community main seminar - copy

8/6/2019 Community Main Seminar - Copy

1/53

SEMINAR BY:

DR. KRISHI MOHAN

INTERN (2006 BATCH)


2/53

y Introduction

y Definition

y Classification

y Vitamin Ay Vitamin D

y Vitamin E

y

Vitamin Ky Bibliography


3/53

y These are essential organic substancesy Yield no energy, but facilitate energy-yielding chemical reactionsy If absent from a diet, it will produce deficiency signs and

symptomsy Fat-soluble vitamins A, D, E, Ky Water-soluble vitamins B1 (Thiamin), B2 (Riboflavin), B3

(Niacin), B5 (Panthothenic acid), B6 (Pyridoxine), B9 (Biotin),B12 (Cyanocobalamin ), Folic acid and Vitamin Cy Preservation of vitamins in foods

y exposure to light, heat, air, water, and alkaline


4/53

y Vitamins may be regarded as organic compoundsrequired in the diet in small amounts to performspecific biological functions for normal maintenance

of optimal growth and health of the organism


5/53

VITAMINS

FAT SOLUBLE WATER SOLUBLE

NON B- COMPLEX

ENERGY RELEASING

B COMPLEX

HAEMATOPOIETIC

VITAMIN A

VITAMIN C

FOLIC ACID

VITAMIN D

THIAMINE B1

CYANOCOBALAMIN B12

VITAMIN E

PYRIDOXINE B6

RIBOFLAVIN B2VITAMIN K

BIOTIN B7

NIACIN B3

PANTOTHENIC ACID


6/53

y found in fats and oilsy require bile for absorption

y enter the lymph, then the blood

y dissolve in organic solvents

y not readily excreted; can cause toxicity

y transported like fat in chylomicrons, VLDL, LDL

y held and stored in fatty tissuesy

daily requirements need not be met


7/53

y 3 forms in the body

y retinol

y retinal

y retinoic acid

y collectively known as retinoidsy found in food derived from animals

Retinol, the alcohol form Retinal, the aldehyde form Retinoic acid, the acid form

Beta-carotene, a precursor

Cleavage at this point can

yield two molecules of vitamin A*


8/53


9/53

The variety of functions performed by Vitamin Aare,

1. Vision

y Vision: The biochemical function for the same was

elucidated by George Wald (Nobel Prize 1968).y The event occur in a cyclic process known as

Rhodopsin Cycle or Walds Visual Cycle.


10/53

DietDiet

carotene carotene RetinylestersRetinylesters

FFAFFA

RetinolRetinol

ChylomicronsChylomicrons

RetinolRetinol

RBPRBP

Retinol RBPRetinol RBP RBPRBP

Intestinal cell

carotene

Retinal

RetinolFFA

Retinylesters

Retina

All-trans retinol

All-trans retinal

Visual cycle

Target cell

Retinol

Retinoic acid

Specific proteins

Cell differentiation

Liver:All-trans

retinol

Retinylpalmitate(stored)

mRNA


11/53

y Vision is based on absorption of light by photoreceptor cells in the eye.

y Vertebrates have two kinds of photoreceptor cell, called rods & cones

because of their distinctive shape.y Cones(300million)function in bright light and are responsible for color

vision.

y Rods(100 million) function in dim light but do not perceive color.

y Rods contain photoreceptor molecules called rhodopsin

y Rhodopsin consists of a protein opsin linked to 11-cis retinal (aprosthetic gp) which gives the rhodopsin its ability to absorb light.

y Absorbtionof light result in the isomerization of 11-cis retinal into all-trans retinal.


12/53

y

Promote vision (retinal)y Maintenance of the corneay Converting light energy into nerve impulses

y Participate in protein synthesis and cell differentiationy Differentiation of epithelial and goblet cells

(retinoic acid)y Support reproduction and growthy Support immunity (retinoic acid and carotenoids)y Involved in bone growth and remodelingy Synthesis of glycoproteinsy

Antioxidant activity (-carotene)


13/53


14/53

2. Retinol and retinoic acid function almost likesteroid hormones. They regulate proteinsynthesis and thus are involved in cell growth anddifferentiation.

