THE EFFECT OF LACTATION TIME ON THE MACRONUTRIENT AND MINERAL-COMPOSITION OF MILK FROM VENEZUELAN WOMEN

Human milk is considered the ideal food for the infant and it has been extensively used to estimate its nutrient requirements. The objective of this paper was to determine the effect of lactation time on the ma cronutrient an mineral content of milks obtained from Venezuelan women and also to compare this with the established nutrient requirements o f the infant. For this purpose 83 milk samples from 45 low income moth ers were analyzed at the colostrum (48 h to 54 d) and mature states of lactation (1,3 and 6 months). The results showed that colostrum had a higher protein and a lower fat content than mature milks whereas its content of energy and carbohydrate was similar to mature milk. The iro n end calcium content of the milk remained unchanged during the whole study whereas Zn and Cu decreased and increased with lactation time re spectively. In contrast, phosphorous and magnesium increased up to 3rd month of lactation and remained constant there after. The macronutrie nt content of 850 ml of the analyzed milk almost completely fulfilled the daily infant requirements established in the US (RDA) and Canada ( RN1). The mineral content of this volume of milk however was insuffici ent to cover tile infants requirements particulary those established i n the US. The most notoriuos deficiency in these milks was in Fe since they could fulfill only 11% the infants RDA for this mineral. The inf ant mineral requirements established in Canada are substantially lower than those defined in the US and therefore the analyzed milks could t otally fulfill the Canadian infant daily requirements of Mg, Fe and Ca and more than 70% and 80% of the requirements of Zn and P. In general , the results of this study showed that the nutrient content of the an alyzed milks agree well with those reported in the literature for wome n from different parts of the world including developed and underdevel oped areas. At the same time they pointed out the differences in the d efinition of the infant nutrient requirements set by different countri es and also emphasize the fact that human milk, which by definition is the natural source of nutrients for the human infant apparently is in capable of fulfilling its daily requirements.