Why do Arctic predators accumulate vitamin A?

Question

Top predators in the Arctic are known to accumulate vitamin A, often to levels that are toxic for human consumption. A 2012 study by Senoo, Imai, *et al.* found that the livers of several predator species in the Arctic showed much higher levels of vitamin A than other Arctic species or closely related continental species, with no symptoms of hypervitaminosis A. Why is it that these species accumulate vitamin A? Does this have something to do with the food sources available in the Arctic as opposed to the mainland? Or are there physiological reasons why Arctic predators would tend to accumulate vitamin A rather than breaking it down or otherwise eliminating it? **References:** * Senoo, Haruki; Imai, Katsuyuki; Mezaki, Yoshihiro; Miura, Mitsutaka; Morii, Mayako; Fujiwara, Mutsunori; Blomhoff, Rune (2012). "Accumulation of vitamin A in the hepatic stellate cell of arctic top predators". *Anatomical Record* **295** (10): 1660–8. doi:[10.1002/ar.22555](https://dx.doi.org/10.1002%2Far.22555). PMID [22907891](https://www.ncbi.nlm.nih.gov/pubmed/22907891).

Answer 1

Vitamin A is found in high amounts in animal fats such as butter, fat on ribeyes, etc. These Arctic animals have much higher levels of fat than normal animals to insulate against the cold weather. The high fat content of the diet of Arctic animals and hunters is also important to offset the oxidative damage the harsh sun UV rays do to cells at a DNA level. Additionally, liver is a high source of vitamin A. Hunters and predators are known to eat liver meat due to its high source of iron and other nutrients difficult to come by in the Arctic.