Vitamins







Vitamins 

N.I.Lunin(1881) discovered  vitamins. Hopkins  and  Funk(1912)profounded a    'Vitamin Theory'. Vitamin was chemically  an amine  and was vital  to life. Hence  Funk ( 1911)  named  it Vitamine ( L.vita_  life+ amine  = vital  amine). The book  entitled   ' The   vitamins ' was  written   by Funk and published  in 1922.  
Vitamin A was the first fat  soluble  vitamin to be discovered. 

First Vitamin  to be isolated  was, B1 ( Funk 1911).

Vitamin  C was  the first vitamin  to be produced  during  fermentation  process  using, Acetobacter, a wild  bacterium  by Albert Szent  Gyorgyi. Vitamin C is  the most sensitive  of  all vitamins to heat. 

Vitamine B12 is absent in plants. It  is considered  that Spirulina (an   alga) contains B12. 

Vitamins  are accessory  food  substances. Vitamins  do not  provide  energy.  They are not used as  structural  units. 

Antineuritic  vitamins  are B1.B6 and B12. Antioxidant  vitamins  are A, E, and  C. Nature's  most potent antioxidant is Vitamin E.






VITAMINS : 


 Vitamins  are complex chemical substances. They are required  by the body in very small amounts. They do not yield energy  like fats or carbohydrates.  But the part they play  is no  small. They  are  vital  for  the  very  survival  of man because  they  take  part as catalysts  in various body processes. They  protect  the body against  ill_ health, infection  and disease. 

 Some 13 vitamins are stated to be needed by the body. Since the  body cannot manufacture vitamins ( at least in sufficient quantity), they must  be  supplied through the  diet. A  well_ balanced  diet, in most instances,  meets the daily requirement of vitamins  needed by the body. 




Classification  

Vitamins are classified into two  broad  groups as below :

( 1) Fat Soluble Vitamins:

(a) Vitamin A or retinol 

(b) Vitamin D 

(c) Vitamin  E

(d) Vitamin K 

(2) Water Soluble Vitamins:

(a) Thiamine ( Vitamin B1)

(b) Riboflavin  ( Vitamin B2) 

(c) Niacin or Nicotinic acid  ( Vitamin B3) 

(d) Pyridoxine ( Vitamin B6) 

(e) Pantothenic  acid  ( Vitamin B5) 

(f)  Folic acid 

(g) Vitamin B12 

(h) Ascorbic acid  (Vitamin  C). 






VITAMIN  A  (Retinol) 

It was  first fat soluble  vitamin which was  discovered   as  early   as 1913  by Mc  Collum. Paul Karrer succeeded  in determining  the structure  of carotene  and  vitamin   A  and was thus the  first person to describe  the structure  of   a vitamin. For  these discoveries  Prof. Karrer  was awarded  the Nobel Prize for chemistry  in 1937  together  with W. Norman  Haworth .


  Vitamin   A is a fat _ soluble  vitamin. It's  chemical  name is " retinol". Surveys carried out by the National Institute  of Nutrition  in  Hyderabad  ( India) indicate that 8 per cent of children  between the ages 6 months and 6 years had vitamin A deficiency  signs. In some countries, including  India, Vitamin A is a major cause of preventable blindness.  

Functions  

The functions  of vitamin A are still not well understood . The known functions are :_ 

(1)  It is  needed  for normal  vision, and health  of the eyes. 

(2)  It is needed for the health  of the epithelial  tissues  ( e.g., skin, mucous membrane) of the body.

(3)  It is connected  with growth, especially  skeletal  growth. 

(4) It is anti _ infective, i.e., it protects the body against  microbial  infection. 




Sources :


Vitamin  A is widely distributed  in animal and plant foods _ in animal foods as performed  vitamin  A ( retinol), and in plant foods as provitamins  ( carotene).

 (a) ANIMAL  FOODS :  Foods  rich  in  retinol  are liver, eggs,  butter, cheese, whole  milk, fish  and  meat. Fish   liver  oils are the  richest  natural   source  of retinol, but they are  generally  used  as nutritional  supplements  rather  as  food  sources. 


