A model to secure a stable iodine concentration in milk

Abstract

BackgroundDairy products account for approximately 60% of the iodine intake in the Norwegian population. The iodine concentration in cow's milk varies considerably, depending on feeding practices, season, and amount of iodine and rapeseed products in cow fodder. The variation in iodine in milk affects the risk of iodine deficiency or excess in the population.ObjectiveThe first goal of this study was to develop a model to predict the iodine concentration in milk based on the concentration of iodine and rapeseed or glucosinolate in feed, as a tool to securing stable iodine concentration in milk. A second aim was to estimate the impact of different iodine levels in milk on iodine nutrition in the Norwegian population.DesignTwo models were developed on the basis of results from eight published and two unpublished studies from the past 20 years. The models were based on different iodine concentrations in the fodder combined with either glucosinolate (Model 1) or rapeseed cake/meal (Model 2). To illustrate the impact of different iodine concentrations in milk on iodine intake, we simulated the iodine contribution from dairy products in different population groups based on food intake data in the most recent dietary surveys in Norway.ResultsThe models developed could predict iodine concentration in milk. Cross-validation showed good fit and confirmed the explanatory power of the models. Our calculations showed that dairy products with current iodine level in milk (200 µg/kg) cover 68, 49, 108 and 56% of the daily iodine requirements for men, women, 2-year-old children, and pregnant women, respectively.ConclusionsSecuring a stable level of iodine in milk by adjusting iodine concentration in different cow feeds is thus important for preventing excess intake in small children and iodine deficiency in pregnant and non-pregnant women.

Iodine Deficiency in a Study Population of Norwegian Pregnant Women—Results from the Little in Norway Study (LiN)

“…However, the total iodine intake is still not in accordance with the recommendation. Analysis of the iodine content in milk and dairy products in Norway in 2000 [ 33 ] showed a seasonal variation, but more recent analyses show that this variation has been less pronounced in recent years [ 34 , 35 ]. The urine samples in the present study were collected in 2011–12.…”

Suboptimal Iodine Status among Pregnant Women in the Oslo Area, Norway

“…In all calculations, iodine concentrations reported in the Norwegian Food Composition Table [ 16 ] were used for all items except milk and egg. We applied 13 µg/100 g for milk and 30 µg/100 g for eggs, as analytical results for iodine concentration in these items were lower than the values in the food composition table [ 17 , 18 ]. For estimating 24-h iodine intake in the main study and the habitual iodine intake in the sub-study, we applied recipes to derive an iodine concentration in composite dishes and for averaging concentrations from different fish species.…”

Suboptimal Iodine Concentration in Breastmilk and Inadequate Iodine Intake among Lactating Women in Norway

“…The iodine concentrations reported in the Norwegian Food Composition Table [ 26 ] were used for all items except milk and egg. We applied 13 µg/100 g for milk and 30 µg/100 g for eggs, as analytical results for iodine concentration in these items were lower than the values in the food composition table [ 27 , 28 ]. We applied recipes for deriving iodine concentration in composite dishes and for averaging concentrations from different fish species.…”