Bioavailability of menaquinone-7 in milk formulation. Comparison of different solubilization techniques

Abstract

Menaquinone-7 (MK-7) is a type of vitamin K of fermentative origin that plays a key role in cardiovascular and bone health as a cofactor of gamma-glutamyl carboxylase enabling the activation of several vitamin K-dependent proteins, particularly at the extrahepatic level. Despite its proven biological efficacy and outstanding bioavailability over other dietary menaquinones, its presence in food is marginal, especially in the Western diet. Dairy products are a major dietary source of menaquinones of minor biological relevance for human health and constitute optimal carriers due to their lipid content. Dairy fortification with MK-7 represents an attractive formulative strategy, also for the high calcium and vitamin D content that may act synergistically in promoting vitamin K-dependent functions. However, limited solubility of MK-7 in aqueous solution may limit its use and affect its bioavailability in vivo. The present study compares the bioavailability of MK-7 in enriched 1%-fat milk either as a direct powder solution or a pre-emulsified dispersion. Bioavailability data show that formulation strategies strongly affect the bioavailability of MK-7 and that the results are greatly improved when it is prepared as an oil–water emulsion.