( b) PLANT   FOODS   :  The   cheapest  source  of vitamin  A is green leafy  vegetables  such as spinach  and  amaranth  which  are found  in  great  abundance  in nature  throughout the year. The  darker the green  leaves,  the higher  its   carotene   content. Vitamin  A  also  occurs  in most green  and  yellow  fruits  and  vegetables (e.g.,  papaya, mango, pumpkin)  and in some roots  (e.g., carrots). The most  important  carotenoid  is beta_ carotene  which  has the highest  vitamin A  activity. Carotene  are converted  to vitamin A in  the small  intestine. This  action  is poorly accomplished  in  malnourished  children  and those suffering from  diarrhoea. 


(c) FORTIFIED  FOODS :  Foods fortified with vitamin  A  (e.g., vanaspati,  margarine, milk) can be  an  important  source. Vitamin A  content of selected foods  is  as  given 






Daily  requirement 

The WHO in 1967 recommended  that the requirement  of vitamin  A should  be stated in terms of micrograms ( ųg  or mcg) of retinol  instead of " International  units"  ( I.U.).The  international  unit  can be converted into  micrograms  as follows : 

1. I.U. of vitamin  A = 0.3 ųg retinol 

 However  I.U. still continues  to be used as a measure. 

Recommended  allowances 


  The recommended  daily intake  of vitamins  A is 600  micrograms  for adults. The detailed  recommendations are given. The present expert committee of ICMR ( 2010) has modified  the extent of conversion efficiency  of renitol : ß _ carotene  from 1: 4 to 1: 8.










Conversion ratio of 1:8 is used .

Effects of deficiency 

  The specific  effects of vitamin  A  deficiency  are as follows: 

 (1) Night _ blindness : Night _ blindness  or inability  to see in dim light is the earliest symptom of vitamin  A deficiency.  

(2) Xerophthalmia : The word xerophthalmia  means dryness  of the eye. The  white  portion  of the eye ( conjunctiva) becomes " dry" when the eye lids are kept open  for  half a minute or  so.  This  is an  early clinical sign  of vitamin A  deficiency. In addition,  the conjunctiva appears muddy and  wrinkled.

(3) Bitot's spots :These are brownish, triangular,  raised, foamy patches  seen on the white portion  ( conjunctiva) of the eye. 

(4) Keratmalacia : The  cornea ( black portion)  of the eye becomes  soft and loses its transparency. The softening  may affect a part or whole of  the cornea. If not  promptly  treated, it leads to complete collapse  or destruction  of the eyeball,  resulting  in blindness . Once  this  stage is reached,  no amount  of rich food or treatment  can being back the eye_  sight.  

Storage  

 Vitamin  A, taken  in excess, can be stored in the  liver  for some months. Studies have shown that  if  a pregnant mother is given vitamin A supplements during  the last 100 days of her pregnancy , the child born to her will have better stores of vitamin A  in the liver . The baby has less risk of developing  vitamin A deficiency  than its counterpart. Further the level of vitamin A in breast milk of such mothers will be fairly high. 

However,  excess intake of vitamin A for  longer periods may be toxic. It may show itself  in such  symptoms  as headache, drowsiness, vomiting  and extensive peeling  of the skin. The optimum daily requirement  of vitamin  A 

Vitamin  A and blindness  


Prevention 

Prevention  and  control of blindness  takes two forms _ 

(a)  improvement  of people's  diet so  to ensure a regular  and  adequate  intake  of foods rich  in  vitamin A, and 

(b) Reducing  the frequency  and severity  of contributory factors, e.g., PEM, respiratory  tract infections, diarrhoea  and measles . Both are long term measures  involving  intensive nutrition  education  of the public and community  participation. 

