Iodine is an essential trace element of great importance in human nutrition. The
element is an essential part of the thyroid hormones triiodothyronine (T3) and thyroxin
(T4), which in turn are necessary for human growth and development. The best known
effect of iodine deficiency is endemic goiter. Goiter, meaning an enlarged thyroid, is
visual in the front of the neck where the thyroid gland lies. However, goiter is only
one manifestation of iodine deficiency and the wide spectrum of manifestations are
now commonly termed Iodine Deficiency Disorders (Hetzel, 1983; Hetzel and Dunn,
1989; Van der Haar et al., 1988). These disorders include endemic cretinism, infant
mortality, infertility, miscarriage, mental retardation, neuromuscular defects, and
dwarfism. Although iodine deficiency in theory could be readily and inexpensively
prevented, Iodine Deficiency Disorders continue to affect a large number of people
in the world. WHO estimates that Iodine Deficiency Disorders are currently a significant
public health problem in at least 118 countries (WHO/UNICEF/ICCIDD, 1993).
According to NRC (1989), the recommended allowance for adults of dietary iodine