Iodine in food- and dietary supplement–composition databases

Abstract

The US Food and Drug Administration (FDA) and the Nutrient Data Laboratory (NDL) of the USDA Agricultural Research Service have worked independently on determining the iodine content of foods and dietary supplements and are now harmonizing their efforts. The objective of the current article is to describe the harmonization plan and the results of initial iodine analyses accomplished under that plan. For many years, the FDA's Total Diet Study (TDS) has measured iodine concentrations in selected foods collected in 4 regions of the country each year. For more than a decade, the NDL has collected and analyzed foods as part of the National Food and Nutrient Analysis Program; iodine analysis is now being added to the program. The NDL recently qualified a commercial laboratory to conduct iodine analysis of foods by an inductively coupled plasma mass spectrometry (ICP-MS) method. Co-analysis of a set of samples by the commercial laboratory using the ICP-MS method and by the FDA laboratory using its standard colorimetric method yielded comparable results. The FDA recently reviewed historical TDS data for trends in the iodine content of selected foods, and the NDL analyzed samples of a limited subset of those foods for iodine. The FDA and the NDL are working to combine their data on iodine in foods and to produce an online database that can be used for estimating iodine intake from foods in the US population. In addition, the NDL continues to analyze dietary supplements for iodine and, in collaboration with the NIH Office of Dietary Supplements, to publish the data online in the Dietary Supplement Ingredient Database. The goal is to provide, through these 2 harmonized databases and the continuing TDS focus on iodine, improved tools for estimating iodine intake in population studies.

Evaluation of dietary pattern in early pregnancy using the FIGO Nutrition Checklist compared to a food frequency questionnaire

“…7 Iodine is an important nutrient for fetal neurodevelopment in early pregnancy. 30 When using the FIGO Nutrition Checklist in pregnant women in Hong Kong it would therefore be beneficial to include an additional question that focuses on iodine-containing foods (e.g. seaweed, kelp, and the practice of iodized salt use).…”

Nutritional Gaps and Supplementation in the First 1000 Days

“…While iodine has not been included in the USDA's national nutrient databases, work is being done to use new analytical methods to measure the iodine content of foods that are expected to be contributors of iodine to the US diet [154]. Therefore, there are no reported intake values from large studies that can estimate national iodine intake.…”

Development of Databases on Iodine in Foods and Dietary Supplements

“…In the case of iodine, although the USDA has developed special databases for other nutrient-focused datasets, it was important to identify unique characteristics of iodine-contributing foods and dietary supplements. Other specific challenges related to database development included the need for methods for effective sampling and analysis of foods [ 19 ], and for statistical approaches that can accommodate variability in the iodine content of foods [ 58 ].…”

“…Also, enhanced quality control is achieved through close collaboration to utilize NIST standard reference materials and methods. Thus, existing data from the TDS will be used to enhance the national iodine dataset and also to set priorities for planned new or repeat analyses [ 19 ]. When planning the sampling of specific foods, it is critical to identify and acquire other relevant data that clarifies the distribution of iodine in the food supply (e.g., industry uses, agricultural production, sales, and other sources).…”

“…The need for improved data on the iodine content of foods and beverages has been noted by several expert committees [ 17 , 18 ] and has recently been reviewed in detail [ 19 ]. Also, iodine derived from dietary supplements must be included along with foods in order to accurately assess total intake; therefore, data are needed on the iodine content of supplements [ 20 ].…”