The importance of iodine – are you drinking enough milk?

Ensuring the safety of the food we eat is of paramount importance. Iodine is an essential element naturally found in some foods. Insufficient amounts of iodine in the diet results in low levels of thyroid hormones, which are responsible for regulation of metabolism.

In pregnant women and infants iodine is of particular importance as it plays a critical role in brain development. The primary sources of iodine for most people are milk and dairy products but due to increases in dairy intolerance and changes in diet, milk-products are being increasingly substituted for non-milk alternatives.

To identify the impact that such dietary changes might have on iodine levels across the population, an understanding of the levels of iodine naturally present in milk is necessary. This includes the effects of seasonal variations or fat content and any processing effects of pasteurisation which might reduce the iodine content. These variations have been investigated by the Nutrition Innovation Centre for Food and Health (NICHE), Ulster University, with milk samples collected over a 12-month period. However, these differences needed to be measured accurately in order to properly determine the influence different conditions have on iodine content.

As part of the UK’s National Measurement Laboratory (NML) role, scientists at LGC have developed a high accuracy quantitative method (inductively-coupled plasma mass spectrometry) for the analysis of iodine in milk and milk-products to support the regulation on iodine levels in infant formulas. Using this expertise, we were able to support the work being done at Ulster University, providing the analytical capability required to determine the levels of iodine in milk under a variety of conditions.

Of the collaboration, Maria O’Kane, lead author on the paper, said: “LGC facilitated my visit to the laboratory in Teddington and enabled me to undertake analysis of the milk samples collected using high accuracy ICP-MS. The expert staff at LGC supported my learning and enabled me to develop a greater knowledge and understanding of ICP-MS analysis.”

The findings were recently published in the Journal of Nutrition, where Maria concluded that consuming additional cow milk can significantly increase the amount of iodine observed in the urine of women of childbearing age.

This work will help our understanding of current iodine intake and support future research in this area and clearly demonstrates the impact the UK’s National Measurement Laboratory (NML) can have on real-world problems, protecting human health and ensuring the safety of our food.