Abstract
Benzoic acid is widely used as a preservative in food products and is detoxified in humans through glycine conjugation. Different viewpoints prevail on the physiological significance of the glycine conjugation reaction and concerns have been raised on potential public health consequences following uncontrolled benzoic acid ingestion. We performed a metabolomics study which used commercial benzoic acid containing flavored water as vehicle for designed interventions, and report here on the controlled consumption of the benzoic acid by 21 cases across 6 time points for a total of 126 time points. Metabolomics data from urinary samples analyzed by nuclear magnetic resonance spectroscopy were generated in a time-dependent cross-over study. We used ANOVA-simultaneous component analysis (ASCA), repeated measures analysis of variance (RM-ANOVA) and unfolded principal component analysis (unfolded PCA) to supplement conventional statistical methods to uncover fully the metabolic perturbations due to the xenobiotic intervention, encapsulated in the metabolomics tensor (three-dimensional matrices having cases, spectral areas and time as axes). Identification of the biologically important metabolites by the novel combination of statistical methods proved the power of this approach for metabolomics studies having complex data structures in general. The study disclosed a high degree of inter-individual variation in detoxification of the xenobiotic and revealed metabolic information, indicating that detoxification of benzoic acid through glycine conjugation to hippuric acid does not indicate glycine depletion, but is supplemented by ample glycine regeneration. The observations lend support to the view of maintenance of glycine homeostasis during detoxification. The study indicates also that time-dependent metabolomics investigations, using designed interventions, provide a way of interpreting the variation induced by the different factors of a designed experiment–an approach with potential to advance significantly our understanding of normal and pathophysiological perturbations of endogenous or exogenous origin.
Highlights
Applications of metabolomics to intervention or challenge studies greatly enhance the holistic understanding of the effects of consumed substances on metabolic pathways [1, 2]
We present the experimental design for an intervention study which includes the complex aspects mentioned above
All results were based on the 344 1H-NMR profiled bins for 21 cases, following the elimination of two outlier batches, across the 6 time points
Summary
Applications of metabolomics to intervention or challenge studies greatly enhance the holistic understanding of the effects of consumed substances on metabolic pathways [1, 2]. Data sets from intervention studies are, complex, as these investigations aspire to measure multiple metabolites in a biofluid, obtained from several experimental subjects, collected at different points in time and subjected to interventions from different consumed substances. These studies call for methods of data analysis designed for longitudinal (time-dependent), multi-subject (data from several experimental participants), multi-group (intervention studies) and multivariate data [3, 4]. We present the full experimental design of the intervention study, but focus on the contribution from the biotransformation response by presenting the outcomes of vehicle consumption only. The results on the alcohol and NAD interventions will be published in a separate paper
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