 Since vitamin  A can be stored in the body for 6 to 9 months  and liberated  slowly,  a short term, simple technology  had been evolved  by the National Institute  of Nutrition  at Hyderabad ( India) for community  _ based intervention  against  nutritional  blindness . The strategy  is to administer  a single massive  dose of 200,000 I.U. of vitamin  A  in oil  ( retinol palmitate) orally every 6 months to pre_ school children  (1 year to 6 years), and half that dose ( 100,000  I.U.)  to children  between  6 months and one year of age. In this way, the child would be, as it were " immunized " against  xerophthalmia. 

   The Government  of India in 1970 launched  a National Vitamin  A Prophylaxis   programme  for the prevention  of blindness  in children  in endemic  states. The programme  is continuing  as part of RCH services . Under the programme, the first dose of 1 lakh units of  vitamin   A is given  at age  nine months  alongwith   measles  vaccination.  The second  dose ( 2 lakh units) is then given after 9 months. Subsequent  doses of 2 lak  units are given at six months intervals  upto 5 years of age. 

VITAMIN  D

Vitamin D occurs in many forms, but the important ones from the  point of human nutrition are: 

(1) Vitamin  D2  or    ergocalicifrol 

(2)  Vitamin  D3  or cholecalciferol 

 Vitamin  D2 or ergocalciferol does not occur in nature. Vitamin D3 occurs  widely in animal fats and fish  oils . It  is also  formed from 7 __ dehydrochesterol in  the   human skin  by  exposure  to sunlight. 


Functions 

(1)  Vitamin   D  is required  for the formation  of the  healthy  bones and teeth.  It  has  a direct action  on the  mineralization   of  bones. 

(2) It  promotes the intestinal  absorption  and utilization  of  calcium  and   phosphorous.

Sources  


(1) Sunlight  : This is an important  nature source  of Vitamin D, especially  in India. The provitamin, 7  _  dehydrochesterol,  which is normally  present  in  the skin  is converted  into vitamin D3 by the action  of  the ultraviolet   rays  of  the sunlight.  The rate at which vitamin  D3  is synthesized  in  the skin depends  upon  the exposure  of the  body  to the sun, and  the amount of pigment  ( melanin) in the skin. The heavier the pigment, the lesser the synthesis.  


(2)  Foods  : Vitamin  D occurs  only in foods of animal origin. Liver, egg yolk, butter and cheese, and some  species  of fish contain useful amounts. Fish liver oils, although not considerd  to be a food, are the richest  source of vitamin D. Other  sources of vitamin  D are foods  artificially fortified  with vitamin D, such as milk, margarine, vanaspati  and infant foods. Dietary  sources of  vitamin D .








Daily  requirement  

(1) Adults : Adults need 2.5 micrograms (100 I.U.)  per  day. In most  climatic conditions , normal adults obtain  vitamin  D  in  enough amounts by exposure  to sunlight. 

(2) Pregnancy,  lactation  and growing  children  : The need  for  vitamin D is considerably  increased during pregnancy, lactation  and  growth.  This may be upon 10 micrograms ( 400 I. U.) per  day. 

  Vitamin  D  is stored in the body. So,  if  taken in excessive  amounts, it can produce toxic symptoms  ( hyper_ vitaminosis  D). It may manifest  itself  in  such  symptoms as nausea, vomiting , loss  of appetite,  excessive  urination,  etc.  In cases of extreme toxicity,  soft tissues like kidneys,  lungs and heart can be calcified  leading  to death. 

Deficiency 

(1)  Rickets : Vitamin  D deficiency  leads to rickets, which is usually  observed  in young  children  between  the age of six months and two years. There is reduced  calcification  of growing  bones. The disease  is characterized by growth failure, bone deformity,  muscular hypotonia, tetany  and convulsions  due to hyper_ calcaemia. There is an elevated concentration  of alkaline  phosphate  in the serum. The bony deformities include curved legs, deformed pelvis,  pigeon chest, Harrison's  sulcus, rickety    rosary,    kyphoscoliosis,  etc.    The  milestones  of  development  such  as walking  and  teething  are delayed. 


