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Sunday, April 29, 2012

Nutrients and Their Functions

Carbohydrate:

Carbohydrates (sugar and starches) are the most efficient sources of energy and are known as the “fuel of life.”  They are abundantly found in most plant food sources. Complex  carbohydrates  (starches)  are  in breads,  cereals,  pasta,  rice,  dry  beans  and  peas,  and other vegetables, such as potatoes and corn. Simple carbohydrates are found in sugars, honey, syrup, jam, and many desserts. 

Each gram of carbohydrate yields 4 calories in the process  of  its  metabolism.   

The main functions of carbohydrates are to

  • furnish   the   main   source   of   energy   for muscular work and nutritive processes,        
  • help maintain body temperature,
  • form reserve fuel,
  • assist in oxidation of fats, and
  • spare protein for growth and repair.

Protein:

Proteins are the “building blocks” of the body and provide   important   required nutritive   elements.

Proteins   are   needed   for  

  • growth, maintenance,   and replacement of body cells, and
  • they form hormones and enzymes used to regulate body processes.  

Extra protein is either used to supply energy or is changed into body fat.    Found in both the animal and plant kingdoms, all proteins are composed of amino acids. Some amino acids are absolutely essential to maintain life and are necessary for repair, growth, and  body development. Of the approximately 20 amino acids, our body can produce all but nine. These nine amino acids are termed “essential amino acids.”  We must get them from food, and we need all nine at one time so our body can use them effectively.

Each gram (g) of protein yields 4 calories in the process of metabolism.

Fats:

The chief functions of fats are to supply energy and transport fat-soluble vitamins.


Each gram of fat yields 9 calories. 


Fats provide the most concentrated source of  calories  (and,  therefore,  energy)  of  all  the  food nutrients.

Fats  are  found  in  both  the  animal  and vegetable kingdoms.   Fatty acids and glycerol are the end products of the digestion of fats.

Many  fats  act  as

  • carriers  for  the  fat-soluble vitamins  A,  D,  E,  and  K.    
  • a padding for vital organs, particularly the kidneys, and as subcutaneous tissue to help conserve body heat. 
  • Fat is  stored  as  adipose  (fatty)  tissue  to  form  a  reserve supply  in  time  of  need.

Dietary  fats  delay  gastric  emptying and promote a feeling of fullness.   Excess calories from fats may produce obesity, the forerunner of arteriosclerosis, hypertension, gallbladder disease, and diabetes. A diet high in fat, especially saturated fat and   cholesterol,   contributes   to   elevated   blood cholesterol levels in many people. 

Minerals:

Although mineral elements constitute only a small portion  of  the  total  body  weight, they  enter  into  the activities  of  the  body  to  a  much  greater  degree  than their weight would indicate.  Certain mineral elements are essential for specific body functions. While it is not yet known exactly how many of the mineral elements are  indispensable  to  the  body  functions,  seemingly small changes of mineral concentration can be fatal.


  • These   essential   inorganic   elements   contribute overwhelmingly to the skeletal framework of the body and   teeth,   and   they   are   an   essential   part   of   many organic compounds.
  • Minerals   form   an   integral   part   of   basic   cell structure   and   circulate   in   body   fluids.
  • They   also exercise   specific   physiologic   influences   on   the function of body tissues.  

For mineral needs to be met satisfactorily,  consumption  of  each  element  must  be sufficient  to  cover  body  tissue  requirements  and  to meet  changing  physiological  needs.   

Vitamins:

Vitamins are essential compounds that are present in food in minute quantities. 

  • Although vitamins do not furnish energy or act as tissue-building materials, they do act  as  catalysts  in  many  body  chemical  reactions and  are  necessary  for  normal  metabolic  functions, growth,  and  the  health  of  the  human  body.
  • Their absence results in malnutrition and specific deficiency diseases.

Vitamins are so widely distributed in food that a properly   prepared   normal   diet   usually   provides   an adequate amount

Water:

Water is sometimes included in a listing of nutrients
§  involved in most chemical reactions in the body
§  a major component of the blood
§  serves many other functions


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