Mothers milk iodine content

Figure 28.5 shows the iodine concentrations in urine and milk from nonsmoking and smoking mothers, and in urine from their neonates. Whereas urinary iodine concentrations were not different between groups of mothers, the iodine content of breast milk and of neonatal urine was reduced to around 50% if the mother was a smoker. This effect of smoking varied with the cotinine concentrations in mothers, and with the levels of thiocyanate in serum from the mothers and in cord serum (Laurberg et al., 2004). 

Once the pups are born 3i several mechanisms appear to protect the brain from T3 deficiency during an important period of maturation, which is post-natal in rats. The number of pups is reduced in LID (8.8 + 0.6) versus LID + I litters (11.2 + 0.6). Although the maternal intake of iodine is about 4 % of that of the LID + 1 mothers, the milk iodine content is only reduced to 22 %, that is, there is a five-fold increase as regards the... 

Figure 28.6 Maternal smoking and neonatal iodine nutrition. Breast-milk iodine and infant s urinary iodine content expressed as fraction of the mother s urinary iodine concentration. Both are measures of iodine transfer from mother to child during breastfeeding. The infant s urinary iodine content is expressed as a fraction of miik iodine content and is an inverse measure of iodine retention in the infant. Reproduced from Laurberg et al., (2004) with permission.

The mean iodine content of expressed breast milk produced by the mothers of the cohort was used to calculate individual iodine intakes for their infant. The mean value was lO.lmcg/dl, with a wide range of individual iodine contents from 4 to 28 mcg/dl. It is possible that expressed breast milk with low iodide content came from mothers who themselves were iodine deficient. Pilot observations... 

Iodine concentration was determined using a modification of the chloric acid digestion method described by Benotti and Benotti for serum. The iodine content of mothers nulk is shown in Table 50.3. Seventy-six percent of the samples had an iodine concentration between 10 and 30p,g/100ml. No statistically significant differences were found between samples of women with premature and term delivery, or between different times during the lactation period. Mean values for the iodine content of breast milk are quite variable. Breast milk is the best source of iodine for the newborn baby. 

The US recommendation of 40 pg/day in early infancy (0-6 months) is based on the assumption that an infant may get 30 to 50 pg iodine per day in milk from an adequately fed mother. This represents for infants aged 0 to 6 months approximately 8 pg/kg/day, and 7 pg/100 Kcal Such an intake is reached when the iodine content of milk is 5 pg/dl, which... 

In accordance with these findings and with the experience collected in experiments with animals, the iodine content of mother s milk first increased very slowly from 14 Mg/1 in 1982 to 19 iag/1 in 1987. In 1991, however, - apparently after filling up the iodine pool - it reached 36 Mg/1 (Groppel et al., 1991). 

Nearly 50 % of Hungarian population is supplied by drinking water with less than 10 /ug/L and 30 % with 11-25 /jg/L iodine, however it varies widely in the country, and in the same county. Iodine content of breast-milk was found in average of 4,2 ug/dl in 173 samples from 60 mothers on the postpartum... 

Consequently, the workshop recommends specific monitoring of iodine intake of mothers and infants in Europe by periodic analysis of urinary iodine levels, and to the extent feasible, of serum TSH and thyroid hormone measures. The daily intake of iodine should be at least 200 pg in pregnant and lactating women and 90-120 pg in young infants. To reach these objectives, the mothers diet should be systematically supplemented with iodine whenever necessary, by vitamins/minerals tablets as prescribed by physicians. Breast milk is the best source of iodine for the infant, and exclusive breast feeding for 4-6 months should be encouraged. However, when circumstances require that infants receive formula, the iodine content of formula milk should be increased fiom the traditional recommendation of S pg/dl milk to 10 pg/dl for full term and 20 pg/dl for premature babies. 

No studies of humans have demonstrated inhibition of iodide transport into breast milk of mothers from thiocyanate in diet. In many countries the most important determinant of thiocyanate levels in blood is tobacco smoking, as discussed above, and smoking is associated with similar increases in thiocyanate in blood as may be found from diets with high cyanide content. We therefore investigated the effect of maternal smoking on iodine transfer to the breast-fed neonate. 

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