(2) Ostomalacia : In  adults, vitamin  D deficiency  may result  in osteomalacia  ( which  means  softening  of  the bones)  which  occurs  mainly  in women, especially  during  pregnancy  and lactation  when  requirements  of vitamin  D  are increased.

Both  rickets and  osteomalacia are frequently  reported  in India, although  they do not appear  to be a problem  of public health important. In the world  as a whole, their prevalence  has declined  as a  result of changes in social  customs  ( e.g., purdah system),  and  the expansion  of mother  and child  health services leading  to better care and feeding  of  infants  and children. 

Prevention   

   Prevention  measures  include 

(a) Educating  parents to expose their children regularly  to sunshine; 

(b) Periodic  dosing  ( prophylaxis)  of young  children with  vitamin  D; 

(c) Vitamin  D  fortification  of  foods, especially  milk. Some  industrialized countries still carry  out  the last  measure . Periodic dosing  and  education  appear  to be the most practical  approaches  in developing  countries. 

VITAMIN   E

 Vitamin  E   (tocopherol)    is widely  distributed   in foods. It is  available in  small quantities  in meats, fruits and vegetables.  By far  the richest  sources  are vegetable  oils (e.g., oils  of sunflower  seeds, cotton  seeds, safflower  seeds). Since  vitamin   E  is available  in many  foods,  humans  on balanced diet  do not  easily   suffer  from  its deficiency. In fact, the role  of vitamin  E in human  nutrition has not  so far  been  established.  The usual   plasma level of vitamin  E in adults is between  0.8 and 1.4 mg per 100 ml. While  there is no doubt  that man  requires  tocopherol  in  his  diet, there is no clear  indication  of dietary  deficiency.  The role  of vitamin  E  at the molecular  level is little  understood. The  current  estimate  of vitamin E requirement  is  about 0.8 mg/ g   of  essential fatty  acids. This roughly  works  out  to 8__ 10 mg   tocopherol  per  day  depending on  the edible  oil used. In animals, deficiency of vitamin E is associated  with  habitual  abortion, testicular  and  myocardial  degeneration. 




VITAMIN  K

There are three  derivatives  of vitamin K: Phylloquinone  (K1), menaquinone (K2) and menadione (K3). Phylloquinone ( k1) is the major   form  of vitamin  K, Antihaemorrhagic  vitamin,  ' Coagulation Factor'  Vitamin 

Dam   and Dosiy got  the 1943 Nobel Prize  for chemical  nature of vitamin K. 

Sources:

Alfalfa  grass ( a clover   _ like  plant used  for fodder),  spinach,  cauliflower , cabbage,  tomato, soybeans,  wheat bran, wheat   germ, whole  wheat, vegetable  oils,  liver,  pork, fish. It is synthesized  by bacteria   in   the large intestine  (colon). Infact vitamin  K1  is abundant  in  vegetable oils,  leafy  green  vegetables and wheat   bran .  Vitamin  K2 is synthesized  by  the intestinal  bacteria.  

Functions 


Vitamin  K occurs in  (1) Fresh  green vegetables and (2) Fruits. It is also synthesized  to some extent by intestinal  bacterial. This vitamin is necessary  for proper clothing  of blood. It is used therefore, for the prevention  and treatment  of bleeding. Vitamin K is also given  to patients  if they  are known  to suffer  from  defects of absorption  due to lack of  bile salts or other types  of malabsorption.  Deficiency  of vitamin  K rarely  occurs in adults  who consume  normal  balanced diets. 

 The vitamin K requirement of man is met by a combination  of dietary intake and microbial synthesis  in  the gut. The daily requirement for man appears  to be about 0.03  mg/ kg  weight for the adult. Newborn infants tend to be deficient in vitamin K due to minimal  stores of prothrombin at birth  and  lack of an established  intestinal  flora. Soon after  birth, all infants, or those at increased  risk, should  receive  a single intramuscular  dose of a vitamin  K preparation  (0.1_ 0.2 mg  of menadione sodium bisulphite dose of a vitamin  K preparation  (0.1_0.2 mg  of  menadione  sodium bisulphite  or 0.5 mg  of  vitamin K1) by way of Prophylaxis.  




