Milk as a food source of iodine for human consumption in the Czech Republic

Abstract

The present study brings current information on providing dairy cows with the required iodine level after determination of its content in milk and on the relationship between its milk concentrations and iodine intake by human population. Iodine concentration in fresh cow milk from 226 farms covering 66 districts of the Czech Republic was assessed by the Sandell-Kolthoff Method. Average iodine concentration in a group of 226 bulk samples from distinct localities of the Czech Republic was 310.4 ± 347.0 μg I·l -1 and significant variations of iodine content in milk from different farms expressed by variation range < 10 to > 1000 μg I·l-1 was detected. The variations reflected marked differences in iodine saturation of dairy cows. Average milk iodine concentration is twice and a half the findings detected before supplementation which was initiated between the years 1997-1999 and is higher than the current European standard. Deep iodine deficiency in fodder, non-corrected by feed supplements, was found in 4.0% of milk samples with the values < 20 μg I·l-1. Iodine milk concentrations above 500 μg I·l-1 were detected in 16.8% farms. After determination of iodine concentrations in the diets fed to dairy cows it is recommendable to regulate the offer of supplements containing iodine according to the physiological requirements of the animals, their production and environmental conditions. General monitoring of iodine concentrations in fresh milk followed by immediate providing the farmers with the results is essential. It is necessary to consider significantly higher average iodine concentrations in milk purchased by milk processing plants from the farms in the year 2003 (323.7 ± 364.3 μg I·l-1) when iodine intakes through the basketfuls of foodstuffs by consumers are evaluated.