Possible Factors Responsible for the High Variation in the Cholecalciferol Contents of Fish

Previously a high variation was found in the cholecalciferol (vitamin D 3 ) contents of fish samples representing the same species but caught in different habitats in Finland. The present study was designed to provide reasons for this variation. The influences of various factors, e.g. weight, age, and sex of the fish as well as the cholecalciferol content of zooplankton, on the cholecalciferol contents of fish flesh were studied. Perch, vendace, and pike samples were caught in three different types of lakes, and perch, Baltic herring, and pike samples were caught in the Baltic Sea. Zooplankton samples were caught in all four habitats. The cholecalciferol determinations were performed with HPLC after purification with preparative HPLC. No consistent relationship between the weight, sex, or age of the fish and cholecalciferol content was found. According to this study, it is possible that diet is a likely factor which causes the variation in the cholecalciferol contents of the fish.