3. It is essential to maintain healthy epithelial

tissue, because retinol and retinoic acid arerequired to prevent keratin synthesis.Further, retinyl phosphate is essential for the

formation of mucopolysaccharides compounds ofmucus secreted by epithelial cells to maintain

moist surface.


15/53


16/53

7. Cholestrol synthesis requires Vitamin A.Mevalonate, an intermediate in the cholestrol

biosynthesis, is diverted for the synthesis ofcoenzyme Q in Vitamin A deficiency.

8. Carotenoids ( most important carotene)function as antioxidants and reduce the risk of

cancers initiated by free radicals and strongoxidants. carotene is found to be beneficialto prevent heart attacks. This is also attributedto the antioxidant property.

9. Decrease in gluconeogenesis in Vitamin Adeficiency is observed which is secondary tothe reduced synthesis of glucocorticoids.


17/53

Vitamin A - Deficiency

In dim light, you can make out the details in

this room. You are using your rods for vision

A flash of bright light momentarily blinds

you as the pigment in the rods is bleached.

With inadequate vitamin A, you do not recoverbut remain blinded for many seconds.

You quickly recover and can seethe details again in a few seconds.

Night blindness: Leading cause of blindness in third world countries


18/53

y Cell keratinizationy Dry skiny Xerophthalmia (dryness of cornea & conjunctiva)

curable early stage

after 8 days vitamin A

incurable late stages


19/53


20/53

y Hyperkeratosis and hyperplasia of gingival tissues

y Hypoplastic and chalky white incisors

y Atrophy of odontoblasts

y Atrophy of salivary glands leading to xerostomia causingincrease in caries

y Crowding of teeth

y Stunting and thickening of the roots

y Dental caries

y Disturbances in differentiation and function of ameloblastsy Thick, regular labial dentin with interglobular spaces

y Thin, atubular lingual dentin


21/53


22/53

y Upper safe levels are 4- to 10-fold higher thanrequirements in nonruminants and 30-50-foldhigher than requirements in ruminants

y Not readily excretedy Hypervitaminosis A in humans

y Polar explorers eating polar bear or seal liver

y Self-medication and overprescription


23/53


24/53


25/53

y Not always essentialy Body can make it if

exposed to enoughsunlight

y Made from cholesterolin the skin


26/53

y Not found naturally inmany foods

y Synthesized in body

y Plants (ergosterol)y Sun-cured forages

y Fluid milk products arefortified with vitamin D

y Oily fish

y Egg yolk

y Butter

y Liver

y Difficult for vegetarians


27/53

yVitamin D = calciferol

yVitamin D2 = ergocalciferoly Completely synthetic form produced by the irradiation

of the plant steroid ergosteroly Plant source cannot be used by birds

yVitamin D3 = cholecalciferoly Produced photochemically by the action of sunlight or

ultraviolet light from the precursor sterol 7-

dehydrocholesteroly Animal source required by birds


28/53


29/53

y Functionsy Bone development

y Calcium absorption (small intestine)

y Calcium resorption (bone and kidney)

y Maintain blood calcium levels

y Phosphorus absorption (small intestine)

y Hormoney Regulation of gene expression

y

Cell growth


30/53

y Osteoclastsy Break down bone

y Calcium resorption

y Derived from stem cells

y Differentiate after stimulation by vitamin Dy Osteoblasts

y Bone-forming cells

y Secrete collagen, which calcifies

y Bone contains 6066% Ca by weighty Hydroxyapatite, Ca10(PO4)6(OH)2


31/53

y Younger age groupy Rickets

y Failure of bones to grow properlyy Results in bowed legs or knock-

knees, outward bowed chest andknobs on ribs

y Older age groupy Osteomalacia: Adult form of rickets

y Softening of bones, bending of spine,and bowing of legs

y Osteoporosis (porous bones):y Vitamin D plays a major role along

with calciumy Loss of vitamin D activity with

advancing agey Associated with fractures very

serious for geriatrics


32/53

y Hypoplasia and hypocalcification of enamel and dentin

y Calciotraumatic line seen during dentin formation is theearliest sign of deficiency.

