Background: Gastric fluid plays a key role in food digestion and drug dissolution, therefore, the amount of gastric fluid present in a fasted state may influence subsequent digestion and drug delivery. We aimed to describe intra- and interindividual variation in fasted gastric content volume (FGCV) and to determine the association with age, sex, and body size characteristics. Methods: Data from 24 MRI studies measuring FGCV in healthy, mostly young individuals after an overnight fast were pooled. Analysis included 366 participants with a total of 870 measurements. Linear mixed model analysis was performed to calculate intra- and interindividual variability and to assess the effects of age, sex, weight, height, weight*height as a proxy for body size, and body mass index (BMI). Results: FGCV ranged from 0 to 156 mL, with a mean (SD) value of 33 mL (25 mL). The overall coefficient of variation within the study population was 75.6%, interindividual SD was 15 mL, and the intraindividual SD was 19 mL. Age, weight, height, weight*height, and BMI had no effect on FGCV. Women had lower volumes compared to men (MD: -6 mL), when corrected for the aforementioned factors. Conclusion: FGCV is highly variable, with higher intraindividual compared to interindividual variability, indicating that FGCV is subject to day-to-day and within-day variation and is not a stable personal characteristic. This highlights the importance of considering FGCV when studying digestion and drug dissolution. Exact implications remain to be studied.

DNL has received an unrestricted educational grant from B Braun and speakers honoraria from Nestle, Abbott and Corza for unrelated work. RS has received research grants from Zespri International and Sanofi and speakers fees from Ardelyx, Menarini & Ferrer. All other authors declare no conflict of interest.

This study did not receive any funding

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Ethical statements of all the datasets included in the analysis in this manuscript: Alyami, et al. (2019): The study University of Nottingham, Medical School Research Ethics gave ethical approval for this work (F12072016). Camps, et al. (2021): The Medical Ethical Committee of Wageningen gave ethical approval for this work. Camps, et al. (2018): The Medical Ethical Committee of Wageningen gave ethical approval for this work (NL48059.081.14). ClinicalTrials.gov NCT05575687: The Medical Ethical Committee of Wageningen gave ethical approval for this work ClinicalTrials.gov NCT05854407: The Medical Ethical Committee of Wageningen gave ethical approval for this work. Coletta, et al. (2016): The study University of Nottingham, Medical School Research Ethics gave ethical approval for this work. Deng, et al. (2023): The Medical Ethical Committee of Wageningen gave ethical approval for this work (NL74166.081.20). Freitas, et al. (2022): The ethics committee Lyon Sud-Est IV gave ethical approval for this work (A 17 347). Grimm, et al. (2018): The ethical review board of the Ernst Moritz Arndt University of Greifswald gave ethical approval for this work (BB 079/14). Hussein, et al. (2015): The study University of Nottingham, Medical School Research Ethics gave ethical approval for this work. Juovonen, et al. (2015): The Essex 1 Research Ethics Committee gave ethical approval for this work. Krishnasamy, et al. (2020): The study University of Nottingham, Medical School Research Ethics gave ethical approval for this work. Lobo, et al. (2009): The study University of Nottingham, Medical School Research Ethics gave ethical approval for this work. Marciani, et al. (2010): The local ethics committee gave ethical approval for this work. Marciani, et al. (2012): The study University of Nottingham, Medical School Research Ethics gave ethical approval for this work. Marciani, et al. (2013): The study University of Nottingham, Medical School Research Ethics gave ethical approval for this work. Marciani, et al. (2015): The study University of Nottingham, Medical School Research Ethics gave ethical approval for this work. Mudie, et al. (2014): The local Medical School Research Ethics Committee gave ethical approval for this work. Murray, et al. (2015): The local Medical School Research Ethics Committee gave ethical approval for this work. Roelofs, Tjoelker, et al. (2024): The Medical Ethical Committee of Wageningen gave ethical approval for this work. Roelofs, van Eijnatten, et al. (2024): The Medical Ethical Committee Arnhem-Nijmegen gave ethical approval for this work. Trialsearch.who.int NL8137: The Medical Ethical Committee Arnhem-Nijmegen gave ethical approval for this work. van Eijnatten, Camps, et al. (2023): The Medical Ethical Committee of Wageningen gave ethical approval for this work (NL66536.081.18)). van Eijnatten, Roelofs, et al. (2023): The Medical Ethical Committee of Wageningen gave ethical approval for this work.

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All data produced in the present study are available upon reasonable request to the authors