B GROUP OF  VITAMINS 





THIAMINE (B1) 

Thiamine or vitamin  B1 is a water_ soluble  vitamin. It is an important  member  of  the B_ group of vitamins.  It is relatively  stable  to heat, but is destroyed  in  neutral  or alkaline  solution. 

Functions 


(1) Thiamine plays an important  part in carbohydrate metabolism . In thiamine deficiency, there is accumulation of pyruvic and lactic acids in the tissues and body fluids. 

(2) Thiamine is also  essential for the  proper functioning  of the nervous  system. 

Sources


  Thiamine  is widely  distributed  in small  amounts  in all natural foods. The richest sources are unmilled cereals, pulses and nuts especially  groundnut. The main source of thiamine in  the diet of Indian people is  cereals (e.g., wheat, rice, which contribute from 60 to 85 per cent of the total supply). Meat, fish,  eggs, vegetables  and  fruits are relatively  poor in vitamin B1. Thiamine content of some  food stuff . 







Losses 

Thiamine is readily  lost from  cereals during the process of washing  and cooking . The milling of rice results  in considerable  loss of thiamine. On the other hand, parboiled and home_ pounded rice are better sources. Thiamine  in fruits and vegetables  is partly  lost during prolonged  storage. 

Daily  Requirement 

 Dialy requirement of thiamine  is 0.5 mg per 1000 kcals of energy intake. The body content of thiamine is placed at 30  mg, and if  more than is given it is merely lost in the urine. patients  on regular haemodialysis should  routinely  be given supplements of thiamine. Thiamine  should  also be given prophylactically  to people with persistent  vomiting or prolonged  gastric aspiration and those who go on long fasts. 

Deficiency 

The two principal deficiency  diseases are beriberi  and Wernick's  encephalopathy.  Beriberi may occur in three main forms: 

(a) The dry form characterized by nerve involvement  (peripheral  neuritis); 

(b) The wet form   characterized  by heart involvement  (cardiac beriberi); and 

(c) infantile beriberi,  seen in infants between  2 and 4  months  of  age. The affected  baby  is usually  breast_ fed  by a thiamine  _ deficiency   mother  who commonly  shows signs  of peripheral  neuropathy.  Wernick's  encephalopathy  ( seen often  in  alcoholics) is characterised by ophthalmoplegia, polyneuritis, ataxia  and mental  deterioration. 


    Beriberi  can be  eliminated  by educatng people  to eat  well_ balanced , mixed  diets  containing  thiamine _ rich  foods  (e.g., parboiled  and undermilled  rice) and to stop all alcohol. Direct supplementation  of high_ risk  groups ( e.g., lactating  mothers) is another approach.  

RIBOFLAVIN (B2) 

Riboflavin  ( Vitamin B2) is  a member  of the B_ group vitamins. It  has  a fundamental  role in cellular  oxidation.  It plays  an  important  role  in maintaining  the integrity  of mucocutaneous structure. It is a co_ factor in a number  of enzymes involved  with energy metabolism. 

Sources 

Its  richest  natural sources are milk, eggs, liver, kidney and green leafy vegetables. Meat and fish contain small amounts. Cereals ( whether whole or milled) and pulses are relatively  poor sources but because  of the  bulk in which they are consumed , they contribute  much of the riboflavin to  India  diets. Germination  increases  the riboflavin content of pulses and cereals. The riboflavin  content of some common foods .








Deficiency 

The most common lesion associated  with riboflavin  deficiency  is angular  stomatitis. Other clinical signs suggestive  include  cheilosis, glossitis, nasolabial dyssebacia etc . Riboflavin Deficiency  almost always occurs in association  with deficiencies of other B-comolex vitamins.

Requirement 

There are no real body stores of riboflavin . Daily requirement  is 0.6 mg per 1000 kcal of energy intake . 

