Importance of vitamin A!

                                          Vitamin A                                                                                                   

 Vitamin is very important for human body .It plays an essential role in growth,tissues,eye sight,maintaining healthy skin.
Concentrations of preformed vitamin A are highest in liver and fish oils
 Other sources of preformed vitamin A are milk and eggs, which also include some provitamin A

 Most dietary provitamin A comes from leafy green vegetables, orange and yellow vegetables, tomato products, fruits, and some vegetable oils .

Vitamin A FAT soluble vitamin

Vitamin A, a fat-soluble vitamin found as either preformed vitamin A or provitamin A carotenoids in the diet, plays an important role in the growth and development of several systems in the body. According to the Office of Dietary Supplements, preformed vitamin A commonly comes from animal sources, especially liver.

. However, consuming large quantities of  pro-vitamin A is converted to retinol only as needed, there's danger  ,it  can cause temporary and harmless discoloration of the skin.

Vitamin A is a powerfull anti-oxident

Vitamin A is also a powerful antioxidant and acts as a hormone in the body, affecting the expression of genes and thereby influencing phenotype.
 Retinol is the predominant, active form of vitamin A found in the blood, while retinyl palmitate is the storage form of the vitamin.
 Beta-carotene is a precursor of vitamin A and is found in plants. This "pro-vitamin," in itself an antioxidant, is converted into vitamin A as needed by the body, thereby posing no risk of toxicity.

Vitamin A essential for growth

 Vitamin A is an essential vitamin needed for growth and development, cell recognition, vision, immune function and reproduction.
 This MNT Knowledge Center feature is part of a collection of articles on the health benefits of popular vitamins and minerals. It provides an in-depth look at recommended intake of vitamin A, its possible health benefits, foods high in vitamin A and any potential health risks of consuming vitamin A.

 Recommended intake

The recommended intake of vitamin A varies according to age and sex. Because vitamin A is available in several forms, the vitamin A content in foods is often measured as retinol activity equivalents (RAEs).

One RAE is equal to 1 microgram of retinol, 12 micrograms of beta-carotene or 3.33 IU of vitamin A.

 The recommended intake of RAEs for people of different ages according to the National Institutes for Health (NIH) are as follows :

 1.   0-6 months*: 400 mcg/day
 2.   7-12 months*: 500 mcg/day
 3.   1-3 years: 300 mcg/day
  4.  4-8 years: 400 mcg/day
  5.  9-13 years: 600 mcg/day
  6.  14+ years (male): 900 mcg/day
  7.  14+ years (female): 700 mcg/day
  8.  14-18 years (pregnancy): 750 mcg/day
  9.  14-18 years (lactation): 1,200 mcg/day
  10.  19-50 years (pregnancy): 770 mcg/day
   11. 19-50 years (lactation): 1,300 mcg/day.

Food s sources  of vitamin A

Ready-made retinol, the active form of vitamin A, can only be obtained from animal sources. The richest sources of retinol are:

 1.  Liver
 2.   Fatty fish (like herring and salmon)

3.  Fish oils 

 4.   Butter
  5.  Milk
  6.  Cheese
   7. Eggs

Vitamin A" is the blanket term for retinoids

"Vitamin A" is the blanket term for retinoids, biologically active compounds that occur naturally in both plant and animal tissues.

The vitamin A that comes from animal sources is fat-soluble, and in the form of retinoic acid, retinal and retinol. Because these retinoids are very bioavailable and stored in our tissues, too much animal-derived vitamin A can build up in the body and become toxic.

The vitamin A in fruits and vegetables is in the form of  "provitamin A" 

The vitamin A in fruits and vegetables is in the form of  "provitamin A" -vitamin A precursors also known as  carotenoids, which must be converted by the human body into usable retinoids.
There are several distinct classes of carotenoids, and evidence suggests that carotenoids work together to provide their health benefits. Taken together in supplement form, these are commonly called "mixed carotenoids."
 The body can make all the vitamin A it needs from these plant-derived carotenoids. They are water-soluble and do not accumulate in the body, so toxicity is rare.

Are there risks associated with too much vitamin A?

 Excessive, chronic intake of some forms of vitamin A can be toxic.
 Avoid taking supplemental vitamin A as retinol or retinoic acid, and instead use plant-derived vitamin A precursors such as beta-carotene (in addition to other mixed carotenoids). Also avoid concentrated animal sources such as cod liver oil (although some forms of cod liver oil are vitamin A reduced and are safe - check the label).
 Warning symptoms of overdose include hair loss, confusion, liver damage and bone loss.

Effects of vitamin A:

   1.    Vitamin in A is critical for good vision
  2.     Plays an important role in healthy bone growth
  3.     Vitamin A is essential for reproduction
 4.      Plays a role in cell division and cell growth
 5.      Supports the immune syste
 6.     Supports skin health