Vitamins. Vitamins are organic substances which are required in very small amounts but are not synthesized in the body, occur naturally in food and are.

Vitamins

• Vitamins are organic substances which are required in very small amounts but are not synthesized in the body, occur naturally in food and are essential for health

Two types1. Fat soluble (A D E K )

2. Water soluble • Thiamin B 1• Riboflavin B2• Niacin B3• Pyridoxin B6• Biotin • Folate• Cobalamin B12• Ascorbic Acid C

Vitamin ASOURCE : only available in animal source, liver is the richest source Also produced in the intestine by splitting of carotenes (present in

green vegetable and carrot)

FUNCTION:1. Is the initial part of the photoreceptor complex in rods of retina

2. It induces the differentiation of epithelial cells and in deficiency state mucous secreting cells are replaced by keratin producing cells

3. It is necessary for fetal development, haematopoisis and immune function;deficient children suffer from severe respiratory infectons and gasteroenteritis

DEFICIENCY :

• Blindness is the most important, ocular features pass through stages:

A. Night blindness: is the earliest sign and results from an impairment of dark adaptation. The diagnosis is supported by low plasma retinol concenteration and confirmed by a marked improvement in dark adaptation following therapeutic doses of retinol

B. Loss of normal mucous cells in the cornea which takes a dull hazy lackluster appearance due to keratinization (xerophthalmia)

C. Keratomalacia, leading to ulceration , scarring and irreversible blindness

Treatment:• A therapeutic dose (large single dose 60 mg ) of oral retinol is given

immediately after diagnosis, repeated on the next day and once then after in the follow up visit

• Intramuscular injections are given if there was vomiting or severe diarrhea

Prevention:• Pregnant women advised to eat green leafy vegetables and yellow

fruits to built up stores of retinol in fatal liver

• Babies also should have such vegetables and locally available carotene rich fruits

• Single prophylactic dose of retinol given to preschool children with measles and in countries where xerophthalmia is endemic

Vitamins

Cont.

Vitamin D SOURCE: • The major source is natural, is formed in the skin by the

action of ultraviolet light on 7 hydroxy cholecalciferol • The minor source is dietary, includes egg yolk, oily fish,

butter and milk .

FUNCTON:• Cholecalciferol(D3) is converted in the liver to 25 OH(D3)

then to 1,25 OH (D3) in the kidneys which is the active form • It increases the uptake of calcium in the gut and in bone

formation

DEFICIENCY :• Poor bone mineralization causing rickets in children and

osteomalacia in adults.

• This occurs more in elderly and dark skinned individuals who produce lesser vit D in their skin, in malabsorption syndrome and chronic kidney diseases when the conversion to active form is impaired

Vitamin E SOURCE:• Vegetable oil , wholegrain , cereals and nuts

FUNCTION:• It is an important antioxidant that prevents the oxidation of

polyunsaturated fatty acids in the cell membrane by free radicals

• Maintenance of cell membrane structure, participating in

DNA synthesis and cell signaling • Protection against coronary heart disease probably through

protecting LDL from oxidation and hence reducing atherosclerosis

DEFICIENCY :

• It is rare and only seen in premature infants and in malabsorption

• The first feature is mild hemolytic anemia

• In chronic fat malabsorption ;ataxia and visual scotoma which responds to vit E

Vitamin K SOURCE :

• Adequate amounts in leafy vegetable and liver• Synthesized in colon by bacteria

FUNCTION:

• Required for the synthesis of clotting factors in which it acts as a cofactor for the production of gamma carboxyglutamic acid which is a residue of clotting factors II , VII , IX , X

DEFICIENCY:• In neonates;the bowel has not yet acquired bacteria to

synthesis vit K and breast milk contains little amounts, these render neonates develop a hemorrhagic disease

• In obstructive jaundice ;vit K is not absorbed • Warfarin act by antagonizing vit K action

PREVENTION :• Giving vit K routinely to neonates to prevent hemorrhagic

disease• Parenteral administration of vit K to patients with

obstructive jaundice especially preoperatively

Water soluble vitamins

Vitamin B1 “thiamin”

• It is involved in the carbohydrate metabolism ,acts as a coenzyme in the hexose monophosphate shunt and krebs cycle

In deficiency states:• Cells cannot metabolize glucose aerobically which affects

brain first because it depends largely on glucose as energy requirements

• The accumulation of pyruvate and lactic acid produces vasodilaton and increases cardiac output

Source :• Is richly distributed in both vegetable and animal

sources, cereals being the main source

• The body has a very limited stores of B1 thus ;deficiency state appears after a month from thiamin free diet

