fat soluble vitamins -A

1. Fat -soluble vitamins
RUSUDAN TCHIGVARIA

2. Vitamin A , D, E, K

3. Fat Soluble Vitamin
Form Micelles in jejunum
• Cluster of lipids
• Hydrophobic groups inside
• Hydrophilic groups outside
Absorbed by entrocytes
Packed into chylomicrons
Secreted into Lymph
Carried to liver as chylomicron remnants

4. Fat Malabsorption
 Leads of deficiencies of fat-soluble vitamins
 abnormal bile or pancreatic secretions
 Disease or resection of intestine
Key Causes
• Cystic Fibrosis
• Celiac Sprue
• Crohn’s Disease
• Primary biliary cirrhosis
• Primary sclerosing cholangitis

5. Vitamin A
Retinol= Vitamin A
Retinoids
 Family of structures
 Derived from vitamin A
 Important for VISION , GROWTH, EPITHELIAL TISSUES
 Key retinoids: retinal, retinoic acid

6. Beta Carotene
Pro- vitamin A ( a carotenoid )
Major source of vitamin A in diet
Cleaved into retinal
Antioxidant properties
 Similar to vit C, vit E
Protects against free radical damage
 May reduce risk of cancers and other diseases

7. Retinal
Found in VISUAL pigments
Rods, cones in retina
Rhodopsin= light-sensitive proteins receptor
I. Generates nerve impulses based on light
II. Contains Retinal

8. Retinoic Acid
Binds with receptors in nucleus- acts like a hormone
Regulates/ controls protein synthesis
Important example : KERATIN
 limit/control keratin production
 retinoic acid used in treatment of psoriasis
 deficiency : Dry skin
Important example : Mucous
limit/ control mucous production epithelial cells

9. VITAMIN A
Dietary sources
 found in liver
 Dark green and yellow vegetables
Many people under-consume Vitamin A
Stored in liver( years to develop deficiency)

10. Vitamin A deficiency
Visual symptoms
 Night blindness ( often first sign )
 Xerophthalmia (Keratinization of cornea -> blindness)
 Keratinization
 Skin : thickened , dry skin
Growth failure in children

11. Bitot spot (areas of abnormal squamous cell
proliferation and keratinization of the
conjunctiva) caused by vitamin A deficiency.
This picture was taken in Lebanon and used as
a clinical standard for examiners in
international nutrition surveys.

13. Therapy
Measles
Mechanism not clear
Used in resource-limited countries
Skin disorders – psoriasis , Acne
Atherosclerosis
Very low birthweight infants

14. Vitamin A
AML – M3 subtype ( acute promyelocytic leukemia
• all-trans-retinoic acid ( ATRA/tretinoin )
• Synthetic derivative of retinoic acid
• induces malignant cells to complete differentiation
• Become non-dividing mature granulocytes/ macrophages

15. Isotretinoin
Accutane
13-cis-retinoic acid
Effective for acne
Highly teratogenic
OCP and/or pregnancy test prior to Rx

16. Vitamin A
Excess
Hypervitaminosis A
 Usually from chronic, excessive supplements
 Dry, itchy skin
 Enlarged liver
 Increased cerebrospinal fluid pressure (pseudotumor cerebri).
Adverse effects on bone
Cancer
Teratogenic effects