Why do polar bears need so much vitamin A?

So why is it so lethal? Arctic predators such as polar bears have a greater capacity to store vitamin A in their liver than most other animals. It is thought to be because of the effect of naturally occurring vitamin A in marine algae being passed up the food chain to the polar bear.

Why do arctic animals have so much vitamin A?

The phytoplankton at the bottom of the food chain have high levels of vitamin A and precursors like beta-carotene. At each step up the chain, vitamin A bioaccumulates. Top predators in the Arctic deal with this by storing the vitamin A in the liver (bears, cetaceans) or blubber (pinnipeds).

How much vitamin A is in polar bear liver?

One pound of polar bear liver — a fist-sized chunk and barely a meal — can contain 9 million units of vitamin A.

Why can’t you eat a polar bear’s liver?

A polar bear’s liver contains an extremely high concentration of vitamin A. … Ingesting the liver can cause vitamin A poisoning known as acute hypervitaminosis A. This results in vomiting, hair loss, bone damage and even death.

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Why do seals have so much vitamin A?

The seals store high levels of vitamin A in order to swiftly grow and nourish their young in a harsh, chilly environment. Remember, vitamin A plays a key role in growth and natal development. The seals rely on this vitamin to quickly advance them through their vulnerable pup stages.

Why is vitamin A toxic?

Megadoses of vitamin A can cause liver toxicity. Although carotene is converted to vitamin A in the body, excessive ingestion of carotene causes carotenemia, not vitamin A toxicity. Carotenemia is usually asymptomatic but may lead to carotenosis, in which the skin becomes yellow.

Do polar bears eat humans?

Bears. Polar bears, particularly young and undernourished ones will hunt people for food. … Truly man-eating bear attacks are uncommon, but are known to occur when the animals are diseased or natural prey is scarce, often leading them to attack and eat anything they are able to kill.

How much vitamin A is toxic?

Too much vitamin A can be harmful. Even a single large dose — over 200,000 mcg — can cause: Nausea. Vomiting.

Can vitamin A toxicity be reversed?

A person can often reverse hypervitaminosis A by stopping taking excess amounts of vitamin A. This may mean that they can no longer take multivitamins or vitamin A supplements. If there are no complications, a person will usually recover quickly.

What are the symptoms of vitamin A toxicity?

Most people with vitamin A toxicity have a headache and rash. Consuming too much vitamin A over a long period of time can cause coarse hair, partial loss of hair (including the eyebrows), cracked lips, and dry, rough skin. Chronic consumption of large doses of vitamin A can cause liver damage.

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Can eating liver cause vitamin A toxicity?

It is possible, and even dangerous, to consume too much vitamin A. Eating large amounts of liver can lead to symptoms of vitamin A toxicity. Your own liver cannot process the excess vitamin A quickly enough, so eating a significant amount of liver regularly might lead to hypervitaminosis A.

Do polar bears eat penguins?

Polar bears do not eat penguins, since penguins live in the southern hemisphere and polar bears live in the northern hemisphere.

What animal has the strongest liver?

The basking shark. Its liver, which may account for 25% of its body weight, runs the entire length of the abdominal cavity and is thought to play a role in buoyancy regulation and long-term energy storage.

How much vitamin A should I take?

The recommended daily allowance (RDA) for vitamin A is 900 mcg and 700 mcg per day for men and women, respectively — which can be easily reached by following a whole-foods diet ( 27 ). However, it’s important not to exceed the tolerable upper limit (UL) of 10,000 IU (3,000 mcg) for adults to prevent toxicity ( 27 ).

How is vitamin A toxicity treated?

The most effective way to treat this condition is to stop taking high-dose vitamin A supplements. Most people make a full recovery within a few weeks. Any complications that occurred from the excess vitamin A, such as kidney or liver damage, will be treated independently.

Why is seal meat illegal?

The U.S. and Europe have each banned the import of seal because of the cruel way some people hunt the animals. … But the Canadian government allows seal hunting, saying that it provides a sustainable, healthy meat to many Arctic populations that have no other source of nourishment.

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