All About Vitamins

Vitamin A
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Why vitamin A is good for you

Vitamin A is essential for healthy eyes as it helps the eyes to function properly in all conditions, even the dark. Vitamin A is essential in preventing night blindness.

Vitamin helps to prevent a leading case of blindness in the elderly called age-related macular degeneration (ARMD).

Vitamin A helps the immune system fight infection and illness by helping the epithelial tissues (the cells that make up the skin, line the mouth, nose, eyes, throat, lungs, digestive and urinary tracts and which keep out infective agents) grow and repair themselves. Without enough vitamin A, these cells become stiff, dry and much more likely to let their guard down and when that happens, germs can easily pass through them and into the body.

All humans (especially children and teenagers) need vitamin A for a wide range of body functions, including to help the body cells repair, grow properly and to keep bones and teeth strong.

 

Important vitamin A facts

Vitamin A can be found preformed in animal foods such as egg yolks, meat and fish.

There are three forms of preformed vitamin A:

  • retinol
  • retinaldehyde and
  • retinoic acid

Retinol is destroyed by light, high temperatures as well as when using copper or iron cooking utensils


The highest source of vitamin A is the polar bear liver, which has 13,000IU-18,000IU per gram of liver!! More than enough to give vitamin A poisoning, even if only a tiny bit was eaten

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Groups at risk of vitamin A deficiency

Talk to a medical professional about vitamin A supplements BEFORE taking them.

 

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Symptoms of vitamin A deficiency

 

 

A deficiency of vitamin A may lead to eye problems with dryness of the conjunctiva and cornea, dry skin and hair, night blindness as well as poor growth. Dry itchy eyes that tire easily are normally a warning of too little vitamin A.

If the deficiency becomes severe, the cornea can ulcerate and permanent blindness can follow. The hair and scalp can also become dry with a deficiency, especially if protein is also lacking. Insomnia, fatigue and reproductive difficulties may also be indicative of vitamin A is in short supply.


Major symptoms of deficiency are
:

 

vitamin A and health

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vitamin A in food

FOOD AMOUNT
Vitamin A (IU)
Beef liver
85g
9,000
Chicken liver
100g
4,913
Skim milk
1 cup
149
Ice-cream, vanilla
1 cup
133
Egg
1 large
97
Cheddar cheese
28g
86
Swiss cheese
85g
72
Chicken drumstick, with skin
1 piece
45
Yoghurt, low fat
230g
36
Butter
1 tsp
35
Swordfish
85g
35
Salmon
85g
11

 

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vitamin A recommended daily intake (RDI)

RDA lifestage age Amount
  INFANTS 0-6mths
7-12mths
400mcg (1320IU)
500mcg (1650IU)
  CHILDREN 1-3yrs
4-8yrs
300mcg (1000IU)
400mcg (1320IU)
  CHILDREN 9-13yrs
male: 14-18yrs
female: 14-18yrs
600mcg (2000IU)
900mcg (3000IU)
700mcg (2310IU)
  ADULTS male: 19-50yrs
female: 19-50yrs
900mcg (3000IU)
700mcg (2310IU)
  SENIORS male: 51+yrs
female: 51+yrs
900mcg (3000IU)
700mcg (2310IU)
  PREGNANT <18yrs
19-50yrs
750mcg (2500IU)
770mcg (2565IU)
  LACTATING <18yrs
19-50yrs
1200mcg (4000IU)
1300mcg (4300IU)
 
TOLERABLE UPPER LIMIT lifestage age Amount
  INFANTS 0-12mths 600mcg (2000IU)
  CHILDREN 1-3yrs
4-8yrs
600mcg (2000IU)
900mcg (3000IU)
  CHILDREN 9-13yrs
14-18yrs
1700mcg (5610IU)
2800mcg (9240IU)
  ADULTS 19-50yrs 3000mcg (10000IU)
  SENIORS 51+yrs
3000mcg (10000IU)
  PREGNANT <18yrs
19-50yrs
2800mcg (9240IU)
2000mcg (10000IU)
  LACTATING <18yrs
19-50yrs
2800mcg (9240IU)
3000mcg (10000IU)
 
TOXIC LEVELS >25,000IU per day
>8,000IU per day for females of child bearing age


The tolerable upper limits should only be taken for short periods and only under medical supervision.

Retinol Equivalents (IU and mcg)

The above recommended dietary allowances of Vitamin A are given in Retinol Equivalents (RE) of vitamin A (in mcg).

The following shows the International Unit (IU) equivalents of Vitamin A:

One Retinol Equivalent (RE) of Vitamin A (in mcg) =
   6 International Units (IU) from beta-carotene
   10 IU from other carotenoid-rich plant foods
   4.10 IU from milk and yogurt
   3.33 IU from animal sources and fortified foods

 

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vitamin A works best with

 

 

 

Overdosage, toxicity and cautions for vitamin A

NOTE: High intake of vitamin A during pregnancy is NOT recommended as it may cause birth defects. Women of child-bearing age should not take more than 8,000IU of vitamin A per day for this very reason.

Vitamin A is toxic in large doses and should not be taken. To avoid vitamin A toxicity, take Betacarotene instead.

People who are alcoholics are advised not to take high levels of Vitamin A because their liver may be too sensitive from the alcohol abuse and therefore more susceptible to liver toxicity of vitamin A.

Symptoms of overdosage in children are:


Symptoms of overdosage in adults are:



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references

 

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Last reviewed: 1 January 2009 || Last updated: 1 January 2009

 

NOTE: Mega doses of vitamins, minerals, amino acids, or other supplements cannot cure illnesses and in fact can be very dangerous and produce toxic side effects and interfere with medicine you are taking. Always ensure you consult your doctor before taking any type of nutrient supplement.
Disclaimer: This guide is not intended to be used for diagnostic or prescriptive purposes. For any treatment or diagnosis of illness, please see your doctor.

 

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