by Anne Eglash MD, IBCLC, FABM
Do we need to be concerned about the zinc level in breastmilk? According to a 2017 article Zinc Concentrations in Human Milk and Infant Serum in the first 6 Months of Lactation zinc is essential as a component of at least 300 enzymes in breastmilk. It also plays a role in metabolism of proteins, carbohydrates, and lipids. Further, it is essential for cell differentiation and body growth.
Zinc concentrations are highest in colostrum, and gradually decline in breastmilk over time. Zinc levels are also higher in foremilk than in hindmilk. The maternal zinc intake does not guarantee sufficient zinc in breastmilk, because there are zinc transporter proteins responsible for moving the zinc from the milk-producing cells into the breastmilk, and these transporter proteins are occasionally insufficient due to genetic mutations. Some of these genetic mutations have been found to be hereditary.
A recent published case report of a 4-month old infant with symptoms of zinc deficiency exemplifies how a mother with a normal serum zinc level can have low zinc levels in breastmilk due to a zinc transporter gene mutation.
What do you think are signs of zinc deficiency? (choose 1 or more)
- Impaired sense of taste
- Poor appetite
- Slowed growth and development
- Immune system deficiencies
- Perioral rash
See the Answer
All are true
Pediatr Dermatol. 2017 Mar;34(2):e104-e105
Transient Neonatal Zinc Deficiency Caused by a Novel Mutation in the SLC30A2 Gene.
Liew HM, Tan CW, Ho CK, Chee JN, Koh MJ
This is a case report of a 4-month-old full-term, fully breastfed boy who presented with a persistent periorificial and groin rash associated with poor weight gain and irritability. His serum zinc level was low. The mother's breast milk zinc level was found to be low despite her serum zinc levels being normal, confirming the diagnosis of transient neonatal zinc deficiency. Mutational analysis revealed a novel mutation in the mother's SLC30A2 gene, which encodes a zinc transporter expressed in mammary gland epithelial cells.
Milk Mob Comment by Anne Eglash MD, IBCLC, FABM
Zinc deficiency in exclusively breastfed infants is rare. However, this case serves to remind us to include zinc deficiency as part of the differential diagnosis in breastfed infants who are not gaining well, have a poor appetite, developmental delay, and possibly a chronic rash. The infant’s zinc level should be measured, not the maternal zinc level. Supplementing the mother with zinc will not necessarily increase the zinc level in the breastmilk. Infants with zinc deficiency should be supplemented with 2mg/kg of zinc sulfate daily, and they may continue to breastfeed. All infants should be offered complementary foods that contain zinc, including meat, poultry, oysters, spinach, nuts, beans, and mushrooms.