Evaluation of Zinc, Copper and Iron Concentrations in Breast Milk of Mothers Belonging to Different Economic Classes and their Correlations with Infants Growth

Taking into account the importance of micronutrients in health and growth of the infants, the concentrations of zinc, copper, and iron in breast milk of mothers belonging to different economic classes and their effects on infants’ growth were investigated.

Milk samples and information on personal characteristics, anthropometric and 24-hour food recall were collected from 90 lactating women belonging to 3 different socioeconomic classes who had exclusively breastfed their 90-120 day old infants. Concentrations of trace elements were analyzed using atomic absorption spectrophotometry and dietary information of subjects was analyzed by Nutritionist III software program. Statistical tests included Multiple Regression, ANOVA test and Independent t-test.

The mean zinc concentrations in mothers’ breast milk belonging to high, moderate and low socioeconomic groups were 1.6, 1.9 and 2.3 mg/l, respectively. Copper levels were 0.41, 0.47 and 0.85 mg/l, respectively and iron levels were 0.75, 0.8 and 0.9 mg/l, respectively. Group comparisons showed significant differences (P<0.05). Although association between mineral concentrations and WAZ or HAZ of infants was not significant, the WAZ of infants whose mother's milk zinc concentration was more than 2 mg/l was significantly higher than WAZ of other infants (P<0.03). Despite no significant correlation between trace element intake and trace elements in milk, negative and significant correlations between maternal age and milk minerals concentrations were observed.

The concentration of studied trace elements in milk of mothers with low economic status was higher but was not related to intakes and it was probably related to mother's age. So, dietary consultations for older lactating mothers are needed.