Recommended daily intakes iodine content

Essential trace elements with their functions in enzymes and hormones are distributed in different parts of the body. Iodine is special. Some 75% of the total iodine content in the human body (about 14 mg) is found in the thyroid gland, a small organ in the neck. There, it participates in the formation of the important thyroid hormone, thyroxine. This is vital for normal mental and physical development and for regulating the body s metabolism. A recommended daily intake is 100-200 pg. Deficiency of iodine will cause goitre. This has to be treated by additional potassium iodide or iodine casein. In developed countries, iodine deficiencies are now rare because iodine is added to table salt. 

The daily protein intake per kg recommended for each age (Table 41.1) was used to calculate the total protein for a representative weight appropriate to the age (Child Growth Foundation, 1996) the derived amount of protein was then used to calculate the daily intake of iodine. The protein and iodine contents, and the specified recommended age range and indications for use of the enteral preparations, were taken from the manufacturers literature. Readers should note that the temporal recommendations for daily iodine intake from birth through childhood, adolescence and into adulthood do not coincide chronologically with recommendations made for amino acid or protein intakes (Tables 41.1 and 41.2). 

Analysis of the iodine content in representative meals prepared with iodinated salt at the university canteen showed a mean iodine content of 72pg/meal, corresponding to nearly half of the WHO recommended daily iodine intake for adults (150pg/day) (WHO, 2001). Of note, iodine content in the individual menus differed considerably, ranging from 18 to 136.5 pg/meal (Table 43.5). 

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. 

The key features of most low-iodine diets with reference to the major sources of iodine contributing to daily iodine intake are discussed below, and are summarized in Table 99.4. As discussed, there is only limited uniformity between sources of information as to the content of a low-iodine diet, partly due to geographical and dietary variations. The recommendations of the British Thyroid Association (2002) for patients, adapted in Table 99.5, are for example not identical to the much lengthier advice provided by the Thyroid Cancer Survivors Association. Patients need to be aware that ingredient lists cannot be used reliably to determine whether a product contains significant levels of iodine. 

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