Exam 2 - Fat soluble Vitamins basics and Vitamin A

how are fat soluble vitamins absorbed

passive diffusion via micelles

how are fat soluble vitamins transported

via lipoproteins

enterocytes use which lipoprotein to transport fat soluble vitamins

chylomicrons

what are the fat soluble vitamins

A, D, E, K

which two fat soluble vitamins require digestion

A, E

how much fat is needed to enhance absorption of fat soluble vitamins

5-10g

what are the 2 forms of Vit A

preformed (active)

proformed

preformed vit A is found in what products?

animal

what is the storage form of vit A

retinol Ester

what form of Vit A do we eat

retinol ester

retinol oxidizes to form the aldehyde version called: ___ which oxidizes to form the carboxylic acid form called: ___

retinal, retinoic acid

proformed vitamin a is found in what products

plants: red, orange, yellow colors

carotenoids

carotenoids have an important function, what is this

act as an antioxidant

absorption of proformed carotenoids is limited compared to preformed vit a, what is one way that can enhance absorption of the proformed version

cooking

which form of Vitamin A is super toxic? How does the body combat this?

Retinol (alcohol)

binds to cellular retinol binding protein (CRBP)

where is Retinol reesterified to a retinol ester? What enzyme does this?

enterocyte

lecithin: retinol acyl transferase

where is 70% of vitamin A stored

liver

what are the 3 ways Vitamin A is dealt with by the body

use, store, export

what is required to allow vitamin a to leave the liver

zinc and protein

zinc and protein allow vitamin a to leave the liver because they aid in forming what

retinol binding protein

what is the main function of retinol

reproduction and growth

retinol can oxidize to form retinal. What is the function of this form?

vision (part of rhodopsin)

retinol can also be converted into retinoid acid. What is the function of this acid?

gene expression, cell differentiation, immune system support

certain genes contain retinoic acid receptors (RAR) or retinoic X receptors (RXR). What do these receptors facilitate

expression of specific genes

____-retinol activates the JAK/STAT pathway which leads to genes of the nucleus affecting regulation of ____ and lipid metabolism

CRB, insulin

what is the most utilized form of vitamin a

retinoic acid

decreased vitamin A can lead to decreased rhodopsin being created by the rods of the retina. This can lead to what

night blindness

what is an example of vitamin a playing a role in cell differentiation

keratinizing cells mature into mucus secreting cells

a deficiency in Vitamin A can lead to what skin condition

follicular hyperkeratosis - failure of keratizing cells to mature

carotenoids have no dietary toxicity, but too much supplementation can lead to increase risk for ___

cancer

too much of the preformed version of vitamin a can lead to what

birth defects, blurred vision, bone fractures

what is the primary cause of a vitamin a deficiency? what is the secondary cause?

inadequate intake

fatty malabsorption

someone can be low in what cofactor and look like they are deficient in vitamin a

zinc

what are some vitamin a deficiency symptoms

night blindness

dry eye (xerophthalmia)

bitot's spots (keratin in eye)

Vit A deficiency is the leading cause of _____ blindness in the world? It is the leading cause of ____ blindness in children?

preventable, nutritional

who is at risk of vit a deficiency

premature infants

pregnant women

cystic fibrosis patients

excess dietary vitamin A decreases absorption of what vitamin? what does this lead to?

k, decreased clotting

vitamin A is required for absorption, transportation, and utilization of what

iron