Dietary Sources.

Reference from the joint report of FAO/WHO expert consultation on Human Vitamins and Minerals verbatim.

Dietary sources

Koutras, D.A., Matovinovic, J. & Vought, R. 1985. The ecology of iodine. In: Stanbury

J.B., Hetzel B.S. (eds). Endemic goitre and cretinism, iodine nutrition in health and disease. p. 185-95.New York: Wiley Eastern Limited.

The iodine content of food depends on the iodine content of the soil in which it is grown. The iodine present in the upper crust of earth is leached by glaciation and repeated flooding and is carried to the sea. Sea water is, therefore, a rich source of iodine. The seaweed located near coral reefs has an inherent biologic capacity to concentrate iodine from the sea. The reef fish which thrive on seaweed are rich in iodine. 

Thus, a population consuming seaweed and reef fish has a high intake of iodine, as the case in Japan. The amount of iodine intake by the Japanese is in the range of 2–3 mg/day. In several areas of Asia, Africa, Latin America, and parts of Europe, iodine intake varies from 20 to 80 μg/day. In the United States and Canada and some parts of Europe, the intake is around 500 μg/day. The average iodine content of foods (fresh and dry basis) as reported by Koutras et al. is given in Table 35.

The iodine content of food varies with geographic location because there is a large variation in the iodine content of the inorganic world (Table 36). Thus, the average iodine content of foods shown in Table 35 can not be used universally for estimating iodine intake.

Recommended intake

US National Research Council. 1989. Recommended dietary allowances. 10th edition. Iodine Food and Nutrition Board. P. 213-217. Washington D.C., National Academy Press Publication.

The daily intake of iodine recommended by the National Research Council of the US National Academy of Sciences in 1989 was 40 μg/day for young infants (0–6 months), 50 μg/day for older infants (6–12 months), 60–100 μg/day for children (1–10 years), and 150 μg/day for adolescents and adults (5). These values approximate 7.5 μg/kg/day for age 0–12 months, 5.4 μg/kg/day for age 1–10 years, and 2 μg/kg/day for adolescents and adults. These amounts are proposed to allow normal T4 production without stressing the thyroid iodide trapping mechanism or raising TSH levels.