Is Zinc safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Zinc. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
Zinc deficiency in exclusively breastfed infants can occur. Clinical features include facial and groin rash, diarrhea, hair loss, disinterest in feeding, and failure to thrive. One known cause is below-normal milk zinc levels due to maternal genetic mutations affecting mammary zinc transport proteins.[19] Zinc deficiency may also occur in infants born very preterm who are not supplemented with special human milk fortifiers designed for premature babies.[20] With both causes, direct administration of zinc drops to the infant quickly corrects the deficiency and alleviate the infant s symptoms. Acrodermatitis enteropathica is a congenital zinc deficiency disorder caused by genetic mutations affecting the infant s intestinal zinc transporter proteins. Breastmilk is protective against this disorder, and symptoms typically develop after weaning from breastmilk feeding.[19,21] Resuming breastmilk feeding, if possible, and direct infant supplementation with zinc drops are the recommended treatments.
Effects on milk supply
Certain variations in genes encoding mammary epithelial cell zinc transporter proteins are associated with reduced milk volume and altered milk content beyond zinc. This is not thought to be triggered by maternal zinc intake or zinc status and is not correctable with maternal zinc supplementation.[22]
Levels in milk
Zinc is normally present in human breastmilk, mostly bound to milk proteins.[2] Reported average milk zinc levels in colostrum range from 4 to 9 mg/L, decreasing to 2 to 4 mg/L by 1 to 2 weeks postpartum, then stabilizing at 1 to 2 mg/L beyond two weeks, eventually falling below 1 mg/L by 9 months.[2-10] Levels are similar between fore- and hindmilk.[3] Mothers with less than adequate zinc intake may have slightly lower milk zinc levels compared to mothers with adequate intake, although the reported differences are of marginal clinical relevance.[9] In a U.S. study of sixty-three postpartum, lactating, mostly white, women taking a daily prenatal or multi-vitamin, those on a vegan or vegetarian diet had similar milk zinc levels compared to those on an omnivore diet.[11] Zinc levels may be higher in preterm milk, although only limited data are available. In a study from Rio de Janeiro, Brazil, three mothers who gave birth between 28 and 36 weeks gestation had a median milk zinc level of 2.9 mg/L after 2 weeks postpartum compared to 1.2 mg/L in four mothers who gave birth at term.[2] Maternal Levels. Forty mothers in Maryland were randomly given a once daily 25 mg elemental oral zinc supplement as zinc oxide or placebo beginning the day after delivery and continuing for 9 months. Prenatal vitamins without zinc were used during pregnancy, and the estimated average dietary zinc intake was similar between the two groups at around 11 to 12 mg daily throughout the study period. Milk was collected at 1 and 2 weeks, and at 1, 3, 6, and 9 months after delivery. Levels were approximately 4, 3.5, 2.7, 1.3, 1, and 0.65 mg/L, respectively, in both groups.[12] In Colorado, 19 pregnant and 52 postpartum women within two weeks of delivery were randomized to receive a once daily 15 mg elemental zinc oral supplement as zinc sulfate or placebo for nine months. Milk samples were collected at baseline and then monthly. The postpartum estimated average daily dietary zinc intake was similar
Source: NIH LactMed (National Library of Medicine).
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.