What nutrient's level in breast milk is maintained at the expense of the mother's intake if inadequate?

The nutrient in breast milk that is maintained at the expense of the mother's intake, if inadequate, is calcium. During lactation, a mother's body prioritizes the delivery of calcium to the breast milk to ensure that the infant receives an adequate supply for bone development and other metabolic functions necessary for their growth. If the mother’s dietary intake of calcium is insufficient, her body compensates by drawing from her own skeletal stores to maintain the calcium levels in her breast milk. This can potentially put her own bone health at risk if the deficiency persists.

Calcium's role is critical since it is vital not only for the baby's development but also plays a significant part in the overall health of the mother during this time when her body is under increased demands. This unique physiological adjustment highlights the importance of adequate maternal nutrition during lactation, particularly regarding calcium intake, to prevent adverse effects on both the mother and the infant.