The body contains about  50 minerals, all of which must be obtained from the foods we eat. Many of  these  are widely  distributed in food stuffs  so that  a well _ balanced  diet  will supply them in  the amounts  needed by the body. 

   Minerals  may be classified  into  2 broad groups: 

(1)  Major minerals : These are calcium,  phosphorus,  sodium, etc.

(2). Trace _ elements  : These  are required  in micro_  quantities,  e.g., iodine,  fluorine, zinc,  cobalt,  etc.


(1)Formation  of hard  structures: Certain minerals, such  as   calcium, phosphorus  and magnesium are required  for the formation  of hard  structures, e.g., bones  and teeth. 

(2) Physiological role : Some  minerals are found  in body  fluids  and  play a physiological  role and maintain osmotic pressure. 

(3) Specific  function: Some are required  for a specific  purpose,  for example, iron is required  for blood  formation. 

  A brief  account  of the  important  minerals needed  by the body 


Calcium   is  a major  mineral  element  of  the body. It forms 1.5 to 2 per cent of  the body weight.  That  is, the body of an adult  person may  contain  850   to  1,400 grams  of calcium . About  98  per  cent  of  the calcium in   the  body  is  found  in    the bones.  Calcium  is   present  in   the blood also _ about 10  mg. per 100 ml.


Ionized  calcium  in the plasma has many vital functions  including  formation  of bones and teeth, coagulation  of  blood, contraction of  muscles,  cardiac  action, milk production, relay of electrical   and  chemical    messages that  arrives  at a cell's surface  membrane. 


Calcium   is  readily   available  from  many sources. By  far  the best  natural sources  are milk  and milk  products,  (e.g., cheese, curd, skimmed  milk  and butter  milk), eggs  and fish. A litre of cow's   milk  provides  about 1200 mg of calcium,  and human milk  about 300 mg. Calcium  occurs   in milk  as calcium  caseinogenate which  is readily  assimilated  by the body. The cheapest  dietary sources are green leafy  vegetables,  cereals  and  millets  particularly   " ragi" . The limiting  factor in  the  complete  absorption  of calcium   from green  leafy vegetables ( e.g., spinach,  amaranth) is the presence  of oxalic  acid   with    which  calcium  forms  an insoluble  compound,  calcium  forms  an  insoluble  compound,  calcium  oxalate  which interferes   with  the  absorption  of calcium.  The   absorption  is  also  decreased  by  presence  of phytates  and  fatty   in  the diet, and enhanced  by vitamin D. 


It has been  established that if the intake  of vitamin D   is adequate,  the problem  of rickets and  osteomalacia  do not arise even  with low calcium  intake. 


The recommended intake  for an adult is 600 mg per day. During pregnancy  and  lactation, an allowance of 1200 mg has been  recommended. 


The  total  amount of iron  present  in  the body is estimated  to be between  3 to 4 grams, and 60_ 70 per cent  of  this   amount   is found   in   blood. 


Iron is required   for  the formation  of  haemoglobin,  brain   development  and   function,  regulation   of body temperature,  muscle  activity  and   catecholamine  metabolism. Lack   of  iron   directly  affects  the  immune   system. The  central  function of  iron in   the  body  is  " oxygen   transport" and  cell respiration. 


Iron   is present  in both animal  and vegetable  foods. Iron   present in animal  foods (e.g. liver, kidney,  meat, egg,  yolk) is better  absorbed  than iron  in vegetables  (e.g., cereals,  pulses, leafy  vegetables,  nuts, oilseeds, jaggery  and dry  fruits. They  are  important  sources  of  iron  in  the   diets of  a large   majority  of Indian  people. 


Iron is mostly  absorbed from  duodenum  and upper small intestine in the ferrous state, according  to body needs. The rate of iron  absorption is  influenced by a great many factors  like  iron   reserves  of  the subjects,  the presence  of inhibitors (e.g.,phosphates ),  and  promoters (e.g., ascorbic  acid   and  ascorbic  acid_ rich foods)  of  iron  absorption , and  disorders of  duodenum and  jejunum  (e.g.,  coeliac  disease, tropical  sprue). 

