Assessment of Breast Milk Iodine Concentrations in Lactating Women in Western Australia

Abstract

Breast-fed infants may depend solely on an adequate supply of iodine in breast milk for the synthesis of thyroid hormones which are essential for optimal growth and cognitive development. This is the first study to measure breast milk iodine concentration (BMIC) among lactating women in Western Australian (n = 55). Breast milk samples were collected between 2014 and 2015 at a mean (±SD) of 38.5 (±5.5) days post-partum. The samples were analysed to determine median BMIC and the percentage of samples with a BMIC < 100 µg/L, a level considered adequate for breast-fed infants. The influence of (a) iodine-containing supplements and iodised salt use and (b) consumption of key iodine-containing foods on BMIC was also examined. The median (p25, p75) BMIC was 167 (99, 248) µg/L and 26% of samples had a BMIC < 100 µg/L. Overall, BMIC tended to be higher with iodine-containing supplement usage (ratio 1.33, 95% confidence interval (CI) (1.04, 1.70), p = 0.030), cow’s milk consumption (ratio 1.66, 95% CI (1.23, 2.23), p = 0.002) and lower for Caucasians (ratio 0.61, 95% CI (0.45, 0.83), p = 0.002), and those with secondary school only education (ratio 0.66, 95% CI (0.46, 0.96), p = 0.030). For most women, BMIC was adequate to meet the iodine requirements of their breast-fed infants. However, some women may require the use of iodine-containing supplements or iodised salt to increase BMIC to adequate levels for optimal infant nutrition.

Suboptimal Iodine Concentration in Breastmilk and Inadequate Iodine Intake among Lactating Women in Norway

“…There is no scientific consensus on the BMIC that represents a sufficient iodine intake, and a wide range of BMIC values have been reported in areas with varying iodine sufficiency [ 3 , 29 , 40 ]. BMIC typically ranges from <50 µg/L in iodine-deficient areas [ 41 ] to 100–200 µg/L in areas with iodine sufficiency [ 3 , 29 , 40 , 42 , 43 ]. A recent metabolic balance study proposed an estimated average requirement (EAR) of 72 µg/L in breastmilk to infants from 2–5 months of age [ 44 ].…”

“…Approximately 35% of the lactating women in the study sample were not born in Norway; however, we found no differences in BMIC, UIC, or iodine intake related to country of origin. Jorgensen et al found that median BMIC was lower for Caucasian than for non-Caucasian women [ 43 ].…”

Iodine deficiency during lactation: why supplementation is so important?

“…Як і для вагітної, для мате рі годувальниці підвищити надходження йоду із продуктами харчування є досить складним завданням, оскільки рекомендувати вживати більшу кількість ЙС неможливо, а морепро дукти цій особливій категорії населення не можна споживати частіше 3-4 разів на тиждень з огляду на високий вміст важких металів. [11]. Системний аналіз досліджень різних років переконливо доводить зв'язок між запрова дженням програм загальної обов'язкової йоди зації солі в країні та вмістом йоду в грудному молоці.…”

“…2). [2,8,[11][12][13][14]. Вважається, що збільшити йодне надходження необхідно ще на етапі преграві дарної підготовки за три місяці до заплановано го зачаття, продовжувати сапліментацію весь період вагітності та годування грудьми.…”

Nutrients in Infancy: Progress and Prospects

“…It is estimated that 1.9 billion people live in areas of the world subject to subclinical iodine deficiency, which is important for cognitive development in infancy [ 6 ]. The study by Jorgenson and her colleagues demonstrates that, in Australia, with a food fortification program and the recommendation that pregnant women take 150 mcg iodine supplements daily, the iodine content of breastmilk is generally adequate [ 7 ].…”