Measurement of dietary exposure: a challenging problem which may be overcome thanks to metabolomics?

Abstract

The diet is an important environmental exposure, and its measurement is an essential component of much health-related research. However, conventional tools for measuring dietary exposure have significant limitations being subject to an unknown degree of misreporting and dependent upon food composition tables to allow estimation of intakes of energy, nutrients and non-nutrient food constituents. In addition, such tools may be inappropriate for use with certain groups of people. As an alternative approach, the recent techniques of metabolite profiling or fingerprinting, which allows simultaneous monitoring of multiple and dynamic components of biological fluids, may provide metabolic signals indicative of food intake. Samples can be analysed through numerous analytical platforms, followed by multivariate data analysis. In humans, metabolomics has been applied successfully in pharmacology, toxicology and medical screening, but nutritional metabolomics is still in its infancy. Biomarkers of a small number of specific foods and nutrients have been developed successfully but less targeted and more high-throughput methods, that do not need prior knowledge of which signals might be discriminatory, and which may allow a more global characterisation of dietary intake, remain to be tested. A proof a principle project (the MEDE Study) is currently underway in our laboratories to test the hypothesis that high-throughput, non-targeted metabolite fingerprinting using flow injection electrospray mass spectrometry can be applied to human biofluids (blood and urine) to characterise dietary exposure in humans.

Dietary exposure biomarker-lead discovery based on metabolomics analysis of urine samples

“…It was anticipated that the latter would provide a 'normalised' background against which differences in urine chemistry resulting from either previous habitual dietary intake prior to clinic visit or acute food intake during the test day would be detectable (12,14,20,25) . With effective protocols in place for volunteer management and urine sampling there was now an opportunity to determine whether changes in urine chemistry could reflect dietary exposure (11) . In an acute feeding 'proof of principle' study, urine samples were analysed from individuals participating in the MEtabolomics to characterise Dietary Exposure (MEDE) research programme (20) .…”

“…In an acute feeding 'proof of principle' study, urine samples were analysed from individuals participating in the MEtabolomics to characterise Dietary Exposure (MEDE) research programme (20) . As part of the MEDE project (11) , twenty-four healthy participants consumed a 'test' breakfast, in which the cereal component of a standardised breakfast was replaced by one of four foods of high public health importance, followed by the collection of postprandial urine samples for metabolome analysis (20,25) . Once candidate food biomarkers had been identified (25,26) there was then the opportunity to validate their potential usefulness to monitor habitual diet in the independent GrainMark study (http://www.ncl.ac.uk/afrd/ research/project/2287) (27) .…”

Comparisons of metabolic and physiological changes in rats following short term oral dosing with pesticides commonly found in food

“…These studies are clearly important but by focussing on overt toxicity they may miss subtle, low level effects on metabolism. Such metabolic changes may not directly reflect those seen at high levels of exposure (food toxicity) of individual pesticides since low levels of toxicant exposure may induce different changes than those induced by higher exposures but they have could be used to provide early warnings of possible toxicity prior to irreversible damage occurring; this would have great potential use in food safety assessment and regulation (Favé et al, 2009). …”

Metabolomics: Concept, methods and potential prospect in marine biology

“…The accuracy of this method is always affected by an unknown degree of misreporting. Metabolomics allows the simultaneous monitoring of multiple and dynamic components of biological fluids, so can be used to determine which metabolic signals are influenced by food intake [16]. The complexity of the metabolic response to the intake of different foods makes it challenging to study the relationship between the metabolome and patterns of food intake.…”