How much vitamin A is in a serving of carrots?
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Carrots don't have vitamin A, they have a chemical that turns into vitamin A inside your body. That chemical is inside the tough cells, so you have to crush the cell walls somehow to expose the pro-vitamin to the digestive process. That means either grinding the carrot very finely or cooking it to softness. So the amount you get from a serving of carrots is a crap shoot.
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Recommended supplement limits
The U.S. Institute of Medicine has established Daily Tolerable Upper Levels (UL) of intake for vitamin A from supplements that apply to healthy populations, in order to help prevent the risk of vitamin A toxicity. These levels for preformed vitamin A in micrograms (µg) and International Units (IU) are
0–3 years: 600 µg or 2000 IU
4–8 years: 900 µg or 3000 IU
9–13 years: 1700 µg or 5665 IU
14–18 years: 2800 µg or 9335 IU
19+ years: 3000 µg or 10,000 IU
The dose over and above the RDA is among the narrowest of the vitamins and minerals. Possible pregnancy, liver disease, high alcohol consumption, and smoking are indications for close monitoring and limitation of vitamin A administration. However, vitamin A has also been repeatedly tested and used therapeutically over several decades in larger amounts. For example, a total dosage of 100,000 - 400,000 IU has been given for treatment of severe pediatric measles, in areas where vitamin A deficiency may be present, in order to reduce childhood mortality.[5][6]
[edit] Toxicity from eating liver
The liver of certain animals — including the polar bear, seal, walrus,[7] and husky — is unsafe to eat because it is extraordinarily high in vitamin A. This danger has long been known to the Inuit and has been recognized by Europeans since at least 1597 when Gerrit de Veer wrote in his diary that, while taking refuge in the winter in Nova Zemlya, he and his men became severely ill after eating polar bear liver.[8] In 1913, Antarctic explorers Douglas Mawson and Xavier Mertz were both poisoned (and Mertz died) from eating the liver of their sled dogs during the Far Eastern Party.[9]
Vitamin A itself was not discovered until 1917.
Pathological changes consistent with hypervitaminosis A have been seen in bones of Homo erectus, and have also been attributed to consumption of carnivore liver.[10]
The livers of many other animals have lower levels of vitamin A and are commonly eaten.
Hypervitaminosis A occurs when the maximum limit for liver stores of retinoids is exceeded. The excess vitamin A enters the circulation causing systemic toxicity. Betacarotene, a precursor form of vitamin A typical of vegetable sources such as carrots, is selectively converted into retinoids, so it does not cause toxicity; however, overconsumption can cause carotenosis, a benign condition in which the skin turns orange.
https://en.wikipedia.org/wiki/Vitamin_A_…
--------------------------------------…
Recommended supplement limits
The U.S. Institute of Medicine has established Daily Tolerable Upper Levels (UL) of intake for vitamin A from supplements that apply to healthy populations, in order to help prevent the risk of vitamin A toxicity. These levels for preformed vitamin A in micrograms (µg) and International Units (IU) are
0–3 years: 600 µg or 2000 IU
4–8 years: 900 µg or 3000 IU
9–13 years: 1700 µg or 5665 IU
14–18 years: 2800 µg or 9335 IU
19+ years: 3000 µg or 10,000 IU
The dose over and above the RDA is among the narrowest of the vitamins and minerals. Possible pregnancy, liver disease, high alcohol consumption, and smoking are indications for close monitoring and limitation of vitamin A administration. However, vitamin A has also been repeatedly tested and used therapeutically over several decades in larger amounts. For example, a total dosage of 100,000 - 400,000 IU has been given for treatment of severe pediatric measles, in areas where vitamin A deficiency may be present, in order to reduce childhood mortality.[5][6]
[edit] Toxicity from eating liver
The liver of certain animals — including the polar bear, seal, walrus,[7] and husky — is unsafe to eat because it is extraordinarily high in vitamin A. This danger has long been known to the Inuit and has been recognized by Europeans since at least 1597 when Gerrit de Veer wrote in his diary that, while taking refuge in the winter in Nova Zemlya, he and his men became severely ill after eating polar bear liver.[8] In 1913, Antarctic explorers Douglas Mawson and Xavier Mertz were both poisoned (and Mertz died) from eating the liver of their sled dogs during the Far Eastern Party.[9]
Vitamin A itself was not discovered until 1917.
Pathological changes consistent with hypervitaminosis A have been seen in bones of Homo erectus, and have also been attributed to consumption of carnivore liver.[10]
The livers of many other animals have lower levels of vitamin A and are commonly eaten.
Hypervitaminosis A occurs when the maximum limit for liver stores of retinoids is exceeded. The excess vitamin A enters the circulation causing systemic toxicity. Betacarotene, a precursor form of vitamin A typical of vegetable sources such as carrots, is selectively converted into retinoids, so it does not cause toxicity; however, overconsumption can cause carotenosis, a benign condition in which the skin turns orange.
https://en.wikipedia.org/wiki/Vitamin_A_…