Chapter 20 - Iodine Transfer Through Mother’s Milk: The Influence of Bromide

Abstract

This chapter discusses the influence of a high bromide intake in lactating rat dams on iodine and bromide transfer through mother's milk to the suckling and the effects on iodine metabolism. Very high bromide intake in the dams caused a decrease in iodide accumulation in the mammary glands, and also an increase in iodide elimination through the kidneys. Two marked consequences caused by high bromide intake were observed in the dams: decline in the extent of diet and water consumption during the nursing period, and a conspicuous drop in the production rate of mother's milk. The observed pronounced decrease in iodine transfer to the young through mother's milk and/or an increase in the bromide concentration in milk caused a very significant decrease in the body weight increments in the pups. Enhanced bromide levels in the dams also adversely affected the thyroid gland of their young and induced hypothyroidism in them. Consequences of a decreased iodine transfer and/or an increased bromide concentration in the mother's milk marked hypothyroxinemia both in the dams' bodies and in the bodies of their suckling. It also resulted in a very significant decrease in the body weight increments in the pups. The exact mechanism(s) of bromide interference with iodine metabolism and with postnatal developmental processes in the young remains unresolved.