The Saline Solution
Most people know that goiter is the result of a low level of iodine in the diet. Fewer may be aware that pregnant women who are iodine-deficient may deliver an infant with a severe mental and physical handicap known as cretinism. Far less widely recognized is the more recent finding that iodine deficiency is also responsible for millions of cases of subtle brain damage, which affects learning and work abilities.
Iodine deficiency disorders (IDD) are uncommon in the United States, where nutritional levels of iodine are sufficient, partly because iodine has been added to most table salt. But it is estimated that 1.5 billion people living in 118 countries--mostly developing nations--are iodine-deficient.
Researchers have found that in these countries, a mother’s iodine deficiency during pregnancy is responsible for a much larger number of people with impaired intellectual abilities than previously thought.
The implications of the lost intellectual ability are especially profound in countries where economic development is hampered by disease and dwindling economies. One study has shown that a moderate lack of iodine in young people can reduce intelligence quotients 10 to 15 points.
International health agencies say IDD is the leading preventable cause of mental retardation in the world. They estimate the current toll to be 655 million people affected by goiter, 5.7 million by cretinism and 43 million by some degree of IDD-related brain damage that impairs learning and work skills.
Many countries lack iodine because it has been leached out of the soil by flooding or irrigation, and food crops are deficient.
UNICEF, the World Bank and the World Health Organization have launched a worldwide program to eliminate IDD by iodizing table salt in places where it is not now done. Studies have shown that doing so will provide everybody with sufficient iodine to eliminate the physical and mental toll now being taken.
Iodine is needed to make thyroid hormones, which are essential for normal development of the brain and nervous system and control many chemical processes in other parts of the body. People who lack iodine typically are slow learners and tend to be physically sluggish. This is of special interest in developing countries, where research has established that insufficient iodine lowers resistance to malaria and infectious diseases and make children more likely to succumb to those diseases.
A study in Zaire has shown that when iodine was given to women who then became pregnant, their newborns weighed more and had double the survival rate of iodine-deficient babies.
The decision to iodize the world’s salt was reached in 1990, when leaders of 154 nations met in New York at the World Summit on Children and were persuaded by health officials to undertake a children’s health agenda that included eliminating IDD.
In 1990, 46 of the 118 countries at risk of IDD had national salt iodization programs. Today the number is 83 and most of the rest are in the process.
In Africa, virtually all edible salt is now iodized in Algeria, Cameroon, Eritrea, Kenya, Namibia, Nigeria, South Africa, Zambia and Zimbabwe. Sufficient progress also has been made in Bangladesh, Bhutan, Pakistan, India and Peru.
Nevertheless, agencies still face plenty of challenges, social as well as medical. In the West African nation of Ghana, for example, passage of an iodization bill has been delayed by red tape for many months. As a consequence, salt producers in Ghana are exporting 70% of their iodized salt to countries where iodization has already been mandated.
If the Ghana legislation is passed this year, officials hope to have 90% of the salt iodized by mid-1997. The president of the salt producers’ association in Ghana says: “We want to make this program successful,” but in August there was no assurance the bill would pass this session.
In nearby Guinea, a 1993 survey revealed that 70% of adults had goiter and 2% of the children of goitrous mothers were cretins. Fifty-five percent of schoolchildren have early-stage goiter, thus marking them as victims of possible mental impairments. “Solving the problem involves the cooperation of the whole social structure . . . and educating [people] that iodine is an essential element,” said the physician in charge of the project in Ghana’s hard-hit region.
Recognizing the seriousness of the situation, health workers in Guinea have distributed thousands of capsules containing iodine and oil. The capsules provided a quick source of iodine that can reverse goiter and provide protection to fetuses by giving women enough of the essential elements to last a year or two. This is seen as an emergency procedure because it is far more costly than iodizing the salt and is not a permanent solution.
The effort to iodize salt worldwide is the latest chapter in humanity’s age-old relationship with salt. Sodium and chloride are the two components of salt. As with iodine, both are important in the chemical balance and performance of cells. Their concentration in blood reflects their concentrations in the sea, from which land animals originated. Their balance is maintained by the kidneys.
In contrast to modern-day medical warnings about the health risks of too much salt, acquiring enough salt for the needs of a settlement or a nation appears to have been a major concern since humans evolved. According to historian Robert P. Multhauf, man and animal meat-eaters who live by hunting and fishing satisfy their salt needs by diet alone, but plant-eating animals and man need additional salt.
Rice-eating people around the world, most of whom live in warm countries, consume more salt (15 to 20 grams per day) than other people because rice itself is very low in salt. People in temperate zones consume only 5 to 8 grams a day, according to the International Council for Control of Iodine Deficiency Disorders, which provides the scientific information for the iodization effort.
The idea of iodizing salt was pioneered in the United States, several European countries and Australia and New Zealand in the early 1900s. Most of the world’s iodine is imported from Japan and Chile.
The first large-scale trials of iodized salt in this country were undertaken in Ohio between 1916 and 1920. Impressed by the preventive and therapeutic results, a massive program was launched in Michigan, which was a part of the “goiter belt” that included the area around the Great Lakes. Adding iodine to the salt reduced the prevalence of goiter among Michigan school children from 39% in 1924 to 9% in 1929. Today fewer than 5% of Americans have goiter.
