Average iodine content

Various analytical techniques for the determination of different levels of total iodine or iodine species in foodstuffs and related materials are presently available. They differ in principles, equipment needed, detection limits, reliability, i.e., accuracy and precision of results, the ease of performance, sample throughput, and analysis cost. The choice of the most appropriate method largely depends on the purpose of the analysis, e.g., whether it concerns routine monitoring and/or screening or whether delicate certification of a foodstuff reference material is to be carried out. Obviously, one of the decisive parameters is whether the method s detection limit is sufficiently low for the given purpose. For this reason, it appears useful to give the typical iodine levels in various foods to facilitate the choice of the appropriate method(s). Table 2.5 lists the average iodine content of foods (fresh and dry basis), which was adapted from the data reported by Koutras et al. (1985). 

Table 2.5 Average iodine content of foods ((ig kg urine ((xg ...

Table 13.3 Average iodine content of drinking water in Denmark (/xg/i)...

Norwegian milk and dairy products also contain relatively high amounts of iodine. Analysis of the iodine concentration in milk (i.e., low-fat milk, 1.5% fat) showed seasonal variation. The average iodine content of low-fat... 

No differences were found between the average iodine content within the same season for different types of milk, e.g., skimmed milk versus full-fat milk (Dahl et al.,... 

In a study on thyroid glands derived from 107 rats, e.ssentially similar iodine values (mean, 18 mg %) were observed by Sankaran (1931) for animals between 20 and 150 days of age. A higher average iodine content of 66 mg % was reported by Remington et at. (1936-1937) in assays of 131 glands from animals aged 30 days to 1 year, but in accordance with Sanka-ran s investigation, no correlation was noted between age and the thyroidal iodine level. 

The average oil content of commercial com hybrids planted in the com belt has declined over the last 50 years from 4.8-5.0% to 4.4%.52 The apparent cause of this decline has been widespread use of one or two high yielding, low oil content corn inbreds. At the same time, the iodine value of com oil has increased from 122-124 to 128-130, equivalent to a linoleic acid content increase from 55% to 60%. This change is apparently associated with the decline in oil content.53... 

Figure 6 Proposed structures for iodine contents from (a) to (d) average I/C2H2 (c) structure (d) is for undoped trans-Pj...

The ioxilan carbonate particles were prepared as a contrast medium by solvent extract/ evaporation method. The preparation involved emulsification of a methylene chloride solution of the carbonate, removal of solvent, and washing and sizing the particles. The iodine content of the particles was 45%. The average diameter of the ioxilan carbonate particles was 1.1 pm, 95%of them ranging from 0.6 and 2.0 jam. Electron microscopy showed the particle surface to be smooth, and the particles showed practically no aggregation when mixed with rat plasma. The LDgo value for the ioxilan carbonate particles was 1.4 g I/kg for... 

The analysis of iodine contents of several feeds and foodstuffs grown on German soils from the Triassic formation (distance from seaside 400 km) shows that vegetation on Bunter, Muschelkalk and Keuper weathering soils have, on average, a 28% lower iodine concentration (Table 9-4.2). This reflects the distance to the seaside and the lower iodine levels in sediments of the Triassic formation. 

On average, iodine intake satisfies the normative requirement when the iodine content of intrathyroidal and extrathyroidal tissues exceeds those listed in Table 9-4.10 (Groppel et al. 1988). Normally, the iodine levels in these tissues are higher. 

Figure 13.10 Correlation between iodine content of tap water in 41 towns in Denmark and the average 24 h urinary iodine excretion in young men in each town. Source Pedersen et al., (1999) reproduced with permission.

Notes-. Weight = overall weight of the menu and weights of the meal constituents 1/100 g menu = iodine content in 100 g of the menu (average) l/menu = overall iodine content of fhe selecfed menu. 

It can be observed from Table 44.2 that the variation in iodine content is markedly higher among individual urine samples than the variation in average annual urinary iodine concentration. In comparison, CV% is 2.4 times larger for spot urine iodine concentration than for the average annual iodine content. This difference is 2.7 for interquartile range (IQR) (Andersen et al, 2001). 

The iodine concentration in foods of all types varies considerably due to a number of factors, such as soil composition, animal breeding, climate, and other environmental variables. Moreover, the amount of iodine from each food depends on the source, preparation, processing and volume consumed. The iodine value for a food represents an average and does not consider the wide variations in the iodine content of the food hence some values, such as those from food composition tables, used in the evaluation of iodine intakes are likely to be subject to error. In addition, the use of food composition tables may be considered inappropriate to reasonably estimate iodine intake in groups of individuals consuming unconventional foods not listed, or inconsistently listed, in such tables. 

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