Macronutrients in Human Milk: Colostrum Lactose but Not Fat or Protein Predicts Mature Human Milk Content

Aim. To study longitudinal macronutrient concentrations of colostrum and mature human milk (HM) and test the hypothesis that colostrum concentration of a given macronutrient might predict the concentration of this macronutrient in mature milk. Methods. We collected samples of expressed HM obtained from mothers of full-term infants. Each mother contributed 2 samples of HM—the first during 72 hours after labor (colostrum) and the second after 14 days. Macronutrient contents of the samples were measured using infrared transmission spectroscopy. Results. In all, 57 women were recruited. Only 44 of them gave both colostrum and 14-day samples. The energy, fat, and carbohydrate content of mature milk was significantly higher than that in colostrum, whereas the opposite was found for protein content. There was no significant relationship between maternal weight for height and protein, fat, or lactose content at any stage. Energy, fat, and protein content in colostrum did not correlate with values in mature milk. In contrast, the lactose content in mature milk was highly correlated with that of colostrum (R2 = 0.47, P <.0001). Conclusion. Energy, fat, and protein content in colostrum do not predict values in mature milk. In contrast, lactose content in mature milk is highly correlated with that in colostrum.