History of iodised salt

Overview


Iodised salt (AmE: iodized salt), table salt mixed with a minute amount of sodium iodide or iodate, is used to help reduce the chance of iodine deficiency in humans. Iodine deficiency commonly leads to thyroid gland problems, specifically endemic goiter. Endemic goiter is a disease characterized by a swelling of the thyroid gland, usually resulting in a bulbous protrusion on the neck. While only tiny quantities of iodine are required in a diet to prevent goiter, the United States Food and Drug Administration recommends (21 CFR 101.9 (c)(8)(iv)) 150 microgrammes of iodine per day for both men and women, and there are many places around the world where natural levels of iodine in the soil are low and the iodine is not taken up by vegetables.

Today, iodized salt is more common in the United States, Australia and New Zealand than in Britain.

United States
In the U.S. in the early 20th century, goiter was especially prevalent in the region around the Great Lakes and the Pacific Northwest. Goiter began receiving serious attention as a result of the World War I draft pointing to the problem in Northern Michigan and Wisconsin. At this time, many men were disqualified from military service as a result of the public health problem. This raised questions beyond the ability of these men to serve in the war. Many asked: if they could not do this, how useful were they in everyday civilian life?

David Murray Cowie pioneered the salt iodation process in America. A professor of pediatrics at the University of Michigan, Cowie was concerned about the widespread problem of goiter in Michigan (nicknamed the "goiter belt" of America). Aware of the Swiss process of adding sodium iodide or potassium iodide to table and cooking salt, Cowie decided that a simple way to address the problem of iodine deficiency would be to merely implement the Swiss solution in America. He had noted that adding iodine to aquatic environments in the Pacific Northwest seemed to decrease the incidence of goiter among fish species. Public opinion also supported his effort in that "important discoveries of vitamins and their roles in food nutrition" were happening during the period. Cowie appealed to the Michigan State Medical Society, a "productive group which concerned itself with the search for answers to difficult medical questions pertaining to the health of the state's residents".

Incorporating iodine into a regular diet would not be an easy process; the salt producers of America had to be persuaded to incorporate sodium iodide into their production process. It was difficult to prove that people who consumed iodized salt were better protected from simple goiter, a difficulty that contributed to resistance to the movement. Cowie and the Michigan State Medical Society turned to the Michigan Salt Producer's Association in 1923. Soon, an iodized salt committee was formed. After several months of meetings and deliberations with physicians and educators, the Executive Council of the Michigan State Medical Society gave Cowie the authority to endorse and implement the production of iodized salt, and the Michigan salt producers agreed to begin producing iodized table salt with labels reading "contains .01 per cent sodium iodide".

On May 1, 1924, iodized salt by Diamond Crystal Salt, Mulkey Salt, Inland Delray Salt, Michigan Salt Works, and Ruggles and Rademaker appeared on Michigan grocers' shelves. By the fall of 1924, Morton Salt Company began distributing iodized salt nationally.

Cowie's efforts to improve the public health environment necessitated broad cooperation. Cowie gained support from the medical board and market support from the Michigan Salt Producers Association, and with this scientific backing, the general public accepted the change. Through this process, we have an early example of an optimal default being created in the field of public health. Cowie's efforts also added a new focus on prevention as well as the advancement and improvement of social and industrial lives as it became more prevalent during the Progressive era, rather than on merely curing diseases. It was also highlighted by a larger focus on vitamins and in general the possibility of supplementing foods as a way to solve health problems.