Vitamin A
Alrighty folks, hopefully posting about vitamin A will lead to an A on the exam this week! That would be A-mazing, A wonderful result.. I would be A happy student. Okay, I’m done now.
This is obviously my personal blog based on my own thoughts and opinions. However, I wanted to make the following very clear:
“ Disclaimer: This information below is from my notes during my Vitamins, Minerals, and Nutraceuticals graduate level course. This is based on my understanding of these notes and should be not used as medical advice in any way. If you feel you are in need of help with Vitamin deficiency or toxicity, please consult a physician or other medical treatment* “
There are over 600 carotenoids found in nature! Only a handful are actually found in fruits and veggies usually consumed, absorbed and deposited into our bodies tissues and blood. Dietary carotenoids are converted into “Vitamin A” within our bodies.
The term “Vitamin A “ is used to refer to several forms of the vitamin: retinol, retinal, retinoic acid. Retinol is only found in animal sources.
The term “Provitamin A” actually refers to Beta-Carotene and other carotenoids that exhibit similar activity of the carotenes such as alpha-carotene, lycopene, lutein, etc. These compounds considered as Provitamin A are only found in plants.
Confused yet?
• One molecule of Beta-Carotene is actually two molecules of “vitamin A” stuck together.
• Beta-carotene can be cleaved and form 2 molecules of retinal, theoretically, which can then be converted to either retinoic acid or retinol.
• RAE (retinol activity equivalent)were developed as a system of adding up all the carotenoids in the foods that would equal the activity of Vitamin A
• 1 miligram of retinal ( equal to 1 RAE ) can be formed by 6 mg of Beta-Carotene Okay, so why do we need this Vitamin A or RAE or Carotenoids?
• Retinoic Acid is crucial for gene expression, thyroid function, cell function and growth
o Leukemia cells treated with retinoic acid have been shown to stop cell proliferation ( hence stop the cancer from continuing)
o Retinoic Acid also controls formation of fingers in fetus development o Some studies have shown retinoids inhibit carcinogenesis!
• Retinol is crucial for reproductive processes
• Another big one that Retinol takes care of is… you guessed it, Vision! (retinol binds to opsin in our eyes and produces rhodopsin, which then breads down after light hits it. A form of retinal that is produced from that leads to the impulse sent to the optic nerve-hence we see!)
Deficiency:
One of the first signs you are deficient is a decrease in night-vision.
The most common cause of blindness in children in the entire world is from Vitamin A deficiency, causing over 250,000 cases of blindness each year!
This deficiency is commonly seen with children also suffering from Protein Energy Malnutrition and the measles, increasing the rate of mortality by 10-20%, and more common in “developing countries”
Xerophthalmia is the general term covering all eye manifestations due to Vitamin A deficiency. Why is it such a big issue in developing countries?
• Diets in the developing countries are typically based off staples: Maize, Rice, Wheat and Roots—– all of these are very low in beta-carotene and retinoids.
• These diets also tend to be extremely low in fat, unfortunately, you need fat in order to absorb Vitamin A.
• Even consumption of cow or human milk doesn’t help because those are both low in Vit. A
• Green, leafy and colorful vegetables are also not consumed nor produced as much in these areas- which are the greatest sources carotenoids!
• Early signs of deficiency include decreased appetite, decreased growth, impaired immune system and increased risk infection. Decreased eye function is the next stage, and then eventually death
TOXICITY!
Acute Toxicity:
Signs of this include headaches, vomiting, and stupor. The good news is that withdrawal of the vitamin A forms usually reverses this condition very rapidly.
After several months or years of toxic “Vitamin A” levels:
Signs will include decreased appetite, flakey skin, hair coarsening, new bone growths, double vision and menstrual problems. The good news again is that withdrawal quickly reverses these issues.
Hypercarotenosis:
This condition is an excess intake of Beta-Carotene and causes your skin to turn yellowish orange. This condition is actually rather harmless. Often, diets high in carrots and sweet potatoes typically can produce this condition but it is only from the excess beta-carotene- it is not a sign of “toxicity”.
I mentioned earlier in this post- you do not consume “Vitamin A” rather you consume forms such as Beta-Carotene or retinoids that are then converted in our bodies to what we refer to as “Vitamin A”.
The other forms of Vitamin A are typically what cause the toxicity levels, at which point you see the signs noted above.
As I also mentioned, carotenoids play a role in thyroid function as well. Hypothyroidism can also cause a similar hypercarotenois because the carotene is not being metabolized properly, thus lying around. However, if it is a thyroid issue, typically the whites of your eyes will also turn yellow- if its only from carrot-loving- it usually is just the skin. Cutting back on the foods high in carotenoids will alleviate the symptoms!
I leave you with this again:
* Disclaimer: This information is from my notes taken in my Vitamins, Minerals, and Nutraceuticals graduate level course. This based on my understanding of these notes and should be not used as medical advice in any way. If you feel you are in need of help with Vitamin deficiency or toxicity, please consult a physician or other medical treatment*
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