Iron  losses 

The total  daily  iron  loss  of an adult  is  probably  1 mg, and  about  2 mg  in   menstruation women. Major  routes  of iron loss are : 

(a) Through haemorrhage,  that is, wherever  blood  is  lost,  iron   is lost, the  causes  of  which   may be   physiological  (e.g., menstruation, childbirth) or  pathological (e.g., hookworms, malaria,  haemorrhoids, peptic   ulcer) ;  

(b)  Basal  losses , such  as  excretion  through  urine, sweat  and bile, and  desquamated surface cells. 

Iron deficiency 

Iron deficiency results in nutritional anaemia, which is  not  a disease  entity. It is rather    a  syndrome  caused  by malnutrition  in   its  widest  sense. Besides  anaemia,  there may  be  other functional  disturbances  such  as   impaired cell _ mediated  immunity,  reduced  resistance  to infection, increased  morbidity  and  mortality  and   diminished  work performance. 

Daily requirement 

 The  values  recommended  in India  are as follows  :

Adult men ..............17 mg  per day 

Adult  women ....... 21 mg per  day 

Pregnancy  ............35  mg per  day 

Lactation............... 21 mg   per   day 


Sodium   occurs   in many  foods, and  is also added  to food during  cooking. Sodium   is   present  in   all body  fluids  and is  lost from  the   body  by  urine  and sweat.  Depletion  of  sodium    chloride    causes  muscular  cramps.  The  daily   requirement  of sodium  chloride   is about   5 grams  for  adults.  The  requirement  depends  upon  climate,  occupation  and physical  activity.  A  strong  relationship  between  hypertension and dietary  salt  intake  has  been  observed  and  intake  of more   than  10 grams  per  day  is considered  to have   definitive    tendency  to  raise blood  pressure. 


Phosphorus  is  essential  for  the  formation  of bones  and  teeth.  It  plays  an important  part in  all metabolisms. It is  widely distributed  in  foodstuffs;  its  deficiency  rarely  occurs. The   requirements  of  calcium  and phosphorous are  considered  together  as their  function  and requirements  are  closely  linked. It  is  suggested  that an  elemental  calcium  phosphorus  ratio of 1:1  may  be  maintained  in most age  groups,  except  in infancy  where the ratio  suggested is 1:1.5 



The adult  human  body  contains  about 250g of  potassium. Potassium   occurs  widely  in foodstuffs,  so   there   is  little  likelihood  of   its    deficiency . Potassium  is  vaso_ active,  increases blood  flow and sustains  metabolic  needs  of  the  tissue. Potassium  supplements  lower  blood pressure,  although  the  response is slow. Diets high in  sodium  and low  in potassium  have been  implicated  in  the  aetiology  of high blood  pressure. The  ideal  desirable  sodium  to potassium  ratio  in   the diet is 1:1  (in  nmol). 


Magnesium is a constituent  of  bones,  and   is present  in  all body cells. Human  adult body  contais  about  25  g of   magnesium  of  which about  half  is  found  in   the skeleton. It appears  that magnesium  is essential   for   the normal  metabolism of calcium  and  potassium. Magnesium  deficiency  may occur in   chronic alcoholics, cirrhosis  of liver, toxaemias  of  pregnancy,  protein _ energy  malnutrition  and malabsorption syndrome.  Magnesium requirement is   estimated  to be about   340 mg/ day  for  adults. 


A group of minerals are required  by  the body in traces or microquantities  _ these  are called " trace elements ". Under  this  heading  are included  iodine, fluorine, zinc, copper, cobalt etc. The functions   of  many  of  these elements  are not completely  understood .Man is not  likely  to suffer   from  trace  element  deficiency , as  long as his diet  is   well_ balanced. 


Iodine is  a  trace element. It is required for the formation  of  thyroid  hormones, thyroxine (T4)  and  triiodothyronine (T3), which is  a hormone  of  the thyroid gland. Iodine  is essential  in minute amounts for normal growth and  development, and well_ being  of humans. 


