Chapter 12 Fat Soluble Vitamins Flashcards
Where can vitamin ADEK dissolve in?
Organic solvents such as ether and benzene. They are referred to fat-soluble vitamins.
Where can vitamin B and C dissolve in?
Water. They are called water-soluble vitamins.
Why vitamin important in diet?
Because it cannot be synthesized in body.
How to qualify a substance as vitamin?
Health decline when the substance is not consumed.
Absorption of vitamins
Vitamin ADEK are absorbed together with fat. It depends on efficient bile and pancreas use. 40% to 90% of fat soluble vitamin can be absorbed, and 90% to 100% of water-soluble vitamin can be absorbed. It happens in small intestinal.
What can lead to malabsorption of vitamin?
Alcohol abuse and certain intestinal disease.
Where will vitamin be transported after absorption?
lymphatic system and delivered by the bloodstream to target cells throughout the body in a manner similar to that for dietary fats.
Where are the vitamins stored in the body
Except vitamin K, fat-soluble vitamin are not readily to excrete from body. They are stored in the liver and adipose tissue. And water-soluble vitamins are excreted rapidly.
Two vitamins which has greater storage than other water-soluble.
Vitamin B12 and B6.
The vitamin toxicity most likely occur?
Vitamin A and D.
When will vitamin toxicity occur?
Vitamin toxicity is unlikely to occur unless the amount of intake is 5 or 10 times to the DRI.
Retinoid
A collective term for the biologically active forms of vitamin A. It is called performed because it does not need to be converted in the body to become biological active.
Three forms of retinoid
Retinol(alcohol), retinal(aldehyde), and retinoic acid.
Carotenoid
Are yellow-orange pigment material in fruits and vegetables. They can be converted into vitamin A. Only alpha-carotenoid, beta and beta-crypotoxanthin can be converted to vitamin. Thus other carotenoid do not have vitamin A activity in body.
Where can retinoid be found?
Liver. fish, fish oil, fortified milk, and eggs.
Where can carotenoid found?
Dark green and yellow- orange vegetables and fruits, such as carrots, spinach and other greens.
Beta-carotene
It has the greatest amount of provitamin A activity. It provide the yellow-orange color to vegetables and fruits. The color is masked by the green color provided by the chlorophyll. Therefore, consuming a varied amount of dark green food and yellow-orange food can provide VA.
Unit for vitamin A
UI in the past. Milligram or microgram now.
How to express vitamin A activity in diet?
RAE (Retinal Activity Equivalent).
1 RAE equals to
1 microgram retinol, 12 microgram beta-carocarotene, and 24 μg of the other 2 provitamin A carotenoids.
RE
Retinol Equivalent. Older measurement for vitamin A activity. 1RE = 1 RAE. Actually food contains less vitamin A than RE and UI suggest.
RDA for vitamin A
900 microgram RAE per day for men and 700 for women.
What compounds are performed vitamin A found in food?
retinol and retinyl ester compounds. Retinol compounds attached with fatty acid. Retinyl ester doesn’t have vitamin A activity until retinol separate from fatty acid in intestinal acid.
How much retinol can be absorbed ?
90% can be absorbed into cells of small intestinal via specific carrier protein.
What happened after absorption
A retinol attached with a fatty acid and form a new retinyl ester compound. These retinyl esters are packaged into chylomicrons before entering the lymphatic circulation.
Digestion of carotenoid
Carotenoid is attached with proteins that must be split off before absorption. Once freed, it will be absorbed primarily by passive diffusion.
Absorption range of carotenoid
5% to 60% of intake.
After vitamin A released from liver
It is bound to a retinol-binding protein.
Synthesis of RBP needs
Retinol-binding protein. The synthesis of RBP needs adequate amount of retinol, protein, and zinc.
What happened when retinol in the bloodstream?
They are bound with another protein called transthyretin.
What happened after carotenoid released from liver?
They are carried by lipoproteins and are taken up into cells by specifi c apoprotein receptors.
The distribution of RBPs
Differs among tissues, possibly reflecting their different functional needs for vitamin A.
Excretion of vitamin A
Retinoid is excreted via urine. Carotenoid is excreted via bile that is eliminated with feces.
Key function of retinoid.
Development and growth, cell differentiation, vision, and immune function.
Role of VA during the embryonic
VA is involved in the development of eyes, limbs, the cardiovascular system, and the nervous system.
What happens if lack of VA during the pregnancy ?
Birth defects and fetal mortality.
The function of retinol acid
Production, structure, and normal function of epithelial cells in the lungs, trachea, skin, and GI tract, as well as in many other systems. It is important for the formation and maintenance of mucous-forming cells in these organs.
The function of cell differentiation
In the cell nucleus, retinoid bind to 2 main families of retinoid receptors. These receptors bind with DNA site that regulate the formation of RNA and the subsequent formation of protein through gene expression. Gene expression directs cell-differentiation.