Food Iodine Content Table compiled from international databases Tabela do Conteúdo de Iodo de Alimentos compilada de bancos de dados internacionais

In Brazil, there are no data on the iodine content of foods, making it difficult for the population to assess their consumption of iodine. Such information is necessary for public policies aimed at establishing nutritional goals. The objective this article is to construct a table of the iodine content of foods. For the construction of the table, databases from 14 countries were used. The foods used were those listed in the 2008-2009 Household Budget Survey, except those containing added salt, and the doubts about whether or not the food was submitted to any kind of preparation. The compilation of international databases of iodine content resulted in 266 foods, which were grouped into 15 groups. Iodine was also quantified by food group and iodized salt. Data were presented as median, minimum, and maximum. A broad variation in the iodine content of foods was found


A B S T R A C T
In Brazil, there are no data on the iodine content of foods, making it difficult for the population to assess their consumption of iodine. Such information is necessary for public policies aimed at establishing nutritional goals. The objective this article is to construct a table of the iodine content of foods. For the construction of the table, databases from 14 countries were used. The foods used were those listed in the 2008-2009 Household Budget Survey, except those containing added salt, and the doubts about whether or not the food was submitted to any kind of preparation. The compilation of international databases of iodine content resulted in 266 foods, which were grouped into 15 groups. Iodine was also quantified by food group and iodized salt. Data were presented as median, minimum, and maximum. A broad variation in the iodine content of foods was found between countries and inter-and intra-food groups. Those with the highest content were fish and seafood, and dairy products. Regarding salt iodization, these countries followed the recommendation of the World Health Organization, except for Spain, Norway and Turkey. The Food Iodine Content Table can be a useful tool for assessing iodine intake, being important in research on nutritional status, food guidance, and public health programs.

I N T R O D U C T I O N
Iodine is essential in the synthesis of thyroid hormones, necessary for growth, development, and metabolism in the human body. Its inadequate intake can lead to thyroid dysfunction, causing a series of adverse health conditions, such as hypertrophy of the thyroid gland (goiter), cretinism in children (severe and irreversible mental retardation), deafness and congenital anomalies, cognitive changes (such as decreased learning capacity), and infant mortality [1][2][3]. Iodine deficiency is considered the main cause of preventable mental retardation [4][5][6]. On the other hand, it is observed that excessive iodine consumption can increase the risk of induced hyperthyroidism [7].
About 20% of the world population is at risk of iodine deficiency, being more prevalent in developing countries, although its mild or moderate form is found in industrialized countries [8]. Still, iodine deficiency is found in one third of the world population, in the groups of pregnant women, children, and healthy non-pregnant adults [9].
There was a reduction in the prevalence of iodine deficiency in the world, with the following chronological order: in 2003, fifty-four countries were considered iodine deficient, in 2011, they were reduced to thirty-two [10]. This reduction was due to the salt iodization programs and better monitoring of iodine deficiency [11]. In Brazil, due to the high consumption of added salt, and processed and ultra-processed foods, salt iodination was changed from 20 to 60 ppm to 15 to 45 ppm [2].
Differences in the iodine content of foods, together with different eating habits, are decisive factors in the iodine nutritional status in the population [12]. The distribution of iodine in the world is uneven, since the geographical characteristics interfere with its content in food [2,13]. Glaciation, flooding, and erosion remove iodine from the soil and thus it is mainly found in seas and oceans, which justifies the higher content in foods of marine origin (algae, fish, and shellfish). Geochemical data demonstrate that iodine deficiency in food is related to the low concentration of iodine in the environment, especially in groundwater, which is the main source of water for the population [14].
In Brazil, there is no data on the iodine content of national foods, making it difficult to assess iodine consumption by the population. This information is necessary so that public policies can establish nutritional goals. In this sense, the construction of the Food Iodine Content Table (FICT) becomes an important pillar in the provision of subsidies for the assessment of iodine intake.