The best sources  of iodine are sea foods  (e.g., sea fish, sea salt) and cod liver oil. Smaller amounts  occurs in other foods, e.g., milk, meat, vegetables,  cereals, etc. The Iodine  content of fresh water  is small and very variable, about 1_ 50 micrograms/ L.

 About  90 per cent  of iodine comes from foods eaten; the remainder from drinking  water. The iodine content  of  the soil determines its presence  in both water and locally  grown foods. The deficiency   is geochemical  in nature. 


" Goitrogens ", are chemical substances  leading  to the development  of goitre. They interfere with iodine  utilization  by the thyroid  gland. They may occur in food and water. The brassica group of vegetables  (e.g., cabbage,  cauliflower) may contain goitrogens.


The most obvious  consequence of iodine deficiency  is goitre but recent studies have indicated  that there is a much wider spectrum  of disorders, some of them so severe as to be disabling. They include : 

(a) Hypothyroidism 

(b) Retarded  physical  development  and impaired mental function 

(c) increased  rate of spontaneous  aborption  and stillbirth 

(d) Neurological  cretinism, including  deaf_ mutism ; and 

(e) Myxoedematous cretinism, including  dwarfism and severe mental retardation. To express this state of affairs  more accurately,  the term " endemic goitre", is now replaced  by the term  Iodine Deficiency  Disorders (IDD) to refer to all  the effects  of iodine deficiency  on human growth and development  which can be prevented  by correction of iodine deficiency. 

  Prevention  of  goitre:  The  Government  of India is ensuring  supply of  " iodized salt" i.e., ( common salt mixed  with potassium  iodate)  in place of common  salt throughout   the country. 


 The daily requirement  of iodine  for adults is about 150 micrograms. During   pregnancy  the recommendation is about 250 micrograms  daily. 


 Fluorine  is another important  trace element  required  by the body. It is found  mostly  in bones and teeth. 

Source : The  main  source of fluorine to man is drinking  water. It is also  found in traces  in  many  foods, e.g., sea_ fish,  cheese, tea, 

Effects : Deficiency  of fluorine is associated  with dental caries ; on the other  hand, excessive  intake  gives rise to a condition  called " skeletal  fluorosis " a crippling  disease.  Skeletal  fluorosis is reported  in certain parts of Andhra Pradesh  and Punjab where the drinking  water contains excess of fluoride. 

Requirement: The optimum  level of fluoride in drinking  water is 0.5 to 0.8 mg. per litre. 


Zinc is  a component  of more than 300 enzymes . It is active  in the metabolism  of glucides and proteins  and is required  for the synthesis  of insulin  by the pancreas  and for the immunity  functions . Zinc deficiency  has  been  reported to result in growth failure   and  sexual  infantilism in adolescents, and in  loss of taste and delayed  wound  healing.  

Milder  forms  of zinc deficiency  has been  associated  with low birth weight,  intrauterine  growth retardation and preterm  delivery . Several  studies have indicated  that zinc supplementation  may reduce  the incidence  of  clinical  attacks  of malaria  in children.  Zinc  deficiency  is common  in children  from  developing  countries  due to lack of intake  of  animal foods, high dietary  phytate content, inadequate  food intake  and increased  faecal  losses during  diarrhoea.  Zinc  supplementation  in combination  with oral  rehydration  therapy  has been  shown to significantly  reduce the duration  and severity  of acute  and persistent  diarrhoea  and to  increase  survival  in a number  of randomized  control  trials. Zinc  is widely  distributed  in  food_ stuffs, both  animal and vegetable _ but  the bio_ availability  of zinc  in vegetable foods  is low. Animal foods such as meat, milk and fish are dependable  sources. Suggested  daily  intake  for adults  is 12  mg per  day for men, 10 mg per day for women. 10 mg per day for  children  and 5 mg for infants. Growing  children  and  pregnant  and  lactating  women  need  more. Most human diets provide these amounts. 


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