NIACIN (B3)

Niacin or nicotinic acid (B3) is essential  for the metabolism of carbohydrate, fat and protein.  It is also essential  for the normal functioning of the skin, intestinal and nervous systems. This vitamin differs from the other vitamins  of the B-comolex group in that an essential  amino acid, tryptophan serves  as its precursor. 

Sources 

 Foods  rich in  niacin  and / or tryptophan  are liver, kidney  meat, poultry, fish,  legumes and  groundnut. Milk  is a  poor  source of  niacin  but its protein are rich in tryptophan  which is converted  in  the body into  niacin ( about 60 mg  of niacin). In many cereals, especially  maize, niacin  occurs in  " bound" form unavailable  to the consumer. 

Deficiency

Niacin  deficiency  results in pellagra. The disease  is   characterized  by three D's __ diarrhoea , dermatitis  and dementia. In  addition glossistis  and  stomatitis  usually  occur. The  dermatitis  is bilaterally  symmetrical  and  is found  only on  those surface  of  the body exposed  to sunlight, such as back of the hands, lower legs, face and neck. Mental  changes  may also occur which   include   depression, irritability  and delirium.  

      
  Pellagra  is  a  preventable  disease. A  good mixed  diet containing  milk  and meat is universally  regarded  as an essential  part of  prevention  and treatment . Avoidance  of total  dependence  on maize  or jowar   ( sorghum) is an important  preventive  measure. Pellagra  is a disease  of poverty.  



Requirement  

The recommended  daily allowance  is  6.0 mg/ 1000 kcal of energy  intake.

PYRIDOXINE ( B6)

    Pyridoxine  (vitamin  B6) exists  in three  forms: pyridoxine, pyridoxal  and pyridoxamine.It plays  an  important  role  in the metabolism of amino acids,  fats  and  carbohydrates . It is widely  distributed  in food, e.g., milk, liver, meat, egg   yolk,   fish,  whole  grain  cereals,  legumes  and vegetables . Pyridoxine  deficiency is  associated   with  peripheral  neuritis. Riboflavin  deficiency  impairs  the  optimal  utilization  of pyridoxine . INH, an anti_ tuberculosis  drug is a recognized antagonist, and patients receiving INH are provided  with a supplement of pyridoxine.

   The  requirement  of adults very  directly  with  protein  intake. Adults  may  need  2 mg/ day;  during  pregnancy  and  lactation,  2.5  mg/ day. Balanced  diets  usually  contain  pyridoxine,  therefore  deficiency is rare. 


PANTOTHENIC  ACID (B5) 

 There is a long  standing  evidence  for a relation  between  pantothenic  acid and  adrenal  cortical  function,   in the biosynthesis  of corticosteroids.  Human  blood normally  contains  18_ 35 mg of pantothenic  acid  per  100 ml, mostly present  in the cells as coenzymes  A. The daily  requirement  is set  at 100 mg. All  foods  contribute  to it's  dietary  intake. 

Biotin ( Vitamin H, Vitamin B7) 

Syorgyi   used  the term vitamin  H for biotin  in 1931.

Sources :

Yeast,liver , egg yolk,  tomatoes,  honey. A  large  portion of  the human   biotin   requirement  is supplied  from  the  intestinal  bacteria.  

Functions  

(i)  It may serve  as coenzyme. It plays a key role in  carboxylation (addition   of  carbon dioxide) involving  fatty acids  and various carboxylic  acids).

(ii) It plays  a role in   the deamination   of certain   amino acids. 

(iii) Biotin  plays  a role in the synthesis  of  oleic  acid by certain  lactic   acid producing  bacteria.

Deficiency  Symptoms: Its   deficiency  is caused by prolonged  use of antibacterial  drugs (e.g.,  antibiotics  and  sulpha  drugs)  which reduce  the intestinal  bacterial  flora. Biotin  deficiency  also  occurs by eating  raw  egg  white  in large quantities. Raw  egg white  contains  avidic protein  which prevents the  absorption  of biotin. Egg should not be  eaten   in  raw  state. Biotin  deficiency causes skin lesions poor  growth, loss of muscular  control, loss of appetite,  weakness, hair fall etc. 



