94 THE USES OF FOODS 



for example, it has recently been discovered that the 

 beating of the heart, the contraction of working muscles, 

 and the ability of our nerves to send messages depend upon 

 the presence of very minute quantities of calcium, magne- 

 sium, potassium, and phosphorus in the body. 



Two uses of foods. Scientists have shown us that our 

 common foods are made up of substances called nutrients. 

 These nutrients are known as proteins, fats, carbohydrates, 

 mineral matter, and water. Three of these nutrients, 

 protein, fat, and carbohydrate, are consumed in the body 

 to release energy. The mineral matter serves to aid in the 

 making of bone, in carrying on digestion, and in other body 

 functions, while the water is largely used as a vehicle to 

 carry the nutrients, and forms a very large percentage of 

 the human body. Protein, of which eggs, lean meat, and 

 the germ or gluten of wheat are examples, is used for mak- 

 ing body material. The following table taken from a 

 government bulletin l sums up the uses of the nutrients to 

 man. 



THE FUNCTION OF THE NUTRIENTS IN THE BODY 



Protein Forms tissue (muscles, 



White of eggs (albumen), tendon, and probably 

 curd of milk (casein), fat), 

 lean meat, gluten of 

 wheat, etc. 



Fats Form fatty tissue. 



Fat of meat, butter, olive 



All serve as fuel and 

 yield energy in form 

 of heat and muscular 

 strength. 



oil, oils of corn and 

 wheat, etc. 



Carbohydrates Transformed into fat. 



Sugar, starch, etc. 

 Mineral matter (ash) . . Aid in forming bone, as- 

 Phosphates of lime, pot- sist in digestion, in ab- 

 ash, soda, etc. sorption and in other 

 ways help the body 

 parts do their work. 



Water is used as a vehicle to carry nutrients, and enters into the composition of liv- 

 ing matter. 



1 Adapted from Atwater, Principles of Nutrition and Nutritive Value of 

 Food, U. S. Department of Agriculture, 1902. 



