Iodine concentration in milk and human nutrition: A review

The aim of the review was to provide information about the importance of iodine in human nutrition and to review milk as an important source of iodine, and also to summarize the main factors affecting iodine concentration in milk. Iodine is an essential element for the thyroid gland function and synthesis of thyroid hormones, which regulate key processes of metabolism, brain development and growth. Therefore, it is important to ensure adequate, neither deficient nor excessive, intake of this element in animal nutrition, but more importantly in the nutrition of humans. Milk and dairy products are very valuable sources of iodine. However, its concentration in milk is very variable, as it is affected by many different factors - iodine intake in feed, antinutritional factors, iodine species (forms) used for feeding, animal keeping, farm management and possibly also milk yield. Additionally, milk iodine concentration is also affected by teat dipping with iodine disinfection, and by milk processing (e.g. skimming and heat treatment). All these aforementioned factors may possibly play their role in improving human nutrition, especially the nutrition of pregnant, lactating women, and people on a low-salt diet who are the most vulnerable to insufficient iodine intake.