Cholecalciferol and 25-Hydroxycholecalciferol Contents in Fish and Fish Products

The cholecalciferol and 25-hyroxycholecalciferol contents in 39 fish and fish product items were analyzed by a high-performance liquid chromatographic (HPLC) method. The method included saponification and extraction, purification using semipreparative straight-phase HPLC, and quantification by reverse-phase HPLC. The quantification of cholecalciferol and 25-hyroxycholecalciferol was based on the internal standard method. Ergocalciferol was used as the internal standard for cholecalciferol and 25-hyroxyergoacalciferol was used as the internal standard for 25-hyroxycholecalciferol. Cholecalciferol was the predominant compound. The cholecalciferol contents in fish and fish products ranged from under the limit of determination (0.2 μg/100 g) to 47.7 μg/100 g fresh weight. Very small amounts of 25-hyroxycholecalciferol (near the limit of determination, 0.1 μg/100 g) were found only in some salmonids. Much variation was found in the cholecalciferol contents within the different fish species and in fish samples of the same species caught in different locations. The fattiness of the fish or the influence of the season had no significant effect on the vitamin D contents in the samples of fish and fish products. On the basis of the study findings, the daily intake of vitamin D from fish and fish products in Finland is estimated to be 4.4 μg/day per capita.