish mothers (
Maternal breast milk (MBM) is a unique biological matrix of nutrition for infants. Breastfeeding is vital for optimal health, growth, and development with its macro- and micronutrients, including essential elements [
Essential elements in MBM are crucial for ideal growth and development of infants. There are a lot of benefits associated with MBM, such as decreasing the morbidity, mortality, and incidences of diseases [
Concentration data on some essential elements and heavy metals in MBM of nursery mothers from different countries analyzed with different techniques such as flame photometry [
The aim of this study is to provide and access the information of concentrations of essential elements in MBM from nursery mothers who are residing in Şanlıurfa province of Turkey using a sensitive method and also compare the relations between essential elements and socioeconomic conditions, residing areas, and using copper equipment for food preparation.
Samples were collected from 42 nursery mothers with an average age of
Data of nursery mother and the infants’ status.
Parameter | Total number | Percentage (%) | Min | Max | Mean ± SD |
---|---|---|---|---|---|
Age of infant (day) | 42 | 100.0 | 3 | 520 | 162 ± 139 |
Age of mother (year) | 42 | 100.0 | 17 | 44 | 28.3 ± 7.08 |
Income rate < minimum wage | 21 | 50.0 | |||
Income rate ≥ minimum wage | 21 | 50.0 | |||
Residing in urban area | 25 | 59.5 | |||
Residing in suburban area | 17 | 40.4 | |||
Using copper equipment | 13 | 31.0 | |||
Not using copper equipment | 29 | 69.0 |
Mixed calibration standards of sodium, magnesium, phosphorus, potassium, calcium, iron, copper, zinc, arsenic, and lead were prepared from dilutions of stock solutions (Agilent Japan (Lot Number: 10-160YPY2)). TraceSELECT grade of nitric acid (65.0% concentrated, Merck, Germany) and hydrogen peroxide (30.0% concentrated, Merck, Germany) were used for sample digestion.
Ultrapure water was provided in the laboratory (18.2 MΩ/cm at 25°C) by MES MP Mini pure, (Turkey) device. Every plastic and glassware were cleaned in acid bath (5% nitric acid (laboratory grade, Merck, Germany)) for 24 h and rinsed with ultrapure water and dried before use. The gas 99.9990% Argon was supplied by Linde Gases (Linde Group, Turkey). Whole solutions were prepared with ultrapure water.
Elements were analyzed on Agilent 7500 ce with an octopole reaction system inductively coupled plasma-mass spectrometer (Agilent Technologies, Japan) with an autosampler (Cetac ASX-520) and a nebulizer (Agilent Technologies, Japan).
MBM samples were analyzed by ICP-MS after microwave-assisted acid digestion. 1.0 mL of each sample and blank samples was digested with 4.0 mL of 65% (v/v) HNO3, and 2.0 mL of 30% (v/v) H2O2 in PTFE vessels. Microwave acid digestion procedure was as follows: firstly up to 120°C for 15 min, for the second step constant for 10 min; up to 160°C in 20 min; and finally constant for 15 min; at the end a cooling stage (30 min) was done in room temperature and the samples and blanks were diluted to 50 mL with ultrapure water.
The isotopes 23Na+, 24Mg+, 26Mg+, 31P+, 39 K+, 44Ca+, 56Fe+, 63Cu+, 66Zn+, 75As+, and 208Pb+ were detected. All samples were analyzed in triplicate. These isotopes were preferred to maximize the sensitivity and minimize interferences.
Limit of quantification (LOQ) and limit of detection (LOD) were calculated for ten times and the recovery of 12 elements (Na, Mg, P, K, Ca, Fe, Cu, Zn, As, and Pb) in raw milk samples was between 92.4 and 124.1% as shown in Table
Quantification and detection limits.
Element | LOQ | LOD | Concentration range of standard solution |
---|---|---|---|
Na (mg/L) | 315 | 10.0 | 1–2000 |
Mg (mg/L) | 48.6 | 4.60 | 1–100 |
P (mg/L) | 562 | 35.0 | 10–1000 |
K (mg/L) | 1413 | 100 | 10–1000 |
Ca (mg/L) | 678 | 22.0 | 10–1000 |
Fe (mg/L) | 2.53 | 0.40 | 0.1–1000 |
Cu (mg/L) | 0.06 | 0.01 | 0.01–100 |
Zn (mg/L) | 1.81 | 0.20 | 0.1–100 |
As ( | 0.04 | 0.01 | 0.1–100 |
Pb ( | 0.04 | 0.01 | 0.1–100 |
With a view to impose the integrity of the analyses, the same concentrations of each element as in the original sample were added to a sample and performed in the same microwave digestion procedure as the samples.
