Text: Antoine Menuisier

Dr Iodine and Mr Salt

Health authorities insist on the urgent need to reduce salt intake, but deficiencies of iodine – a vital element contained in salt – are emerging.


Picture: François C., age 28, from the Pyrenees region, was listed as having a goitre in Benedict Augustin Morel’s Treatise on Degeneration (Traité des dégénérescences published in 1857).

Health is a major issue in the apocalyptic film “World War Z”. In the film, Brad Pitt’s character sets out to save humanity, which is in danger of extinction due to a fearsome virus. He pieces together an insane but spectacular plot to kill the deadly virus with another pathogen that is slightly less lethal for humans. And his plan works. Here, the situation is in absolutely no way comparable, except that the concept, in its boldness, is the same. A vector potentially harmful to human health if ingested in large amounts, i.e. salt, is used to supply the body with iodine, an element essential to its development and thyroid hormone synthesis.

The Swiss no longer consume enough iodine. “Daily dietary intake of iodine is 150 micrograms (µg) for adults and 200 to 250 µg for pregnant women,” says Murielle Bochud, chief physician at the University Institute of Social and Preventive Medicine (IUMSP) at Lausanne University Hospital (CHUV) and full professor at the Faculty of Biology and Medicine at the University of Lausanne. “In a nationwide survey on salt intake conducted from January 2010 to April 2012 and coordinated by the IUMSP and the nephrology department at the CHUV led by Professor Michel Burnier on behalf of the Swiss Federal Office of Public Health (FOPH), we found cases of iodine deficiency in Swiss women over age 15: 14% – i.e. one out of seven – had urinary iodine excretions of less than 95 µg over a 24-hour period.”

The population should be encouraged to consume iodine without increasing their salt intake.

These are worrying figures because iodine deficiency can cause developmental delays and intellectual disabilities (see inset). So what’s happening? Do Swiss women use less iodised salt in their cooking? Or are they eating more pre-cooked meals made without iodine-enriched salt?

In any case, they do not seem to be eating less salt. Averaging 9.1 grams per inhabitant per day, with men eating more salt than women, salt intake is too high. The World Health Organization (WHO) recommends average salt intake of less than 5 grams per day. In Switzerland, the Swiss Federal Food Safety and Veterinary Office (FSVO) sets the target at 6 grams per day.

Iodine is an essential trace element found in its natural state in seafood and dairy products. However, excessive salt intake increases the risk of developing cardiovascular diseases. The population, especially women of childbearing age, should be encouraged to consume iodine without increasing their salt intake.

“The main problem is processed food. Pre-cooked meals account for 95% of salt intake, while only 5% is from table salt,” says Vincent Dudler, head of the Risk Assessment Division at the FSVO. “Due to the freedom of trade and industry, Swiss producers are not required to add iodine to the salt used in preparing processed foods, such as bread or dried meat, but they can do it without being forced to.”

The Swiss Federal Food Commission (COFA) issued a recommendation for all Swiss sodium chloride producers to increase iodine content per kilogram of table salt produced in Switzerland from 20 to 25 milligrams. The Vaud-based saltworks company La Saline de Bex, which extracts and sells salt, and other manufacturers voluntarily complied. “We increased the iodine content per kilogram of sodium
chloride,” says Loïc Jaunin, head of quality, safety and environment at La Saline de Bex, “which involves spraying the salt crystals with a potassium iodide solution.” The process is not financed by the government and has a significant impact on the price of salt. We need to consume more “Dr Iodine”, that precious trace element found in saltwater fish and eggs, while watching our intake of
“Mr Salt”. ⁄

An age-old problem

Iodine is found in high concentrations in seawater. Switzerland’s soil, far from any coastline, contains little iodine, and the Swiss people have historically shown symptoms of iodine deficiency. The Swiss federal authorities introduced iodised salt in 1922 to fight the human developmental problems caused by the scarcity of the trace element. “Iodine deficiency has long been the cause of congenital cretinism, a form of dwarfism associated with mental retardation triggered by a deficiency of thyroid hormones,” says Murielle Bochud from the IUMSP. The expression “cretin of the Alps” originally referred to inhabitants of the Swiss, French and Italian Alps. The disease was particularly prevalent there, as inhabitants lived far from the coast. Individuals with goiter could also be found in the region. This condition causes an enlargement of the thyroid gland, which is often caused by iodine deficiency.



​Stocking up on iodine

Iodine plays a key role in a number of the organism’s metabolic reactions. It occurs naturally in various types of foods:


The sea contains vast amounts of iodine, and the food provided by the sea is generally the best source of this trace element. The most iodine-rich foods include haddock, salmon, cod and prawns.

Dairy products

Milk and dairy products provide about one-third of the daily intake requirement and are the main dietary source of iodine in western countries. This is due to the use of iodine-rich fertilisers used on grazing land for dairy cattle and antiseptic products containing iodine to prevent the development of bacteria in the treatment chain.


Eggs, along with seaweed, are a valuable source of iodine for vegetarians. Containing 9.3 micrograms of iodine per 100 grams, eggs provide about 33% of the daily iodine requirement.