Detecting Beer Intake by Unique Metabolite Patterns

Abstract

Evaluation of the health related effects of beer intake is hampered by the lack of accurate tools for assessing intakes (biomarkers). Therefore, we identified plasma and urine metabolites associated with recent beer intake by untargeted metabolomics and established a characteristic metabolite pattern representing raw materials and beer production as a qualitative biomarker of beer intake. In a randomized, crossover, single-blinded meal study (MSt1), 18 participants were given, one at a time, four different test beverages: strong, regular, and nonalcoholic beers and a soft drink. Four participants were assigned to have two additional beers (MSt2). In addition to plasma and urine samples, test beverages, wort, and hops extract were analyzed by UPLC-QTOF. A unique metabolite pattern reflecting beer metabolome, including metabolites derived from beer raw material (i.e., N-methyl tyramine sulfate and the sum of iso-α-acids and tricyclohumols) and the production process (i.e., pyro-glutamyl proline and 2-ethyl malate), was selected to establish a compliance biomarker model for detection of beer intake based on MSt1. The model predicted the MSt2 samples collected before and up to 12 h after beer intake correctly (AUC = 1). A biomarker model including four metabolites representing both beer raw materials and production steps provided a specific and accurate tool for measurement of beer consumption.

Validation of biomarkers of food intake—critical assessment of candidate biomarkers

“…For instance, during the cooking of meat, heterocyclic aromatic amines could be formed from creatinine, creatine, and amino acids at high temperature, which may be a biomarker of intensively cooked meat intake [ 25 ]. As an example of more complex markers based on food production, four different beer metabolites have been proposed as a combined marker of beer intake, two of them reflecting beer raw materials (hops and barley) and the other two reflecting the production processes (malting and fermentation), respectively [ 26 ]. If a candidate biomarker is highly specific (only minor interference is expected from other food sources), or unique for the food or food group in question, it is likely to have good plausibility.…”

“…For instance, highly oxidizable compounds such as beer humulones may degrade during storage of the beverage as well as during collection of urine samples voided into an oxygen-containing collection jar. Such compounds may only serve as BFIs when both the parent compound and the products are known and measured [ 26 ]. Other potential degradation pathways include pH instability and metabolism by enzymes or cells present in the preparation.…”

Combined Markers to Assess Meat Intake—Human Metabolomic Studies of Discovery and Validation

“…Combined biomarkers have been previously proposed to address the lack of specificity of individual biomarkers for particular foods. [5,19] For meat intake, carnosine was reported as an excellent predictor either alone or in combination with 1-and 3-methylhistidine. [6,49] In our study, however, carnosine misclassifies 16% of the samples and does not stand as a good predictor by itself.…”

Biomarkers of seaweed intake

“…The seven compounds are promising BFI candidates meeting several of the published validation criteria; however, we still lack information on their robustness, e.g., evidence from cross-sectional studies that these compounds are only observed after intake of seaweed and not after any other foods. In some cases, combinations of unspecific markers, which each overlap with a few other foods may provide very good specificity [33] as qualitative markers (e.g., seaweed intake yes/no) and such unspecific markers are therefore reasonable to retain even if the single compounds fail validation. The quantitative dose-response relationship of BFIs in human samples will also be needed to provide evidence for their use in quantification of seaweed intake.…”