y

Hypomineralized dentiny Increased width to predentin

y Odontoblastic disorganization

y Enlarged pulp and pulp horns

yTooth defects more severe in males

y Permanent teeth affected predominantly

y Short, wedge shaped roots with delayed apical closure


33/53

y Interglobular calcification in dentin, especially atapices

y Enamel hypoplasia

y Enlarged pulp chambers

y Irregular dentinal tubules

y

Small crowns and short blunted rootsy Pitted enamel surfaces

y Retarded jaw, tooth and condyle development

y Generalized jaw bone resorption

y Loss of the periodontal ligament


34/53

y Calcification of soft tissuey Lungs, heart, blood vesselsy Hardening of arteries (calcification)

y Hypercalcemiay Normal is ~ 10 mg/dly Excess blood calcium leads to stone formation in kidneys

y Lack of appetite

y Excessive thirst and urination


35/53

Type II (age-related) osteoporosisy Loss of bone mass

y Limited ability to absorb vitamin D or produce it

y 10-20 ug vitamin D/ day plus calcium decrease bonefracture

y Risk for hypercalcemia

Psoriasisy Skin disorder

y Topical treatment


36/53

y Tocopherols

yAmount absorbed is dependent on fat intakey Incorporated into micellesy Requires bile and fat digesting enzymes

y Transported via chylomicrons to the liver

y Transported via VLDL, LDL, HDL from the liver

y Found concentrated in areas where fat is found

y Excreted via bile and urine (much in feces due tolimited absorption)


37/53

y Plant oils

y Wheat germ

y Asparagus

y

Peanutsy Margarine

y Nuts and seeds

y Actual amount is

dependent on harvesting,processing, storage andcooking


38/53

y Antioxidanty Free radical scavenger

y Protects cell membranesy Protects LDL from oxidationy Protection of double bonds in

polyunsaturated fatty acidsy Prevention of rancidityy Works in conjunction with

selenium

y Protects lungs from

pollutantsy Protects DNAy Protects heart


39/53

y Protects the double bonds in saturated fat

y Role in iron metabolism

y Inhibits LDL oxidation

y Inhibits protein kinase C activity

y Enhance release ofprostacyclin

y Maintenance of nervous tissue and immune function

y No specific role in metabolic reaction


40/53

y 15 mg/day for women and men

y (=22 IU of natural source or 33 IU of synthetic form)

y Average intake meets RDA


41/53


42/53


43/53

y Supplements up to 800 IU is probably harmless

y Upper Level is 1,000 mg/day of any form ofsupplementary alpha-tocopherol

y Upper Level is 1500 IU (natural sources) or 1100 IU(synthetic forms)

y Inhibit vitamin K metabolism and anticoagulants


44/53

y 40%-80% of dietary vitamin K is absorbed

y Absorption requires bile and pancreatic enzymes

y Role in the coagulation processy Calcium-binding potential


45/53

y Liver

y Green leafy vegetables

y Broccoli

y Peas

y Green beansy Resistant to cooking losses

y Limited vitamin K storedin the body


46/53

y K1, phylloquinoney Chloroplasts in plants

y K2, menaquinone

y Bacterial synthesis

y K3, menadioney Synthetic, water soluble formy Complexed to improve stability


47/53

y Clotting factors aresynthesized in the liver asinactive precursors - vitamin Kconverts them to their activeformsy Conversion of prothrombin to

thrombin, an active enzyme

y Formation of fibrinogen tofibrin, leading to clot

formationy Stimulates bone formation and

decreases bone resorption


48/53

y 90 ug/day for women

y 120 ug/day for men

y RDA met by most

y

Excess vitamins A and E interferes with vitamin Ky Newborns are injected with vitamin K(breast milk is a

poor source)

y Toxicity unlikely; readily excreted


49/53

y Primary deficiency rare; secondary deficiencyoccurs when fat absorption is impaired (e.g., cysticfibrosis, Crohns disease) or following long-term orhigh-dose administration of antibiotics (they killthe bacteria in large intestine)y Newborn babies with sterile GI tract; single vitamin K

dose given to prevent hemorrhage

y Prolonged clotting time

y Generalized hemorrhages


50/53

y Excessive gingival bleeding

y Dental caries


51/53

y Not common except with over-supplementationy Phylloquinone and menaquinone are relatively nontoxic

y Jaundice; brain damage

y Menadione toxic to skin and respiratory tract in highdoses


52/53


53/53

community main seminar - copy

Documents