Download Vitamins - Shanyar

Vitamins
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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 types
1. Fat soluble (A D E K )
2. Water soluble
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Thiamin B 1
Riboflavin B2
Niacin B3
Pyridoxin B6
Biotin
Folate
Cobalamin B12
Ascorbic Acid C
SOURCE :
Vitamin A
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 :
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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
SOURCE:
Vitamin E
• 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
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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 Dpenicillamine 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 life
Source :
• Liver is the richest source in addition to leafy vegetables
and fruits
Deficiency :
• 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
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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 23 months and in infants fed on boiled milk only
Clinical features :
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Swollen , spongy gums that bleed easily
Perifollicular , petechial or spontaneous bleeding
Hemorrhages into joint and GIT
Anemia and poor wound healing