vitamin a deficiency supervision prof. dr. mervat salah
TRANSCRIPT
Vitamin A deficiency
SupervisionProf. Dr . Mervat Salah
Intended Learning Outcomes
- By the end of this lecture, students will
have a general overview on vitamin A in it’s
deficiency health outcomes.
BACKGROUND
Vitamins are organic substances that are essential for several enzymatic functions in human metabolism
Thiamine was discovered in 1912 & was thought to be a vital amine compound & thus the term vitamin was invented
VITAMINS
Vitamins are classified according to solubility into fat soluble & water soluble.
13 vitamins are known, 4 fat soluble (KEDA) & 9 water soluble (C, Folate & the B group).
VITAMIN A Vitamin A is a generic term for many related compounds.
Retinol (alcohol), Retinal (aldehyde) are often called preformed vitamin A. Retinal can be converted by the body to retinoic acid which is known to affect gene transcription. Body can convert b-carotene to retinol, thus called provitamin A.
FUNCTIONS
•Vision: integrity of eye & formation of rodopsin necessary for dark adaptation.•Regulation of gene expression: vital to cell differentiation & physiologic processes
•Growth & development
•Immunity: important for activation of T lymphocyte, maturation of WBC & integrity of physiological barrier.
Nutrient Interactions•Zinc deficiency interfere with vitamin A metabolism in several ways: It decreases the synthesis of retinol binding protein, which transports retinol to tissues.
It decreases the activity of the enzyme retinyl palmitate, which is necessary for release of retinol from the liver.
Zn is needed for the enzyme that convert retinol into retinal.
Nutrient Interactions/2•Iron & vitamin A.
Vitamin A deficiency may exacerbate IDFVitamin A supplementation improves iron
status among children & pregnant women.Combining vitamin A with iron controls
IDA more quickly & effectively than using iron alone.
VITAMIN A UNITS
1 mg of retinol = 6 mg of b-carotene.
3 mg of retinol = 10 international units of vitamin A.
100 mg carrots contain 10 mg of b-carotene.
Life stage mg/dayInfants 400-500
Children 300-600
Adolescent 900M- 700F
Adult 900M- 700F
Pregnant women 750-800
Lactating women 122-1300
Recommended Allowance
Animal Foods Plant Foods
Cod liver oil Sweet potato
Liver & kidney Carrots
Egg Cantaloupe
Butter Spinach
Milk & cheese Apricot
Fish & meet Papaya
RICH DIETARY SOURCES
Vitamin A deficiency
•Deficiency of vitamin A leads to:
Night blindness & xerophthalmia
Growth retardation
Acquired immune deficiency
Keritinization of epithelia in RT, GIT & UT with increased risk of RTI, malabsorption & UTI.
THERAPEUTIC USES
Vitamin A deficiency
Boosting immunity of infants
Skin disorders
Acute promyelotic leukemia
Cancer prevention (lung & breast)
TOXICITY
•Vitamin A in excess leads to:• Dermatitis with xanthosis cutis
• Hepatosplenomegaly
• Bone pain & increased risk of fracture
• Pseudotumor Cerebri
Xeropthalmia in rat - dryness of the cornea
Early stages are curable
Cured with 6 days treatment with Vitamin A
Vitamin A deficiency Night Blindness
Follicular hyperkeratosis. Goose flesh. Pustulation occurs and is
confused with acne.
Histological section of skin. Hair follicle with hyperkeratosis. (Excess
keratinized tissue).
Recommended text book
Manual dietetic book