Nitrate and nitrite food composition database: an update and extensive deep dive.

Background: Growing evidence suggests that health outcomes of dietary nitrate and nitrite intake are food source dependent. Robust evaluations in dietary studies necessitate a comprehensive and current food composition database of nitrate/nitrite content, along with variation based on country or region of origin, calendar year, growing season, and cooking method.

Objectives: The objectives of this study were to update the previous animal- and plant-based food nitrate/nitrite databases and investigate effects of cooking methods, seasonal and geographic variations, and longitudinal changes on nitrate and nitrite content to guide application of the database in observational and clinical studies.

Methods: Food nitrate/nitrite composition data was acquired from an extensive worldwide data collation. The animal- and plant-based food nitrate/nitrite databases were combined and substantially expanded. An in-depth data stratification and comparison were performed to explore retention factors of nitrate/nitrite, seasonal differences in vegetable nitrate, geographic variations, and the temporal change in food nitrate/nitrite content over 30 years.

Results: The aggregated database has >150,000 nitrate and nitrite values for 823 foods, being 5+ times their original size. Nitrite content in plant foods is presented for the first time, being ≤12.27 mg/kg of fresh weight. Retention factors of 55.00 (39.59-65.56) % (median (interquartile range)) and 279.53 (179.53-386.89) % are now suggested for boiled and fried plant foods, respectively, with a factor of 1.0 for other cooking methods. Significant seasonal variations in plant nitrate and geographic differences in both plant- and animal-based foods are identified, whereas several leafy vegetables show declining nitrate content over 30 years, and longitudinal changes in nitrate and nitrite in animal foods are minor. An objective language-model-assisted data extraction pipeline was established that accommodates regional differences in nitrate/nitrite data reporting.

Conclusions: The newly developed database and automated nitrate/nitrite calculator will facilitate future nutritional health studies to estimate dietary nitrate/nitrite exposure more accurately and efficiently and determine the resulting health implications.