March 6 2013 Nutrition Lecture
Aneta is a health consicious 45 yr old woman,…?
Cereal has fortified with K. The says 2% of daily requirement of cereal. IF she
consumes 2 servings per day with 2% milk at breakfast, which of the following is
true (**TEST TYPE QUESTIONS)
Ans: A and E.
(Calculation gives 188mg Kday. Milk too contains potassium)
Vitamin A and Beta-Carotene
Vitamin is one of the fat soluable vitamins , and in body exists as RETINOIDS:
retinol ; retinal and retinoic acid.
All are forms of Vit A but have specific roles
Retionic Acid (has its own function)
You don’t get VIT A form food or plant, you get COMPOUND (carotenoids )that
can be converted to Vit A
The most well-known is beta carotene (because it gets converted to VIT A much
easily, readily, compared to the other compounds called retinyl esters)
Animal foods retinyl esters and can be converted to retinol
If you want to determine how much VIT A is in your system? You can measure by
measuring it how much VIT A is in your blood and you measure retinol (that is the
form that moves from one part to another)
Fat soluable vit don’t move freely in the blood they need to be carried around. VIt
A also needs to have Retinol Binding protein from one tissue to another.
Beta cartotene absorption is poor because.
Beta carotene absorption is not as good compared to retinyl esters.
Even when u have absorbed beta carotene u need 12 units of betacarotene for 1
unit of VIT A that is produced. Diff forms of vit A performs diff functions
Retinal to retinol and retonic acid conversion is easy
You cannot back from retinoic acid to retinal or retinol
helps maintain the cornea
conversion of light energy into nerve impulses
Rhodopsin is made up of opsin and cis-Retinal(form of VIT A). When you
have light shining on Rhodopsin it basically leads conversion of cis-retinal to
When you have that transformation the trans Retinal cannot bind to opsin. The
serration of Rhodopsin that leads to destruction of membrane which nerve cells
send messages to brain and you are able to see.
Retinal maintains integrity of cornea
VIT A is important in Protein synthesis and Cell Differentiation
Epithelial cell: Cells that lie on the external surfaces of the body. The surfaces of
the GI tract. All the way from esophagus to colon.
Urinary , reproductive, the trachea, all have ephitleial cells
Vit A is very important as it stimulates globulet cells to make mucus which helps
keeps the surface moist.
Vit A maintains healthy cells in the mucous membranes.
Roles in the body
Reproduction invovled in sperm production
-invovled in embryo development
-VIT A involved in protein synthesis,
VIT A, is involved in Osteoclasts (bone breaking)
Osteoblast (making bones) Remodeling of bones osteoclasts is first process it breaks bones and new
bones are made using osteoblasts
Lysosomes = bag of enzymes they degrade proteins/ need vit A to do what they
have to do.
Beta-carotene can do something as VIT A. AS you can convert VIT A to Beta-
VIT A you can get from beta carotene
Beta-carotene can act as an antioxidant
VIT A and Beta-Carotene
VIT A stored in liver.
For how long somebody can go without VIT A depends on diff factors?
Depends on their Protein Status Vit A Deficiency is a big nutrition problem. Lack of VIT A it can have implication
for their immune status.
-Measles the severity depends on the VIT A
People living in third world coutries have access to sufficient amount of vit. A
maize contains a lot of beta carotene
The region in which the main source of food is corn and they consume some sort
of corns that contain beta carotene the consumption of a lot of beta carotene can
help produce or maintain vit. A, levels one of the signs observed with vit A
deficiency is night blindness ,
If u sit in the dark for a couple of min and then u turn on the lights u will
experience a moment of darkness but u recover because u have enough
retinal ( the process has been described)
People living in regions of the world where they have problems regarding their vit
A requirements, one of the things they will experience is night blindness that is
they are not able to see or work at night
The lack of vit A in retina leads to this the part of eye involved is retina
The role of vit A in eye (two regions discussed)
If somebody has a lot of retonic acid in their body can they experience
Even though an individual has enough of vit A in retinoic acid form. Retinoic acid
is kind of a dead end when it comes to the end of conversion so this individual
might have a lot of retinoic acid but if he lacks retinal in retina he is going to end
up like night blindness.
Somebody having vit a deficiency in any other any other part of the eye can
experience more devastating effects specifically blindness simply because if we
don’t have enough retinal in the cornea u r able to maintain integrity of that site
that is going to lead to cirrhosis which is why the