Dihydrovitamin K1 in oils and margarines

In the present study the vitamin K1 and 2′,3′-dihydrovitamin K1 contents of several crude vegetable oils, partially hydrogenated oils used as raw materials in the margarine industry and margarines were analysed with a high-performance liquid chromatographic (HPLC) method. Prior to quantification by reverse-phase HPLC with an electrochemical (EC) detector, hexane extracts of samples were purified by straight-phase semipreparative HPLC. Menaquinone-4 (MK-4) was used as an internal standard. All hydrogenated oils (rapeseed, soybean and mixture of rapeseed and palm) contained considerable amounts of 2′,3′-dihydrovitamin K1, which accounted for approximately 60% of the sum of 2′,3′-dihydrovitamin K1 and vitamin K1; however, among the margarines analysed 2′,3′-dihydrovitamin K1 was found only in hard margarines meant for the baking industry. The proportion of 2′,3′-dihydrovitamin K1 in these products was 25% of the total. The appearance of 2′,3′-dihydrovitamin K1 among the samples analysed correlated with that of trans fatty acids. During recent years the Finnish margarine industry has focused on reducing the amount of trans fatty acids in soft margarines. It was concluded that because of these changes in the manufacturing process, 2′,3′-dihydrovitamin K1 plays no significant role in vitamin K nutrition in Finland.