Double Burden of Malnutrition: Toxic Metals in Breast Milk May Limit the Amounts of Micronutrients Available to Infants through Breast Milk

Abstract

Background: The amounts of micronutrients in the diets of infants, and the factors that influence them needs to be monitored at the population level in order to avert detrimental developmental defects that impose lifetime-limitations on an infant’s regulatory and defense systems. This study therefore, sought to evaluate if increasing levels of the toxic metals, Hg, Pb and Cd in breast milk will result in reducing amounts of the micronutrients Zn, Se and Cu in breast milk. Methods: Breast milk samples of 114 women living in two mining areas (57 women each) in Ghana, whose babies’ amounts of breast milk intake at three months postpartum, and amounts of toxic metals had previously been determined in a prospective study, were analyzed for micronutrients by a combination of acid and microwave digestion, and quantifications were by two different modes (hydrogen and helium) of Octapole Reaction System Inductively Coupled Plasma Mass Spectrometer (7500 ce. Agilent), equipped with an ASX-510 Auto-sampler (Cetac). Results: All the breast milk specimen collected contained detectable amounts of Cu, Zn, both at levels less than have been previously reported, and Se. For specimen that did not contain Pb the amount of Se ranged from about 110 to 245 ng/g of milk, however, as the amount of Pb increased, the corresponding highest detected amount of Se reduced steeply, resulting in a right-angle triangle-shaped scatter plot. Similar relationships were observed between other toxic metals and micronutrients studied. A curve fitting regression analysis showed significant quadratic and cubic relationships between the amounts of Hg and Se, as well as between Pb, As and Cu. Conclusion: The results clearly suggest a double burden of malnutrition in these mining areas, where high loads of maternal toxic metals in breast milk, related significantly with a progressive reduction in the amounts of the micronutrients Cu and Se in breast milk, potentially reducing in infants’ intake of these micronutrients.