Desalinated Water Linked to Cases of Iodine Deficiency

A study suggests and warns that relying on desalinated seawater as a population’s main source of drinking water can dramatically increase the prevalence of inadequate iodine intake, recommending individuals use iodized salt or other supplement and monitoring until an effective population-level solution has been found.

Iodine deficiency is a most important cause of preventable brain damage and mental deficiency. With surging population growth and water scarcity, seawater desalination is increasingly used to meet increased demand for water. Currently an estimated 300 million people worldwide rely on over 17,000 desalination plants in 150 countries for water.

On one hand "desalination is a blessing. However, we need to be mindful of unintended consequences," said Dr. Aron Troen, Hebrew University (Jerusalem, Israel), "Desalination removes minerals from the water and could conceivably diminish intake of minerals such as iodine that serve as essential micronutrients."

This initial (small but telling sample of 74 participants, including controls) study assessed the relationship between iodine intake and thyroid function in an area where drinking water is supplied from iodine-poor desalinated water. It found a surprisingly high prevalence of insufficient iodine intake and a strong association of thyroid dysfunction among adults with low iodine intake.

The study was conducted in the city of Ashkelon on the southern Mediterranean coast of Israel – a country with the highest percentage of desalinated water consumption in the world, where 5 desalination plants produce about 50% of its water. In collaboration with Dr. Dov Gefel and PhD student Yaniv Ovadia, Barzilai University Medical Center (Ashkelon, Israel), the researchers used an Iodine Food Frequency Questionnaire to model the effect of depleting iodine content in drinking water on the distribution of iodine intake. Thyroid function was rigorously assessed by clinical examination, ultrasound, and blood tests, including serum thyroglobulin (Tg) and autoimmune antibodies.

"Our estimated intake data are supported by significant associations of intake with a diagnosis of iodine deficiency disorders (IDD) and with elevated Tg, a putative biomarker of inadequate intake," said Dr. Troen, "The increasing reliance on desalination could [... raise] a nutritional and public health issue of a major global concern. This research supports the urgent need to probe the impact of desalinated water on thyroid health in Israel and elsewhere."

"Unlike magnesium, the solution is relatively straightforward - to iodize salt, provided there is legislation for routine population surveillance for iodine intake to ensure that salt iodization does not lead to excessive intake," said Dr. Troen. For those not allowed to take enough salt (e.g. due to high blood pressure), adding small amounts of supplement such as farmed seaweed flakes may help, though currently expensive.

The study, by Ovadia YS et al, was published online May 2016 in the journal Public Health Nutrition.

Related Links:
Hebrew University
Barzilai University Medical Center