Seasonal and regional variations of the iodine content in milk from Federation of Bosnia and Herzegovina

Abstract

The aim of this study was to determine the iodine concentrations in raw cow’s milk produced in Federation of Bosnia and Herzegovina (B&H) and to evaluate the milk iodine contribution to the iodine intake in the B&H population. Milk samples (n=139) were taken from five regions during the spring, summer and winter season. Iodine concentrations were determined by the inductively coupled plasma mass spectrometry (ICP-MS) method. The mean (± standard deviation) milk iodine concentration was 60.9±67.5 μg/kg and ranged from 4.4 to 378.7 μg/kg. Winter milk had higher iodine content (84.0±88.2 μg/kg) than the spring (45.3±46.7 μg/kg) and summer milk (51.3±51.0 μg/kg), although two of five investigated regions did not follow this tendency and had the similar milk iodine content in all three seasons. Very low iodine concentrations (<20 μg/kg) were found in 41 milk samples from four regions indicating extensive iodine deficiency in dairy cows. Milk samples from the north-east of the country had much more iodine than samples from other regions in all seasons with no values below 20 μg/kg. With the current average intake of 0.4 L milk per day, the milk contributes with 20 % of the recommended iodine intake for humans, ranging from 6 % to 72 % depending on the season of the year and the region of the country. The results indicate the need for iodine supplementation of animal diets, as well as for increased milk consumption in human population.