          FOLATE  

The  recommended  name  is folare, alternative  name  is folacin  and  the usual  pharmaceutical  preparation  is folic acid. 

  Folic  acid  plays  a role  in synthesis  of nucleic  acids  ( which contribute  to chromosomes). It is also needed  for  the normal development  of blood cells  in  the  bone marrow. 

Sources 


 The name comes from the  latin  folia (= leaf) but foods  such as liver, meat, dairy  products, eggs, milk, fruits and cereals  are as  good  dietary  sources as leafy  vegetables. Overcooking  destroys  much  of folic acid  and  thus contributes  to folate  deficiency  in man. Folate  deficiency  has been reported in babies given milk  foods subjected  to heat sterilization. 

Deficiency  


Folate deficiency   may occur simply  from  a poor diet. It is commonly  found  in   pregnancy  and lactation,  where requirements  are increased.  It results  in megaloblastic  anaemia,  glossitis,  cheilosis and  gastrointestinal  disturbances  such as  diarrhoea,  distension  and flatulence.  Severe  folate  deficiency  may  cause infertility or even  sterility.  There is also  evidence  that  the  administration  of folic  acid  antagonists  (e.g., alcohol, pyrimethamine, and  cotrimoxazole) in early pregnancy may produce a  abortion  or  congenital  malformations. 

Requirement 

Body stores  of  folate  are not  large, about 5_ 10 mg,  and  therefore, folate  deficiency  can develop  quickly.  Folic  acid  requirements  are greatest  in conditions  where there is rapid  cell multiplication,  such as during  growth in young  children  and during  pregnancy  has been  found  to increase  the  birth weight  of infants   and decrease  the  incidence  of low birth weight  babies. Intake  valves  recommended  by ICMR  ( 2010) 

                                                    Per day
(a) Healthy  adults    ....           200 mcg

(b) Pregnancy          ....             500 mcg
 
(c) Lactation            ....             300 mcg 

(d) Children            ....            80_ 120 mcg 


VITAMIN  B12 

Vitamin  B12   is   a  complex  organo___ metallic  compound  with a  cobalt   atom. The  preparation  which  is  therapeutically  used  is  cyanocobalamine. Vitamin  B12  cooperates with  folate  in  the synthesis  of DNA, so deficiency  of   either  leads  to megaloblastis. Vitamin  B12  has  a  separate  biochemical   role, unrelated  to folate, in synthesis  of  fatty  acids  in myelin. The physiological  mechanism for  its absorption  requires  intrinsic  factor  from  the stomach, and  the  complex   is absorbed  only at a special  site  in  the terminal  ileum. 

Sources 

   Good  sources  are liver, kidney, meat, fish, eggs, milk and cheese. Vitamin  B12  is not  found  in  foods  of vegetable origin. It is also synthesized  by bacterial  in colon. Unlike  folic  acid,  vitamin  B12  is relatively  heat  stable. Liver  is  the main   storage   site  of vitamin  B12. About  2 mg   are stored  in liver, and  another  2 mg elsewhere  in  the body. These stores  are sufficient  to tide over  any deficiency  for one  to three years.  Because  of  these reserves,  deficiency  of vitamin B12 appears  to be rare. 

Deficiency  

Vitamin  B12  deficiency  is associated  with megaloblastic anaemia ( pernicious  anaemia), demyelinating  neurological  lesions in the  spinal cord and infertility  ( in animal  species). Dietary  deficiency  of B12 may arise in subjects  who are strict  vegetarian  and  eat  no animal  products. 

