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 µg 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.