Crucial role of data quality evaluation in constructing food composition databases using literature sources

Authors: Wu, Xianli; HEYDORN, KATHERINE - University Of Maryland; PANDEY, DEEPESH - University Of Maryland; PEHRSSON, PAMELA - Retired ARS Employee; HAYS, FRANK - University Of Oklahoma Health Sciences Center; WAMBOGO, EDWINA - National Institutes Of Health (NIH); DWYER, JOHANNA - National Institutes Of Health (NIH); Weng, Yiqun; WAMBOGO, EDWINA - National Institutes Of Health (NIH); DWYER, JOHANNA - National Institutes Of Health (NIH)

Submitted to: The American Journal of Clinical Nutrition
Publication Type: Other
Publication Acceptance Date: 5/14/2026
Publication Date: 6/11/2026
Citation: Wu, X., Heydorn, K., Pandey, D., Pehrsson, P., Hays, F., Wambogo, E., Dwyer, J., Weng, Y., Wambogo, E., Dwyer, J. 2026. Crucial role of data quality evaluation in constructing food composition databases using literature sources. The American Journal of Clinical Nutrition. https://doi.org/10.1016/j.ajcnut.2026.101357.
DOI: https://doi.org/10.1016/j.ajcnut.2026.101357

Interpretive Summary: This Letter to the Editor expresses concerns regarding the data presented in a recently published article by Zhong et al. on nitrate and nitrite food composition and the derived database in American Journal of Clinical Nutrition (Nitrate and nitrite food composition database: an update and extensive deep dive. AJCN, 2025 121: 1124–1136). Our primary concern involves the extreme and physiologically implausible ranges of nitrate reported in the paper. Some biologically or analytically impossible values were reported in this paper. For example, maximum concentration of nitrate in raw spinach was reported as 28,867.49 mg/kg, which is equivalent to approximately 38.0% of the dry weight. Given that all data in the paper were extracted from published literature, these findings suggest that the authors did not perform data quality evaluation or screen for implausible values. Moreover, because all subsequent analyses in the paper relied on these extracted values, the inclusion of evidently incorrect data may compromise the integrity of the study’s conclusions. Nitrate and nitrite values have raised controversies due to their reported positive and negative effects to human health. To better interpret exposure, and potential links to beneficial and harmful health effects, the accurate measurement and consistent value verification of nitrate and nitrite in foods as well as in dietary supplements and water is crucial.

Technical Abstract: This Letter to the Editor expresses concerns regarding the data presented in a recently published article by Zhong et al. on nitrate and nitrite food composition and the derived database in American Journal of Clinical Nutrition (Nitrate and nitrite food composition database: an update and extensive deep dive. AJCN, 2025 121: 1124–1136). Our primary concern involves the extreme and physiologically implausible ranges of nitrate reported in the paper. Some biologically or analytically impossible values were reported in this paper. For example, maximum concentration of nitrate in raw spinach was reported as 28,867.49 mg/kg, which is equivalent to approximately 38.0% of the dry weight. Given that all data in the paper were extracted from published literature, these findings suggest that the authors did not perform data quality evaluation or screen for implausible values. Moreover, because all subsequent analyses in the paper relied on these extracted values, the inclusion of evidently incorrect data may compromise the integrity of the study’s conclusions. Nitrate and nitrite values have raised controversies due to their reported positive and negative effects to human health. To better interpret exposure, and potential links to beneficial and harmful health effects, the accurate measurement and consistent value verification of nitrate and nitrite in foods as well as in dietary supplements and water is crucial.