Identification of cis/trans isomers of menaquinone-7 in food as exemplified by dietary supplements

For the first time, the cis/trans isomer content of menaquinone-7 in food products has been identified and marked. A novel method of marking isomers of vitamin K2MK-7 in dietary supplements was developed and validated. Five different isomers of cis/trans vitamin K2MK-7 were identified. Identification of cis/trans isomers was performed by HRMS-QTOF, whereas their quantities were determined by using CAD and DAD detectors. In the majority of cases, the content of biologically active all trans vitamin K2MK-7 was below its declared content. The content of all trans K2MK-7 was in the range between 5.5 and 49 mu g in pills. In one of the studied supplements, this vitamin was not found, regardless of the claim on the product label. The content of cis/trans isomers in certain dietary supplements exceeded the content of all trans K2MK-7 by up to 3.7 times.