A newly released study in the 'Molecules' Journal shows that the higher purity profile of vitamin K2 as MK7 correlates with an enhanced stability in formulation. This finding could help explain title discrepancies found in finished products analysed in the worldwide market in the last few years (Molecules 2019, 24(5), 829; https://doi.org/10.3390/molecules24050829)
These discrepancies are at the heart of the debate on MK7 stability between major MK7 ingredient producers and of finished dietary supplements manufacturers.
The study compared the purity profiles of different raw materials and the results were related to stability assay in normal (12months/25°C/60%RH) and accelerated conditions (six months/40°C/75% RH) in order to test their performance in presence of different common excipients. In particular, two naturally-fermented MK7 and a synthetic one, all commercially available, were used.
All the active ingredients were independently formulated with minerals largely used on the market in combination with MK7. Finally, experimental observations were complemented by comparison of the actual/nominal content of MK7 in different formulations commercially available on the international markets, where the producers state on their labels the source of MK7 used to manufacture the finished products.
Data highlighted that different purity profiles corresponded to different stability profiles, where pure products generally showed the highest stability. Moreover, the study explained that patterns of instability could be associated with types of MK7 characterised by different purity profiles.
In particular, the multiplicity of chromatographic impurities was frequently observed and consistently associated with lower content of the all-trans isomer (isomeric purity) or with an underestimation of the assay, despite the fact that an overage of the supplement formula is a common practice to minimize the risk of degradation and, consequently, of a lower assay of the formula. Moreover, the study has highlighted that, though it is very likely that menaquinones show a very high thermal stability while they may be degraded following exposure to UV radiation and alkaline compound, the destabilising effect of the minerals was not identical in the presence of different MK7. The synthetic MK7 showed the lowest purity profile characterised by 23 species accounting for 5.67% of the unknown components.
The study also reinforce the concept that MK7 materials, which equally comply to minimal assay and composition characteristics as detailed by the official USP quality standard for dietary ingredients, may be different in terms of their purity profiles due to the presence of cis isomers and other impurities.
Silvia Pisoni, marketing manager of the Gnosis by Lesaffre commented: “VitaMK7 is one of the naturally fermented MK7 ingredients tested in the study, with positive results - in line with our current campaign of information about quality and stability. We really believe this work can help all players and actors of 'vitamin k2 as MK7' market to shed a light on this amazing ingredient and on its chemical behaviour."
