NHM 101 Lecture Notes - Lecture 14: Retinol, Vitamin K, Chylomicron
Ch 11 - Fat-Soluble Vitamins
Vitamins A, D, E, K
- Hydrophobic
- Insoluble in GI tract
- Requires bile to be digested and absorbed
- Requires a transport protein
- Absorption:
- Lymph system first (chylomicrons)
- Then to blood stream
- Excess is stored in adipose tissues and liver
- Body retrieves fat-soluble vitamins from storage when needed
- So they are not readily excreted
- Risk of toxicity is greater
Vitamins and Disease Prevention
Cardiovascular
Disease
Cancer
Osteoporosis
E
A
D A K
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Vitamin A
Different forms:
● Retinol
(alcohol form)
● Retinal
(aldehyde form)
● Retinoic Acid
(acid form)
● Carotenoids- pigments found in plants that have vitamin activity
○ Carotenoids can be converted to Vitamin A
○ E.g. beta carotene can be split to form 2 retinols
Functions:
● Regulate the expression of genes
● Vision
○ Maintains a clear cornea
○ Conversion of light energy into nerve impulses at the retine
● Part of protein synthesis and cell differentiation to maintain the health of epithelial
cells and skin
○ Vitamin A protects skin from sun damage
● Support reproduction and regulate growth
○ Participates in sperm development
○ Supports fetal growth
● Beta carotene acts as an antioxidant
Recommendations:
RDA
Men- 900 mcg/day
Women- 700 mcg/day
UL
3000 mcg/day
Food Sources:
Milk products
Eggs
Liver
Beta carotene
● Dark green leafy vegetables
● Deep orange fruits/veggies
○ Apricots, cantaloupe,
squash, carrots, sweet
potatoes, and pumpkin
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Document Summary
Requires bile to be digested and absorbed. Excess is stored in adipose tissues and liver. Body retrieves fat-soluble vitamins from storage when needed. Carotenoids- pigments found in plants that have vitamin activity. Carotenoids can be converted to vitamin a. E. g. beta carotene can be split to form 2 retinols. Conversion of light energy into nerve impulses at the retine. Part of protein synthesis and cell differentiation to maintain the health of epithelial cells and skin. Vitamin a protects skin from sun damage. Apricots, cantaloupe, squash, carrots, sweet potatoes, and pumpkin. Deficiency symptoms would not appear for 1-2 years in an adult, even after minimal intake in the diet. 250 million children have vitamin a deficiency. Night blindness is one of the first detectable signs. Individuals lose the ability to recover from the temporary blinding of a bright light at night. Vitamin a deficiency is the #1 cause of preventable blindness in the world.