ABSTRACT
Tocopherol concentrations in animal fats are generally much lower than in vegetable oils. Because fish do not synthesize tocopherol, the levels in fish oil are directly related to the fish's diet (Ackman and Cormier 1967). α-Tocopherol is generally the only tocopherol naturally present in marine fish (Ackman and Cormier 1967, Aminullah Bhuiyan et al. 1993, Hemre et al. 1997), and thus also in commercial fish oils. The other tocopherols are likely filtered out by the many invertebrates intermediate between phytoplanktons and fish (Sigurgisladottir et al. 1993). The concentration of α-TOH determined in samples of five commercial fish oils is given in Table 2.3 (Kinsella, 1987). Commercial refining and deodorization, however, are known to substantially reduce the concentration of α-TOH. Because oilseed meals are now commonly added to commercial aquaculture feeds, farmed fish may have somewhat higher levels of tocopherols other than α-TOH.
