Methods and Application of Food Composition Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, USA.
Biochemistry Department, Virginia Tech, Blacksburg, VA 24061, USA.
Nutrients. 2023 Jul 8;15(14):3077. doi: 10.3390/nu15143077.
In a previous study, large variability in iodine content was found among samples of store brand retail milk at a single time point in a sampling taken from 24 nationwide U.S. locations for the USDA FoodData Central database, but the sampling plan was not designed to detect differences among locations. This follow-up study was carried out to evaluate iodine levels in retail milk across the U.S. over time. Milk samples (2% fat) were collected bimonthly in fourteen locations for one year and analyzed in duplicate. Control materials were used to support accuracy of results and ensure precision across analytical batches. The overall mean and standard error (SE) for iodine concentration were 82.5 (7.0) µg/240 mL serving, which was comparable to the previous national mean [85.0 (5.5) µg/240 mL]. A similar wide range among individual samples was detected (27.9-282 µg/240 mL). For some locations, the mean iodine concentration differed significantly from others, and differed from the national average by amounts ranging from -47 µg to +37 µg per serving. The between-sample range within location was large for some (up to 229 µg/serving) and minimal for others (as little as 13.2 µg/serving). These findings suggest iodine intake from some retail milk supplies could be over- or underestimated relative to the national average, even if the national average is suitable for population-wide intake estimates.
在之前的一项研究中，在美国全国 24 个地点进行的一次抽样调查中，单一时间点的商店品牌零售牛奶样本中发现碘含量存在很大差异，但是该抽样计划并不是为了检测地点之间的差异而设计的。本后续研究旨在评估美国各地零售牛奶中的碘含量随时间的变化情况。在一年的时间里，每隔两个月在 14 个地点采集 2%脂肪的牛奶样本，并进行重复分析。使用控制材料来支持结果的准确性，并确保整个分析批之间的精密度。碘浓度的总体平均值和标准误差（SE）为 82.5（7.0）µg/240mL 份，与之前的全国平均值[85.0（5.5）µg/240mL]相当。在个别样本中也检测到类似的广泛差异（27.9-282µg/240mL）。对于某些地点，碘浓度的平均值与其他地点有显著差异，与全国平均值的差异幅度在每份 47µg 至 37µg 之间。某些地点的样本内差异范围较大（高达 229µg/份），而其他地点的差异范围较小（低至 13.2µg/份）。这些发现表明，即使全国平均水平适合于全人群的摄入量估计，某些零售牛奶供应的碘摄入量相对于全国平均水平可能会过高或过低。