Statistical analyses were carried out using SPSS 11.00 (SPSS Inc., Chicago, IL, USA). For bivariate analyses of variables, nonparametric Spearman’s correlation coefficient was used.
Ethics committee approval was obtained from Medical Faculty of Harran University (74059997.050.01.04/65). Informed consents were obtained and signed by the participating nursery mothers to protect the participants’ privacy, personal and clinical data, and MBM samples used only for this study purpose.
The nursery mothers included in this study were on the average age of 17–44 (
Concentration of essential elements and heavy metals of MBM samples.
Min | Max | Mean ± SD | |
---|---|---|---|
| |||
Na (mg/L) | 44.7 | 1703 | 330 ± 417 |
Mg (mg/L) | 12.7 | 85.9 | 32.6 ± 15.5 |
P (mg/L) | 84.0 | 300 | 156 ± 46.3 |
K (mg/L) | 161 | 903 | 488 ± 147 |
Ca (mg/L) | 90.0 | 276 | 193 ± 53.2 |
Fe (mg/L) | 0.45 | 5.11 | 1.65 ± 1.43 |
Cu (mg/L) | 0.08 | 2.02 | 0.54 ± 0.46 |
Zn (mg/L) | 0.45 | 15.8 | 2.89 ± 3.23 |
| |||
As ( | <1 | <1 | <1 |
Pb ( | <1 | <1 | <1 |
Sodium levels in MBM samples ranged between 44.7 and 1703 mg/L and significantly correlated with copper (
MBM phosphorus concentrations were between the level of 84–300 mg/L, with a mean level of
Potassium concentrations of MBM varied between 161 and 903 mg/L. The content of potassium was positively correlated with zinc (
Calcium concentrations of MBM were in the range of 90–276 mg/L with a mean level of
The mean concentration of iron in MBM was
The zinc concentrations were positively correlated with sodium (
In this study, the results showed the differences in essential elements and heavy metals concentrations in MBM of nursery mothers residing in Şanlıurfa, Turkey. Specifically, nursery mothers from the suburban area (Eyyübiye) of Şanlıurfa tended to have lower intake concentrations of calcium assessed as compared with nursery mothers residing in urban areas (Haliliye and Karaköprü). As a result, MBM from nursery mothers residing in suburban area (Eyyübiye) were of poorer nutritional quality that has obvious implication for infants nutrition. Arising from this result, family population was crowded and socioeconomic levels of these families were low. The results of this study were parallel with Qian et al.s’ [
Calcium is the principal element of skeleton system that improves bone mineral density in infants. Our findings show that maternal calcium intake was lower in suburban nursery mothers than other participants of this study. Qian et al. [
There is evidence that sodium levels in infancy may have a long-term effect on blood pressure. The observation was that mean concentrations of sodium were higher than the previous studies [
MBM samples seem to contain enough concentration of magnesium as there has not been a report of magnesium deficiency in breastfed infants [
We also found that phosphorus concentrations were in a negative correlation with lactation period. The measured phosphorus concentrations in MBM samples ranged within 84–300 mg/L with an average level of
Potassium is an intracellular cation [
There have been few reports about iron content in MBM [
The mission of essential elements in biological functions makes them especially significant for nutrition of infant. It is noted that an infant is well protected so long as certain age by maternal homeostatic processes in the event of iron, copper, and zinc [
Zinc and copper are essential elements which support development and represent significant levels in MBM [
It is presumed that the transition of copper from blood to milk regulated transfer by the mammary gland epithelium [
By detecting the concentrations of heavy metals (arsenic and lead) of MBM, we estimated that no influences from the maternal intake or environmental exposure to these elements by reason of the concentrations were below the detection limit. This result may be because the Şanlıurfa province is away from the industry. Compared with concentrations reported in the literature [
We should be noted that MBM samples were obtained in one-time collection. Next research needed the composition of MBM varying on a time to time basis. Serial analyses of MBM samples in repeated times should address the concentrations of essential elements and heavy metals of Turkish mothers.
In brief, our results agree on the whole with previous reports about the essential element composition of maternal breast milk but it was clearly understood that there is a large standard variation in the composition of essential elements such as Ca, Fe, and Zn. We confirmed that the composition of human milk is affected by various factors such as residing area and using copper equipment.
In conclusion, we found a significant correlation in MBM concentrations between nursery mothers from urban and suburban areas of Şanlıurfa. More researches at multiple-time compositional studies are warranted to detect the concentrations for identifying appropriate interventions to ensure healthy growth and development of breastfed infants.
The authors declare that there are no conflicts of interest regarding the publication of this paper.