Quantification of vitamin K (phylloquinone and menaquinones 4-10) in various shellfish.

Vitamin K exists naturally in foods as phylloquinone (vitamin K₁, PK) and as a range of menaquinones (vitamin K₂, MK). There is scarce information on the occurrence and distribution of PK and MK in dietary sources, particularly in seafood. This study aimed to comprehensively analyse the contents of vitamin K_1, dihydro-K₁, and MK-4 to MK-10 in various species, tissue types and processing degrees of shellfish. Additionally, seasonal differences in the vitamin K content of blue mussels (Mytilus edulis) were explored. Most shellfish products had low contents of total vitamin K (< 10 µg/100 g). The highest content of total vitamin K was found in the hepatopancreas of snow crab (170 µg/100 g), the brown meat of brown crab (35 µg/100 g), pre-packaged blue mussels (20 µg/100 g), stuffed brown crab shells (15 µg/100 g) and blue mussels in brine (12 µg/100 g). In general, the hepatopancreas of crustaceans contained considerably higher contents of vitamin K than their white meat counterparts. MK contributed most to total vitamin K contents, whereas most shellfish products contained low contents of PK, thus making only a minor contribution to the adequate intake established for adults. No statistically significant differences were observed in PK and MK contents of blue mussels sampled during spring v. late summer (P < 0·005). Nevertheless, a non-significant trend of increasing vitamin K content was observed towards the autumn months. This study presents novel vitamin K data for shellfish, an unexplored food group, and adds to the scarce vitamin K composition data worldwide.