Location: Methods and Application of Food Composition Laboratory
Project Number: 8040-10700-004-043-I
Project Type: Interagency Reimbursable Agreement
Start Date: Jul 17, 2026
End Date: Sep 30, 2028
Objective:
Dietary supplements and foods contain many functional constituents in addition to essential nutrients, but the contents of these constituents are not currently included in USDA’s FoodData Central (FDC), nor in the USDA/ODS Dietary Supplement Ingredient Database (DSID). These include iodine, nitrate and nitrite, purines, glucosinolates, and methylxanthines. The special interest databases (SIDs) target such dietary components of significant public health interest, which have been shown by substantial research to be additional critical components that have both beneficial and adverse effects on chronic degenerative disease risks. SIDs are necessary to fill knowledge gaps, support more accurate estimates of total exposures to these components in dietary intake and update pertinent dietary recommendations for health promotion and disease prevention. There are also substantial interests in the health effects of these components on part of the Food and Drug Administration, the Department of Defense, and the National Institutes of Health, USDA, as well as policy makers and consumers. The first research objective is to develop or update robust SIDs containing high-quality, up-to-date, and accurate compositional data for U.S.-based dietary supplements and foods that permit assessment of exposures to the components in the dietary intake patterns of the U.S. population. The second research objective is to investigate how food processing and cooking affect these food components in foods. The third research objective is to investigate the bioaccessibility of these compounds in foods and dietary supplements.
Approach:
The four special interest databases (SIDs), including nitrate and nitrite, purines, methylxanthines and iodine, will be developed or updated.
a. Nitrate and nitrite SID: The remaining raw and cooked food and dietary supplement samples will be analyzed by collaborators from The University of Oklahoma Health Campus (OUHS) using ozone chemiluminescence methodology. USDA will procure and process/cook additional foods and dietary supplements relevant to American dietary consumption patterns through existing USDA programs. Samples will be Selected Dietary Approaches to Stop Hypertension (DASH), frozen samples will also be analyzed by OUHS. The digestion and bioaccessibility of nitrate and nitrite in certain dietary supplements including soft gel, gummies and chews, will be assessed by using in vitro digestion model INFOGEST. Release 1.0 of the “USDA and ODS-NIH Database for the Nitrate and Nitrite Content of Foods” will be released on the MAFCL website pending FY 2026.
b. Purine SID: The remaining raw and cooked food and dietary supplement samples will be analyzed by the University of Florida Southeast Center for Integrated Metabolomics (SECIM) using hydrophilic interaction liquid chromatography coupled with tandem high-resolution mass spectrometry (HILIC-HRMS/MS). USDA will develop a sampling plan with ODS-NIH to evaluate a sub-selection of Dietary Approaches to Stop Hypertension (DASH) diet samples for purine content. DASH diet samples are currently stored at Virginia Tech and will be shipped to SECIM for analysis using previously described methods. Release 3.0 of the “USDA and ODS-NIH Database for the Purine Content of Foods” will be released on the MAFCL website in FY 2026.
c. Methylxanthine SID: A robust sampling plan comprised of detailed literature review, online market research, and comprehensive web-scraped data from popular websites will be developed to select dietary supplements. The HPLC based analytical method will be set up in MAFCL laboratory and validated with reference material(s) and QC materials. We expect to analyze and collect methylxanthine contents in approximately 100 dietary supplement samples, primarily focusing on the products containing high methylxanthine contents or commonly used by military personnels. Release 1.0 of the “USDA and ODS-NIH Database for the Methylxanthine Contents in Foods” will be released on the MAFCL website in FY 2027.
d. Iodine SID: USDA will review data generated to-date and will receive remaining results from the FDA Center for Food Safety and Applied Nutrition laboratory. New 2021-2022 FDA Total Diet Study (TDS) data will be included in the database pending its availability from the FDA. Release 5.0 of the “USDA, FDA, and ODS-NIH Database for the Iodine Content of Common Foods” will be released on the MAFCL website in FY 2026.