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High Doses of Zinc in Williams Syndrome

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  • High Doses of Zinc in Williams Syndrome

    We have a mother who is taking a high dose of zinc (220mg three times daily) as a treatment for Williams Syndrome. Her baby is late pre-term (35 weeks). Is it ok to breastfeed in this situation?

  • #2

    The RDA of zinc is 12-15mg a day. Dr Hale recommends not to exceed 25-50mg a day. Zinc toxicity can occur in adults at doses greater than 200-225mg a day. We do not know how much zinc could transfer into breast milk. Zinc toxicity can cause abdominal pain, nausea, vomiting, headaches, anemia and seizures, it can also cause a suppression of iron and copper absorption. We could not recommend the safety of these high doses in a breastfeeding mother.

    Sandra Lovato R.N.
    InfantRisk Center


    • #3
      Is Dr. Hale available to comment on this? We found some evidence suggesting that the maternal intake of zinc does not correlate with the zinc levels in breastmilk. And so we just want to be as sure as possible that if we are suggesting to this mother not to breastfeed (as you suggest above) that we are doing so appropriately. Thank you.


      • #4

        The problem with Zinc is that the levels early postpartum are reportedly quite high and the infants absorption is apparently higher as well.

        Interestingly, absorption of dietary zinc is nearly twice as high during lactation as before conception. In 13 women studied, zinc absorption at preconception averaged 14% and during lactation, 25%.[1] There was no difference in serum zinc values between women who took iron supplements and those who did not although iron supplementation may reduce oral zinc absorption. Zinc absorption by the infant from human milk is high, averaging 41%, which is significantly higher than from soy or cow formulas (14% and 31% respectively). Minimum daily requirements of zinc in full term infants vary from 0.3 to 0.5 mg/kg/day.[2] Daily ingestion of zinc from breastmilk has been estimated to be 0.35 mg/kg/day and declines over the first 17 weeks of life as older neonates require less zinc due to slower growth rate.

        Supplementation with 25-50 mg/day is probably safe, but excessive doses are discouraged. Another author has shown that zinc levels in breastmilk are independent of maternal plasma zinc concentrations or dietary zinc intake.[3] Other body pools of zinc (i.e., liver and bone) are perhaps the source of zinc in breastmilk. Therefore, higher levels of oral zinc intake probably have minimal effect on zinc concentrations in milk but excessive doses are not recommended.

        I'd suggest that if this mom breastfeeds while consuming such high oral doses of zinc, it would be advisable to monitor the zinc levels in the breastfed infant.

        Tom Hale Ph.D.

        1.Fung EB, Ritchie LD, Woodhouse LR, Roehl R, King JC. Zinc absorption in women during pregnancy and lactation: a longitudinal study. Am J Clin Nutr 1997; 66(1):80-88.
        2.Drug Facts and Comparisons 1997 ed. ed. St. Louis: 1997.
        3.Krebs NF, Reidinger CJ, Hartley S, Robertson AD, Hambidge KM. Zinc supplementation during lactation: effects on maternal status and milk zinc concentrations. Am J Clin Nutr 1995; 61(5):1030-1036.