Table 2.
Evaluation of the validity of the identified candidate biomarkers of food intake for liquorice
| Metabolite | Bio fluid | Q1 | Q2 | Q3 | Q4 | Q5 | Q6 | Q7 | Q8 | Q9 | Sum | References |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Candidate liquorice biomarkers of food intake | ||||||||||||
| 18-glycyrrhetic acid | Plasma | U | U | Y | U | Y | N | U | Y | N | 3 | [50, 51, 55] |
| Serum | U | U | Y | U | Y | N | U | Y | N | 3 | [54] | |
| Blood | U | U | Y | U | N | N | U | Y | N | 2 | [53] | |
| Urine | U | Y | Y | U | Y | N | U | Y | N | 4 | [51–53] | |
| 3β-monoglucuronyl-18β-glycyrrhetinic acid | Urine | U | U | N | U | Y | N | U | Y | N | 2 | [19] |
| Glabridin | Plasma | U | U | U | U | N | N | U | N | N | 0 | [56] |
Y yes, N no, U unknown
Q1: Is the marker compound plausible as a specific BFI for the food or food group (chemical/biological plausibility)?
Q2: Is there a dose-response relationship at relevant intake levels of the targeted food (quantitative aspect)?
Q3: Is the single-meal time-response relationship described adequately to make a wise choice of sample type and time window (single-dose kinetics)?
Q4: Is the biomarker kinetics for repeated intakes of the food/food group described adequately providing the frequency of sampling needed to assess habitual intake (e.g. cumulative aspects)?
Q5: Has the marker been shown to be robust after intake of complex meals reflecting dietary habits of the targeted population (robustness)?
Q6: Has the marker been shown to compare well with other markers or questionnaire data for the same food/food group (reliability)?
Q7: Is the marker chemically and biologically stable during bio specimen collection and storage, making measurements reliable and feasible?
Q8: Are analytical variability (CV%), accuracy, sensitivity and specificity known as adequate for at least one reported analytical method?
Q9: Has the analysis been successfully reproduced in another laboratory (reproducibility)?