274 FOODS AND DIETARIES 



ing up or repairing tissue. It is certainly true that in both plants 

 and animals such foods pass directly, together with foods contain- 

 ing nitrogen, to repair .waste in tissues, thus giving the needed 

 proportion of carbon, oxygen, arid hydrogen to unite with the 

 nitrogen in forming the protoplasm of the body. 



Inorganic Foods. Water forms a large part of almost every 

 food substance. It forms about five sixths of a 'normal daily diet. 



The human body, by weight, is 

 about two thirds water. About 90 

 per cent of the blood is water. 

 Water is absolutely essential in 

 passing off waste of the body. 

 When we drink water, we take 

 with it some of the inorganic salts 

 used by the body in the making of 

 Three portions of foods, each of bone and in the formation of proto- 

 which furnishes about the same lasm Sodium chloride (table 



amount ot nourishment. 



salt), an important part of the 



blood, is taken in as a flavoring upon our meats and vegetables. 

 Phosphate of lime and potash are important factors in the forma- 

 tion of bone. 



Phosphorus is a necessary substance for the making of living 

 matter, milk, eggs, meat, whole wheat, and dried peas and beans 

 containing small amounts of it. Iron also is an extremely impor- 

 tant mineral, for it is used in the building of red blood cells. Meats, 

 eggs, peas and beans, spinach, and prunes, are foods containing 

 some iron. 



Some other salts, compounds of calcium, magnesium, potassium, 

 and phosphorus, have been recently found to aid the body in many 

 of its most important functions. The beating of the heart, the 

 contraction of muscles, and the ability of the nerves to do their 

 work appear to be due to the presence of minute quantities of these 

 salts in the body. 



Uses of Nutrients. The following table sums up the uses of 

 nutrients to man : l 



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

 U.S. Department of Agriculture, 1902. 