Deficiency : • in chronic alcoholics and people consuming diet

consisting mainly of polished rice

• Infantile beri beri seen exclusively among infants of deficient mothers which is invariably fatal

• Dry or neurological beri beri manifested as peripheral neuropathy with wrist drop and /or foot drop and may manifest with korsakoff psychosis or wernicke encephalopathy

• Wet or cardiac beri beri with generalised odema due to heart faliure and pulmonary congestion

Management :

• Wernicke encephalopathy should be treated without delay with iv thiamin followed by daily im injecton for a week ,the response is rapid “2-3 days “ this confirms the diagnosis also

• Korsakoff's psychosis is irreversible and does not respond to thiamin treatment

• Wet beri beri is a medical emegency needing iv thiamin

Vitamin B2 “riboflavin”• It is a part of the oxidative phosphorylation in the

mitochondria ,acting as a coenzyme in the oxidation reduction reactions

Source :• richest source being milk and it’s non fat products Deficiency :• Mainly affect the tongue and lips manifest as glossitis ,

angular stomatitis and cheilosis• The genitals may be affected as well as facial skin which are

rich in sebaceous glands causing nasolabial dyssebacea Treatment : • With oral ribofalvin causes rapid recovery•

Niacin • Nicotinic acid and nicotinamide have equal biologic

activity , considered together as niacin• Nicotinanmide is an essential part of NAD and NADPH

which play an important role in the metabolism

Source :• it is synthesized in the body in limited amount from

tryptophan; Egg and cheese are rich in niacin

Deficiency :• Pellagra :Results from deficiency of niacin which can

develop within 8wks in individuals eating diet deficient in niacin, encountered occasionally among alcoholics, small intestinal diseases, in Hartnup disease and carcinoid syndrome

Clinical features : 3Ds

• Dermatitis :characteristically erythema resembles severe burns appearing symmetrically over parts of body exposed to sunlight especially on the neck called casal ‘s necklace.

• Diarrhea :often associated with anorexia, nausea , glossitis and dysphagia

• Dementia :especially in chronic cases ,in severe cases delirium occurs acutely

Treatment :• Oral or parenteral nicotinamide, the response is

usually rapid; • within 24 hrs erythema diminishes , diarrhea ceases

and a striking improvement in patient’s behavior occur

Pyridoxine “vitamin B6”• the active form in human being acts as a coenzyme

in a large number of amino acid metabolic reactions

Source :• richest source being meat , fish potatoes and

banana

Deficiency :• Although rare as a dietary deficiency, but more

common with certain drugs like isoniazide and D-penicillamine which antagonize the action of pyridoxal.

Biotin • Acts a coenzyme in the carbohydrate , amino acid

and fatty acid metabolism Deficiency :• Although rare to be due to dietary deficiency but

occasionally seen among patients consuming large amounts of raw eggs which binds to biotin and deactivates it within the intestine

Clinical features :• Scaly dermatitis, alopecia , and parasthesia

Vit B12• The dietary requirements are very small, it is only available in animal

products , hence vegan are at risk of developing vit B 12 deficiency • Normal liver contains enough store to cover the requirements for

years

Deficiency: • The haematological feature is megaloblastic anemia

• The neurological disease sometimes predominates: B12 (not folate) is needed for the integrity of mylin

• In severe deficiency there is demylination manifested as peripheral neuropathy, spinal cord degeneration, dementia and optic atrophy

• Treatment with vit B12 is usually beneficial but often slow

Folic acid • Involved directly in the synthesis of DNA and RNA , higher

than normal is required during embryonic lifeSource :• Liver is the richest source in addition to leafy vegetables

and fruitsDeficiency :• Three major defects from imperfect closure of neural tube

(spina bifida , anencephaly and encephalocele)arise during embryonic life

Prevention :• Oral folate through out first trimester of pregnancy

prevents neural tube defects in the newborn •

Vitamin C “Ascorbic acid” • Is a strong reducing agent involved in the intracellular

electron transfer. It is necessary for the formation of collagen

• High doses suggested to improve immune function including resistance to common cold and cholesterol turnover.

Source :• Fresh fruits but destroyed easily by heat hence by

traditional cooking

Oral vit C saturates the deficiency Associated anemia should be corrected by iron and folic acid

Deficiency :• Scurvy :defective formation of collagen, capillary

hemorrhage, impaired healing of wounds and subnormal platelet function

It is seen in people who avoid eating fruits for more than 2-3 months and in infants fed on boiled milk only

Clinical features :• Swollen , spongy gums that bleed easily • Perifollicular , petechial or spontaneous bleeding• Hemorrhages into joint and GIT • Anemia and poor wound healing