ArticleNutrients2019
Determination of Urinary Caffeine Metabolites as Biomarkers for Drug Metabolic Enzyme Activities.
Article in Nutrients, 2019. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 8 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
8 citing papers in PubMed, 13 citations in OpenAlex.
- Association between dietary intake and urinary concentrations of caffeine and caffeine metabolites and elevated serum prostate-specific antigen (PSA) among men at risk for prostate cancer.Cancer causes & control : CCC · 2025Article
- Characterization the microbial diversity and metabolites of four varieties of Dry-Cured ham in western Yunnan of China.Food chemistry: X · 2024Article
- Caffeine and Its Antioxidant Properties-It Is All about Dose and Source.International journal of molecular sciences · 2022Review
- Evaluation of CYP1A2 activity: Relationship between the endogenous urinary 6-hydroxymelatonin to melatonin ratio and paraxanthine to caffeine ratio in dried blood spots.Clinical and translational science · 2022Article
- Candidate Proficiency Test Chemicals to Address Industrial Chemical Applicability Domains forFrontiers in toxicology · 2022Review
- Metabolomic signatures in elite cyclists: differential characterization of a seeming normal endocrine status regarding three serum hormones.Metabolomics : Official journal of the Metabolomic Society · 2021Article
- Caffeine metabolites are associated with different forms of caffeine supplementation and with perceived exertion during endurance exercise.Biology of sport · 2021Article
- Effects of Caffeine and Coffee on Human Functioning.Nutrients · 2020Article
Corrections and comments
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Authors and funding
7 authors at 2 institutions in 2 countries.
Funding
Abstract
Caffeine is commonly taken via the daily dietary consumption of caffeine-containing foods. The absorbed caffeine is metabolized to yield various metabolites by drug-metabolizing enzymes, and measuring the levels of each caffeine metabolite can provide useful information for evaluating the phenotypes of those enzymes. In this study, the urinary concentrations of caffeine and its 13 metabolites were determined, and the phenotypes of drug metabolic enzymes were investigated based on the caffeine metabolite ratios. Human urine samples were pretreated using solid phase extraction, and caffeine and its metabolites were analyzed using liquid chromatography-tandem mass spectrometry. Based on the urinary caffeine metabolite concentrations, the caffeine metabolite ratios were calculated for six human subjects at specified time points after caffeine intake. Variations in urinary metabolite levels among individuals and time points were reported. In addition, the resultant enzyme activities showed different patterns, depending on the metabolite ratio equations applied. However, some data presented a constant metabolite ratio range, irrespective of time points, even at pre-dose. This suggests the possibility of urinary caffeine metabolite analysis for routine clinical examination. These findings show that urinary caffeine and the metabolite analysis would be useful in evaluating metabolic phenotypes for personalized medicine.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.