“…This approach has resulted in the identification of a number of putative biomarkers of specific foods and drinks such as citrus fruit (49,51,52) , cruciferous vegetables (53,54) , red meat (55,56) , coffee (57,58) , tea (59,60) , sugar-sweetened beverages (61) and wine (62) . A good example of a robust biomarker of citrus fruit is proline betaine, which was identified initially by Atkinson et al (52) and subsequently validated by independent research groups (49,51,63) . The biofluid used in all of these studies was urine; however, different metabolomic analytical strategies were applied to measure proline betaine, which included NMR and MS. One such study was performed by Heinzmann et al (49) , which involved eight volunteers consuming standardised meals over a 3 d period.…”