Table 2.
Possible scoring scheme for legume intake biomarker validity
| Food item | Metabolites | Biofluid locations | Questions | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | |||
| Soy | Genistein | Urine | Y | Y | Y | N | N | Y | Y | U |
| Plasma/serum | Y | Y | Y | N | N | Y | Y | U | ||
| Dihydrogenistein | Urine | N | U | U | N | N | U | Y | U | |
| Plasma/serum | N | U | U | N | N | U | Y | U | ||
| Dihydrodaidzein | Urine | N | U | U | N | N | U | Y | U | |
| Plasma/serum | N | U | Y | N | N | U | Y | U | ||
| Enterodiol | Urine | N | U | U | N | N | U | Y | U | |
| Plasma/serum | N | U | U | N | N | U | Y | U | ||
| Enterolactone | Urine | N | U | U | N | N | U | Y | U | |
| Plasma/serum | N | U | U | N | N | U | Y | U | ||
| Matairesinol | Urine | N | U | U | N | N | U | Y | U | |
| Plasma/serum | N | U | U | N | N | U | Y | U | ||
| Daidzein | Urine | Y | Y | Y | N | N | Y | Y | U | |
| Plasma/serum | Y | Y | Y | N | N | Y | Y | U | ||
| Equol | Urine | N | U | Y | N | N | U | Y | U | |
| Plasma/serum | N | U | Y | N | N | U | Y | U | ||
| O-desmethylangolensin | Urine | N | U | U | N | N | U | Y | U | |
| Plasma/serum | N | U | Y | N | N | U | Y | U | ||
| Glycitein | Urine | Y | U | Y | N | N | U | Y | U | |
| Plasma/serum | Y | U | Y | N | N | U | Y | U | ||
| Pulses | Kaempferol | Urine | N | U | Y | U | U | U | Y | U |
| Dimethylamine | Urine | N | U | U | U | U | U | Y | U | |
| Glutamine | Urine | N | U | U | U | U | U | Y | U | |
| 3-Methylhistidine | Urine | N | U | U | U | U | Y | Y | U | |
| Trigonelline | Urine | N | Y | U | U | U | U | N | U | |
| Plasma/serum | N | U | U | N | U | U | Y | U | ||
| Pipecolic acid | Plasma/serum | N | U | U | Y | U | U | Y | U | |
| Indolepropionate | Plasma/serum | U | U | U | N | U | U | U | U | |
| S-Methylcysteine | Plasma/serum | U | U | U | Y | U | U | U | U | |
| N-Acetyl-ornithine | Plasma/serum | U | U | U | N | U | U | U | U | |
Possible answers are Y (yes), N (No), or U (unknown or uncertain)
Questions1. Is the marker compound plausible as a specific biomarker of food intake for the food or food group (chemical/biological plausibility)?2. Is there a dose-response relationship at relevant intake levels of the targeted food (quantitative aspect)?3. Is the biomarker kinetics described adequately to make a wise choice of sample type, frequency and time window (time-response)?4. Has the marker been shown to be robust after intake of complex meals reflecting dietary habits of the targeted population (robustness)?5. Has the marker been shown to compare well with other markers or questionnaire data for the same food/food group (reliability)?6. Is the marker chemically and biologically stable during biospecimen collection and storage, making measurements reliable and feasible (stability)?7. Are analytical variability (CV%), accuracy, sensitivity and specificity known as adequate for at least one reported analytical method (analytical performance)?8. Has the analysis been successfully reproduced in another laboratory (reproducibility)?