Vitamin A deficiency Supervision Prof. 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  -carotene to retinol, thus called provitamin A.

FUNCTIONS Vision:Vision: integrity of eye & formation of rodopsin necessary for dark adaptation. Regulation of gene expressionRegulation of gene expression: vital to cell differentiation & physiologic processes Growth & developmentGrowth & development ImmunityImmunity: 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.Iron & vitamin A. Vitamin A deficiency may exacerbate IDF Vitamin 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  g of retinol = 6  g of  -carotene.  3  g of retinol = 10 international units of vitamin A.  100 mg carrots contain 10 mg of  - carotene.

Life stage  g/day Infants Children Adolescent 900M- 700F Adult Pregnant women Lactating women Recommended Allowance

Animal Foods Plant Foods Cod liver oil Sweet potato Liver & kidney Carrots EggCantaloupe ButterSpinach 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: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