University of Nottingham, School of Biosciences, Division of Nutritional Sciences, Sutton Bonington, Loughborough, Leicestershire, LE12 5RD, United Kingdom.
University of Nottingham, School of Biosciences, Division of Agriculture and Environmental Sciences, Sutton Bonington, Loughborough, Leicestershire, LE12 5RD, United Kingdom.
J Trace Elem Med Biol. 2020 May;59:126453. doi: 10.1016/j.jtemb.2020.126453. Epub 2020 Jan 10.
Dairy products provide a crucial source of dietary iodine for the majority of the UK population, contributing approximately 30-40 % of daily intake. Fluctuations in the iodine content of purchased milk both seasonally and annually implies potential fragility of iodine supply likely through fluctuating supplementation practices in cow herds. We set out to establish the level of national variation in herds and identify factors which might impact milk iodine content.
Milk samples were obtained from 98 herds across the UK via the National Milk Laboratories in August and December 2016. Iodine concentration of samples was measured using ICP-MS. Milk samples and feed intake data were additionally taken from 22 cows from the University of Nottingham (UON) dairy herd.
There was considerable variation in milk iodine content from < 0.012 (Limit of Detection) to 1558 μg L, with a summer median of 197 μg L and winter median 297 μg L. Overall, winter values were higher than summer counterparts (P < 0.001) and this held true for samples taken from the North West (P = 0.002) and South West (P = 0.006) but not for other regions studied. Data from the UON herd showed a negative relationship between iodine content and milk yield (P = 0.03) and we found that milk iodine content varied considerably despite apparently similar iodine intakes.
Regional differences in milk iodine concentration between summer and winter suggests that feeding practices are far from uniform across the country. The negative association observed between iodine concentration and milk yield in UON samples, suggests that reduced summer values may be influenced by dilution in addition to seasonal differences in concentrate feed provision.
乳制品为英国大多数人口提供了重要的膳食碘来源，约占日常摄入量的 30-40%。购买牛奶的碘含量会随季节和年份波动，这意味着奶牛群的碘补充实践可能存在波动，从而导致碘供应不稳定。我们旨在确定全国牛群的碘含量差异，并确定可能影响牛奶碘含量的因素。
2016 年 8 月和 12 月，通过国家牛奶实验室，从英国各地的 98 个牛群中采集了牛奶样本。使用 ICP-MS 测量样本中的碘浓度。还从诺丁汉大学（UON）奶牛群的 22 头奶牛中采集了牛奶样本和饲料摄入量数据。
牛奶碘含量差异很大，范围从<0.012（检测限）到 1558μg/L，夏季中位数为 197μg/L，冬季中位数为 297μg/L。总体而言，冬季值高于夏季值（P<0.001），这种情况在西北地区（P=0.002）和西南地区（P=0.006）成立，但在其他研究地区则不然。来自 UON 牛群的数据显示，碘含量与牛奶产量之间存在负相关关系（P=0.03），我们发现，尽管碘摄入量似乎相似，但牛奶碘含量差异很大。
夏季和冬季牛奶碘浓度的区域差异表明，全国各地的饲养实践远非统一。UON 样本中观察到的碘浓度与牛奶产量之间的负相关关系表明，夏季值降低可能不仅受到季节性浓缩饲料供应差异的影响，还可能受到稀释的影响。