M E T H O D S
The construction of the Food Iodine Content Table (FICT) is part of the Projeto Multicêntrico de Deficiência de Iodo: Brazil (EMDI, Multicentric Iodine Deficiency Project). The EMDI project aims to assess the magnitude of the deficiency and the factors associated with the iodine nutritional status in Brazilian pregnant women, nursing mothers, and infants.
For the construction of the Food Iodine Content Table (FICT), the review article entitled "Development of databases on iodine in foods in dietary supplements" was used [15]. It contains a list of all countries that had a database of iodine content in food. Of the 24 countries, only 14 made their databases available for consultation. Chart 1 shows the 14 countries consulted and their documents or databases.   [30]. The option was made to search for foods that did not contain added salt since, in different countries, the levels of iodine added to salt vary. In addition, foods that raised doubts regarding the existence of preparation or not (e.g. cappuccino, instant coffee) were excluded. The diagram below illustrates the stages of construction of the FICT (Figure 1).
To build the FICT, international iodine content databases were compiled, resulting in 266 foods, which were grouped into 15 food groups as described in the POF: Cereals and legumes; Tuberous vegetables; Flours, starches, and pasta; Coconuts, chestnuts, and walnuts; Leafy vegetables, fruits, and others; Fruits; Sugars and pastries; Condiments; Meat and offal; Fish and seafood; Poultry and eggs; Dairy products; Non-alcoholic drinks and infusions; Oils and fats; and Miscellaneous [30]. The iodine contents in salt were compiled separately due to the divergence of iodine levels in different countries, as they adopt specific legislation for salt enrichment.
The data were described as median (minimum and maximum), expressed in µg of iodine per 100g of food in the FICT. For foods whose data were obtained from only one country, the figures were presented only in absolute terms.

R E S U L T S
The Table 1 shows the Food Iodine Content Table compiled from international databases and the specification of countries that provided data on iodine content. The number of foods and the median (minimum and maximum) iodine content per food group are shown in Table 2. The fish and seafood group had the highest iodine levels. In addition to this, the groups of dairy products and tuberous vegetables stood out in relation to the highest iodine contents among food groups. Regarding the iodine content in iodized salt, a large variation was found, up to 10 times more, in different countries (Table 3).  Note: * The references to access the international iodine content tables can be seen in Chart 1.

D I S C U S S I O N
A great variation was found in the iodine content of foods among countries, as shown in the Food Iodine Content Table (FICT) compiled from the international databases (Table 1). These findings can be justified by the interference of geographical characteristics in the iodine content, since it is proportional to its content in each country's soil and water [13]. This variability is also related to animal and plant production practices and the type of food processing [15]. It is worth mentioning that, in this study, prepared and processed/ultra-processed foods with added salt were not listed. Note: * The references to access the international iodine content tables can be seen in Chart 1. ** Value not found.
The high iodine content found in the fish and seafood group may be related to the fact that iodine is naturally found in seas and oceans, accumulating in marine organisms [14,31]. Meanwhile, the expressive iodine content of the dairy group can be explained by the fact that iodine is used to fortify food for cows, or as an antiseptic for udders and containers [4]. If the animals are fed with plants that grew in soil with low in iodine, the content of this element may be poor as well [1]. This fact may justify the great variability in iodine content within this group. Another group where iodine contents also stood out was the tuberous vegetables group, probably because iodine is deposited in the terrestrial environment by rain, from the evaporation of marine water [31].
Regarding iodized salt, the large variation in iodine content is possibly related to differences in the amount of iodine added in the process of salt enrichment [15,32], since the WHO suggests that the average amount of iodine added to the salt should be based on the estimated consumption of salt by the population, with 14 to 65mg kg -1 of iodine in the salt (1400 to 6500µg 100 g -1 ), for an estimated salt intake from 14g/day to 3g/day, respectively [8]. As observed in the databases, Spain, Norway, and Turkey did not comply with this recommendation. In Brazil, the reduction of the salt iodization levels from 2000-6000µg 100g -1 to 1500-4500µg 100g -1 occurred due to the large consumption of added salt and ultra-processed and processed foods [2].
The main limitation of the FICT, for its use in Brazil, is the fact that its data are compiled from other countries, not from food produced in Brazil. However, because it is intercontinental data, this discrepancy may have been minimized. Considering the scarcity of these data in Brazil and the importance of iodine analysis in dietary assessment, the FICT becomes an indispensable instrument for assessing iodine consumption.

C O N C L U S I O N
Information on the iodine content in foods is essential for assessing their intake, being important in research of nutritional status, dietary guidance, and public health programs. Therefore, the FICT, compiled from international databases, becomes an essential tool for this purpose, since there are no data produced in Brazil on the iodine content in foods.

C O N T R I B U T O R S
RCRM MILAGRES, participated in the design, analysis, and interpretation of data, review and approval of the final version of the article. ECG SOUZA and MSL DUARTE participated in the conception, design, analysis, and interpretation of data, review and approval of the final version. MCG PELUZIO and SC FRANCESCHINI participated in the conception, design, analysis, and interpretation of data.