One of the early
findings in the history of vitamin D research
was that some species of
fish contain concentrations of vitamin D
in liver or in other soft tissues that are much higher than in the
tissues of any terrestrial vertebrates [1]. The chemical form of
vitamin D in
fish tissues is cholecalciferol. For any
fish species the
concentration may vary over a wide range. For example, the
cholecalciferol content of the oil extracted from cod liver is
reported to vary from 0.7 to 12.5 mg/g [2]. Much of the
cholecalciferol in cod liver is esterified with long chain fatty acids
[3], and hence, may be considered as an inactive or possibly a
storage form. In contrast, vitamin D fatty acid esters are a very
minor component of the vitamin D molecules in mammalian
tissues [4]. Therefore, the accumulation of esterified cholecalcifer-
ol in lipid may explain why some species of
fish, unlike mammals,
have high concentrations of this molecule in liver and other tissues.
One of the early
findings in the history of vitamin D research
was that some species of
fish contain concentrations of vitamin D
in liver or in other soft tissues that are much higher than in the
tissues of any terrestrial vertebrates [1]. The chemical form of
vitamin D in
fish tissues is cholecalciferol. For any
fish species the
concentration may vary over a wide range. For example, the
cholecalciferol content of the oil extracted from cod liver is
reported to vary from 0.7 to 12.5 mg/g [2]. Much of the
cholecalciferol in cod liver is esterified with long chain fatty acids
[3], and hence, may be considered as an inactive or possibly a
storage form. In contrast, vitamin D fatty acid esters are a very
minor component of the vitamin D molecules in mammalian
tissues [4]. Therefore, the accumulation of esterified cholecalcifer-
ol in lipid may explain why some species of
fish, unlike mammals,
have high concentrations of this molecule in liver and other tissues.
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