Vitamins

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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
• Fat soluble (A D E K )
• Water soluble
• Thiamin B 1
• Riboflavin B2
• Niacin B3
• Pyridoxin B6
• Biotin
• Folate
• Cobalamin B12
• Ascorbic Acid C

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Vitamin A

• SOURCE
• 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
• Is the initial part of the photoreceptor complex
  in rods of retina
• It induces the differentiation of epithelial
  cells and in deficiency state mucous secreting
  cells are replaced by keratin producing cells
• It is necessary for fetal development,
  haematopoisis and immune functiondeficient
  children suffer from severe respiratory infectons
  and gasteroenteritis

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• DEFICIENCY
• Blindness is the most important, ocular features
  pass through stages
• 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
• Loss of normal mucous cells in the cornea which
  takes a dull hazy lackluster appearance due to
  keratinization (xerophthalmia)
• Keratomalacia, leading to ulceration , scarring
  and irreversible blindness

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• 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

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Vitamins

• Cont.

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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

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• 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

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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

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• 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

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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

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• DEFICIENCY
• In neonatesthe 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

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Water soluble vitamins
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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

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• 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

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• 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

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• 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

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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 its 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

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• 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

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• Treatment
• Oral or parenteral nicotinamide, the response is
  usually rapid
• within 24 hrs erythema diminishes , diarrhea
  ceases and a striking improvement in patients
  behavior occur

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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.

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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

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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

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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

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• 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