| dc.description.abstract | Background: Iodine is an essential element for foetal and infant growth and for development of the central nervous system. Lactating women and infants are exceptionally vulnerable to iodine deficiency and lack of thyroid hormones during infancy may lead to permanent brain damage. Despite the importance of iodine for infant health, few studies have assessed iodine concentration in human milk and there is currently no existing data on iodine status of lactating women in Norway.
Objective: The overall aim of this study was to assess iodine status in lactating women by assessing iodine concentrations in breast milk (BMIC) and urine (UIC) and compare them with WHO cut-offs, and by evaluating estimated iodine intake from food and dietary supplements.
Methods: A cross-sectional survey was performed in lactating women in five randomly selected Mother and Child Health Centres in Oslo during October and December 2016. A total of 175 lactating women between 2nd and 28th weeks postpartum participated. Iodine concentration in breast milk and spot urine samples were analyzed by inductively coupled plasma mass spectrometry (ICPMS-QQQ). Participants also provided information on iodine intake from food and supplements covering the last 24-hour (24h) and the habitual iodine intake (food frequency questions).
Results: The median and 25th and 75th percentiles (P25, P75) BMIC was 68 (45, 98) µg/L and median UIC was 64 (39, 95) µg/L. A total of 76% had BMIC <100µg/L, 18% had BMIC between 100-200µg/L and only 6% women had BMIC between 200-600µg/L. A total of 81% had UIC <100µg/L. Habitual iodine supplement use was reported by 29%, of which 18% had taken an iodine-containing supplement the last 24-hour. The median (P25, P75) habitual iodine intake from food and total iodine intake (food and supplements) was 106 (79, 138) µg/day and 135 (94, 212) µg/day, respectively. The median (P25, P75) 24-hour iodine intake from food and total iodine intake (food and supplements) was 121 (82, 162) µg/day and 134 (95, 222) µg/day, respectively. Infant’s age, iodine-containing supplement intake in the last 24-hours, smoking status and UIC predicted BMIC, explaining 33% of the variance.
Conclusions: Approximately ¾ of the lactating women had inadequate iodine concentration in breast milk and urine. This was supported by inadequate iodine intake from food and supplements. Findings of this study indicate inadequate iodine status in lactating women and claim for further attention to iodine status during lactation | language |