Requirement  

Intake  values  recommended  by ICMR  ( 2010) 

                                                     Per day 
(a) Normal    adults    ....           1  mcg

(b) Pregnancy          ....             1.2 mcg
 
(c) Lactation            ....             1.5  mcg 

(d) Infants & Children  ....    0.2  mcg 

Vitamin  B15 ( Pangamic Acid) 

It has been  found  to be present  in  the  seeds  of many  plants  ( hence its   name   from Greek  pan_ all, gamy _ seed).It  helps in  the   utilization of  oxygen  by  the  cells  and promotes  the oxidation  of  alcohol  in the  organism. The compound   is  used  to treat  certain  cardiac  and   vascular  diseases. 

Vitamin  B17 ( Laetrile) :

It has also a member   of vitamin  B complex. Its  source  is  wheat  grass juice. Vitamin  B17 has  anticancer property. 




 

VITAMIN  C (Ascorbic  Acid)

James Lind gave  accurate  description  of  the disease  as early as 1757 . Szent  Gyorgyi in  1928  isolated  substance from adrenal  gland  called  hexuronic acid  which was later  identified  as vitamin  C by Waugh and King (1932) .







Vitamin  C or   ascorbic  acid  is  a water  soluble  vitamin. It  is the most  unstable  of all the vitamins, gets  rapidly  destroyed  by high temperature,  oxidation,  drying  or storage. 

  Vitamin C is  a  potent  antioxidant  and  has  an important role  to play in  tissue oxidation.  It is  needed  for  the formation  of  collagen  which  provides matrix  for the blood  vessels  and connective tissue,  and for the  bones and cartilage. By reducing  ferric  iron  to ferrous  iron, it facilities  the absorption   of iron   from  vegetable foods. 




Sources  

(1) Fruis :  All fresh fruits contain vitamin C .Amla  or the  Indian  gooseberry  is   one of the richest  source, in  the fresh as  well as in  the dry condition. Guavas  are another  cheap but rich  source.

(2) Vegetables  : Vegetables  especially  green  leafy vegetables are rich in vitamin C. Roots and tubers  (potatoes) contain  very  small   amounts.  Sprouting  pulses  are yet  another   source.  

(3) Animal  Foods  :Meat and milk  contain  very  small amounts.  The  dietary  sources  of vitamin C 








Deficiency

Deficiency  of Vitamin  C results in scurvy, the signs  of which are swollen   and bleeding  gums, subcutaneous  bruising  or  bleeding  into  the skin   or joints,  delayed  wound   healing,  anaemia   and  weakness. 

Requirement 

The values  recommended  in India  are as follows :

Adults      ............................... 40 mg per day 

Pregnancy. ............................60 mg per day 

Lactation..............................80 mg  per  day 

Infants and children. .....25_ 40 mg per day

  
 The  recommended  daily  dietary  intake  of fat  soluble  and  water  soluble   vitamins 

Functions: 

No coenzyme relationship  of vitamin  C has been  established 

(i) Vitam C  helps  in   the  formation  and growth of connective   tissues,  cartilages,  bones, teeth, etc. 

(ii)  It  is  necessary  for  healthy  gums  and teeth. 

(iii) Ascorbic  acid  in food helps  in  the absorption  and  utilization  of iron  by  converting  the inorganic  ferric iron  to the ferrous  form. 

(iv) Vitamin  C is  required  for  the normal  function  of  adrenal  glands.  

(v) It is  also essential  for  the formation  of RBCs and the production  of antibodies. Thus it  maintains immune  defence   system.  

(vi)  It  also  maintains  the strength  of the walls of the  bloo capillaries. 

(vii) Vitamin  C helps  in healing  the wounds. 

(viii)  It  has  antioxidant  property. 

(ix) It  helps  in   the synthesis  of  neurotransmitters. 

3. Vitamin  P ( Hesperidin, Citrin, Rutin) 

Sources:

Citrus  fruits, green  vegetables,  Lemon rind ( tough outer layer  or covering) of  fruits  and  vegetables  are good source  of  hesperidin. Buckwheat  ( wild wheat)  leaves  are good source    of   rutin. 

Function : Vitamin  p  useful  for maintaining  resistance  in  the walls of blood capillaries













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