Nutritional Sciences Division, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK.
Br J Nutr. 2012 Apr;107(7):935-40. doi: 10.1017/S0007114511003059. Epub 2011 Jul 5.
Iodine is required for adequate thyroid hormone production, which is essential for brain development, particularly in the first trimester of pregnancy. Milk is the principal source of iodine in UK diets, and while small studies in Europe have shown organic milk to have a lower iodine concentration than conventional milk, no such study has been conducted in Britain. In view of the increasing popularity of organic milk in the UK, we aimed to compare the iodine concentration of retail organic and conventional milk and to evaluate regional influences in iodine levels. Samples of organic milk (n 92) and conventional milk (n 80), purchased from retail outlets in sixteen areas of the UK (southern England, Wales and Northern Ireland), were analysed for iodine using inductively coupled plasma MS. The region of origin of the milk was determined from information on the label. Organic milk was 42·1 % lower in iodine content than conventional milk (median iodine concentration 144·5 v. 249·5 ng/g; P < 0·001). There was no difference in the iodine concentration of either conventional or organic milk by area of purchase. However, a difference was seen in iodine concentration of organic milk by region of origin (P < 0·001). The lower iodine concentration of organic milk has public-health implications, particularly in view of emerging evidence of iodine deficiency in UK population sub-groups, including pregnant women. Individuals who choose organic milk should be aware that their iodine intake may be compromised and should ensure adequate iodine intake from alternative sources.
碘是甲状腺激素产生所必需的，而甲状腺激素对大脑发育至关重要，尤其是在妊娠的前三个月。在英国的饮食中，牛奶是碘的主要来源，虽然欧洲的一些小型研究表明有机牛奶的碘浓度低于传统牛奶，但在英国尚未进行过此类研究。鉴于有机牛奶在英国越来越受欢迎，我们旨在比较零售有机和传统牛奶的碘浓度，并评估碘水平的地区影响。从英国 16 个地区（英格兰南部、威尔士和北爱尔兰）的零售点购买了有机牛奶（n=92）和传统牛奶（n=80）样本，使用电感耦合等离子体质谱法（inductively coupled plasma MS）分析碘含量。牛奶的产地信息来自标签。有机牛奶的碘含量比传统牛奶低 42.1%（中位数碘浓度 144.5 v. 249.5ng/g；P<0.001）。购买地点的不同对传统或有机牛奶的碘浓度均无影响。然而，有机牛奶的碘浓度因产地的不同而存在差异（P<0.001）。有机牛奶的碘浓度较低对公共卫生有影响，特别是考虑到英国人群亚组中碘缺乏的新证据，包括孕妇。选择有机牛奶的人应该意识到他们的碘摄入量可能会受到影响，应确保从其他来源获得足够的碘。
