Vitamin A Flashcards
Is Vitamin A a water soluble or fat soluble vitamin?
It is a fat soluble vitamin
How many forms of vitamin A are there?
There are two forms
What are the two forms of vitamin A called?
Retinol
Beta-carotene
What is retinol?
It is pure vitamin A
Is retinol easy or difficult to absorb?
It is easy to absorb
Where is retinol stored in the body?
The liver
What is beta-carotene?
It is pro-vitamin A
Is beta-carotene easy or difficult to absorb?
It is difficult to absorb
Why is beta-carotene difficult to absorb?
It has to be converted into retinol in the lining of the intestine
List the properties of retinol
5
A yellow, fat-soluble alcohol
Insoluble in water
Soluble in organic solvents e.g. acetone
Heat stable, but affected by prolonged high temperatures
Destroyed by oxygen
List the properties of beta-carotene
6
A yellow or orange fat-soluble oil
Insoluble in water
Soluble in fat solvents, e.g. alcohol
Heat stable, but affected by prolonged high temperatures
Unaffected by oxygen
Powerful antioxidant
What effect do antioxidants have on the body?
They have the ability to counteract the damaging effects of free radicals
List the sources of retinol
8
Fish liver oils Milk Eggs Butter Offal Cheese Margarine Oily fish
List the sources of beta-carotene
6
Carrots Tomatoes Red peppers Leafy green vegetables Apricots Sweet potatoes
Retinol usually comes from what type of food?
Animal sources
Beta-carotene usually comes from what type of food?
Carotenoids which are yellow, green and orange fruit and vegetables
List the functions of vitamin A
5
Manufactures rhodopsin in the retina
Helps maintain healthy skin and mucous membranes
Healthy skin and hair
Aids growth and development
Beta-carotene acts as a powerful antioxidant
Vitamin A aids in the manufacture of rhodopsin in the retina, describe this function
Vitamin A is required to manufacture the pigment rhodopsin found in the retina which helps the eye adapt to dim light
Vitamin A helps maintain healthy skin and mucous membranes, describe this function.
Vitamin A helps maintain healthy skin and the mucous membranes of the body such as the eyes, nose and throat which prevents infection
List the effects of a deficiency of vitamin A
5
Night blindness
Follicular hyperkeratosis
Xeropthalmia
Stunted or delayed growth in children
Damage to cells/cancer
A deficiency of vitamin A results in night blindness, describe this deficiency
One with night blindness will struggle to see in dim light due to a lack of rhodopsin
A deficiency of vitamin A results in follicular hyperkeratosis, describe this deficiency
This is a condition that results in rough, dry skin and inflamed hair follicles
A deficiency of vitamin A results in xeropthalmia, describe this deficiency
(2)
This occurs on the surface of the eye due to a lack of mucous
This causes eyes to dry out and become infected with bacteria and can eventually lead to blindness
A deficiency of vitamin A results in damage to cells and an increased risk of cancer, describe this deficiency
Damage to cells by free radicals increases the risk of some cancers, coronary heart diseases and strokes
What is the RI for children?
400-500 micrograms
What is the RI for adolescents and adults?
600-700 micrograms
What is the RI for pregnant women?
700 micrograms
What is the RI for lactating women?
950 micrograms
