“Many health conscious individuals avoid cod liver oil and other foods rich in vitamin A because of concerns about vitamin A toxicity. Yet, according to the Merck Manual, vitamin A poisoning is rare. In adults, vitamin A toxicity has been reported in Arctic explorers who developed drowsiness, irritability, headaches and vomiting, with subsequent peeling of the skin, within a few hours of ingesting several million units of vitamin A from polar bear or seal liver. These symptoms cleared up with discontinuation of the vitamin A rich food. Other than this unusual example, however, only vitamin A from “megavitamin tablets containing vitamin A. . . when taken for a long time” has induced acute toxicity, that is, 100,000 IU synthetic vitamin A per day taken for many months. Unless you are an Arctic explorer, it is very difficult to develop vitamin A toxicity from food.”
Yes, I didn’t suggest avoiding Vitamin A (retinol) rich foods. Other than of course polar bear or sled dog liver.
Only saying that if supplementing, I recommend beta-carotene instead and that is presently being very widely accepted, though no doubt not universally (almost nothing is.)
As for cod liver oil, if consumed in amounts similar to what one might consume if eating a reasonable amount of cod, then I think it’s fair to count that as a food source. But if the amount of isolated oil is well beyond what a person might reasonably consume from cod, then I would call that supplementation. Traditional amounts of cod oil usage are, I expect, fine. Megadosing I think counts as a poor idea: no added benefit reasonably to be expected, and possible detriment. You just don’t need extreme Vitamin A and excess may well be a poorer thing to do than getting a reasonably correct amount.
“Many health conscious individuals avoid cod liver oil and other foods rich in vitamin A because of concerns about vitamin A toxicity. Yet, according to the Merck Manual, vitamin A poisoning is rare. In adults, vitamin A toxicity has been reported in Arctic explorers who developed drowsiness, irritability, headaches and vomiting, with subsequent peeling of the skin, within a few hours of ingesting several million units of vitamin A from polar bear or seal liver. These symptoms cleared up with discontinuation of the vitamin A rich food. Other than this unusual example, however, only vitamin A from “megavitamin tablets containing vitamin A. . . when taken for a long time” has induced acute toxicity, that is, 100,000 IU synthetic vitamin A per day taken for many months. Unless you are an Arctic explorer, it is very difficult to develop vitamin A toxicity from food.”
Another reason to not eat polar bear liver.[/quote]
Who would imagine lol.
I don’t know. It’s an interesting question. Is it somehow an adaptation to living in extreme cold? If it is, I have no idea why, nor do I have any idea of it is so. My only reason for wondering it is the odd coincidence.
We don’t hear about Chinese people overdosing on Vitamin A from eating the livers of regular dogs, as most likely they do, as they do eat dogs. So it would seem the same species may have differing Vitamin A content in the liver according either to the breed or the climate.
My theory is that Vitamin A, being stored as a reserve in the livers of many animals, is stored in higher amounts for animals who don’t eat frequently. A hibernating bear would need a ton of Vitamin A stored. I’m sure the dogs living in extreme cold probably do not eat often either. The ones whose livers could safely store th e highest amount of vitamin A, were the ones who survived the longest.
Vitamin A utilization is hampered by cold, so arctic animals might adapt to storing more. Also, vitamin A is necessary to prevent night blindness, and these animals spend half the year in the dark. Perhaps they’ve adapted to storing much, much more.