Friday, December 28, 2012

Vitamin A

It has been a while since I've had a chance to post anything.  Things have been pretty busy for me between volunteering, and tutoring.  With the arrival of the holidays, things have been increasingly insane, but I have finally had a chance to post something.

This is something I have been working on for a while, once I am done, I may actually approach a friend of mine to see if we can come up with a 'perfect diet' based on required intake of nutrients.  I want to give an overview of vitamins, highlighting the importance, sources and dangers of over consumption for each kind.  Understandably, this is going to be an extremely long post, so I have since broken it up into different parts.  the first one will be Vitamin A, but I will post Vitamin B as soon as possible.  Please feel free to email me if you want any clarification on what is being said.  A lot of what I have in here is based off of my University Biochemistry and Human Anatomy books.

Vitamin A – What is It??
Vitamin A exists in two forms depending on the type of food we are eating.  When eating animals, vitamin A is in the form of retinyl palmitate, which is converted into Retinol in our lower intestine.  When consuming plant matter, Vitamin A is present in the form of carotenes, which are converted into retinol in our lower intestine.  Vitamin A is essential to the proper function of our eyes.  In our eyes, there are two main types of cells, called rods and cones (based on their shape), The rods and cones are the very first step in translating the light we see into an image in our brains.  Within the rods and cones, there are molecules that are called photopigments that absorb light.  The photo-sensative part of the pigment is called retinal and is created from Vitamin A. Vitamin A also assists with gene transcription.  It has been said that Vitamin A helps boost your immune system, however, this may not be entirely accurate.  Vitamin A deficiency leads to a weakened immune system, so taking Vitamin A may only restored your immune system to normal levels.

Where Do You Get it From?
The Top 10 food for obtaining Vitamin A are (in descending order of concentration):

1.       Liver – 75,333IU in 100g
2.       Spices
a.       Paprika – 52,735IU/100g  
b.      Cayenne – 41,610IU/100g
3.       Sweet Potatoes – 19,218IU/100g
4.       Carrots – 16,706IU/100g
5.       Dark Leafy Greens – 15376IU/100g
6.       Butternut Squash – 11,155IU/100g
7.       Dried Herbs
a.       Parsley – 10,184IU/100g
b.      Basil – 9,385IU/100g
c.       Marjoram – 8,037IU/100g
d.      Dill – 7,688IU/100g
e.      Oregano – 6889IU/100g
8.       Lettuce (Red or Green Leaf Lettuce) – 7492IU/100g
9.       Dried Apricots – 3,604IU/100g
10.   Cantaloupe – 3,382IU/100g

How much do we need?

*1µg is equal to 3.3 IU

What Happens if You Don’t get Enough?
As you can tell from what Vitamin A does, a Vitamin A deficiency leads to a loss of eye sight. The early signs of a Vitamin A deficiency are reduced vision in low light (aka: night blindness).  A continued deficiency  gradually leads to the destruction of the cornea and then total blindness.  Other effects of a deficiency are an impaired immune system.  An adequate supply is essential for pregnant women since the effects cannot be reversed by obtaining enough Vitamin A after birth.

What Happens If You Have Too Much?
First, it is important to note that Vitamin A is Fat Soluble, because of this fact, it takes a lot longer to remove excess Vitamin A from your system than Vitamin B and Vitamin C, which are water soluble.  Toxicity can occur when absorbing more than 15,000IU a day, this happens particularly with excessive alcohol consumption.  A mild amount of Vitamin A overdose can lead to nausea, irritability, anorexia,  vomiting,  blurry vision,  headaches, hair loss, muscle and abdominal pain and weakness, drowsiness, and altered mental status.  If the toxicity level becomes chronic, all of the mild symptoms can be present in addition to: hair loss, dry skin, drying of the mucous membranes, fever, insomnia, fatigue, weight loss, bone fractures, anemia, and diarrhea.

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