Proper Nutrition 139 



this time a carefully balanced diet is very es- 

 sential. 



The great variety of articles in use as food 

 all contain only a few essential principles, 

 — proteins, mineral matter, fats, carbohydrates 

 and water, the latter constituting a large pro- 

 portion of all foods. These different substances 

 when taken into the body have various functions 

 to perform. The proteins and mineral matter 

 are used in the growth and repair of the body ; 

 the fats supply heat and energy and are de- 

 posited in the tissues for form and contour; 

 the carbohydrates also supply heat and energy, 

 and may be changed into fat in the system ; the 

 water gives bulk and solvent properties to the 

 various tissues. 



These food principles are found in a variety 

 of foims and combinations. Protein exists as 

 lean meat, the curd of milk, fish, poultry, eggs, 

 cheese, beans, barley, oatmeal and the gluten 

 of flour. The mineral matter consists largely 

 of earthy salts, such as phosphate of lime and 

 compounds of magnesium, sodium, potassium 

 and iron. These substances are usually taken 



