FOODS 67 



They contain carbon, hydrogen, oxygen and nitrogen, together 

 with, usually, a small quantity of sulphur and phosphorus. 

 They occur in the form of casein in milk and cheese, myosin and 

 syntonin in muscle, vitellin in the yolk of eggs, glutein in flour, 

 legumin in peas, beans and lentils, and in some other forms. 

 Proteids may be used by the body to produce heat and energy, 

 but being more stable in composition than carbohydrates and 

 fats, they are more often used to build up tissue. In fact the 

 proteids are absolutely essential to life while this is not true of 

 carbohydrates and fats, since the proteids must be used to build 

 up new cells to take the place of those being constantly worn out 

 and eliminated. 



The animal foods which are richest in proteids are lean meat, 

 milk, eggs, cheese and all kinds of fish, while the vegetable are 

 wheat, beans, peas and oatmeal. It has been found that the 

 animal proteid foods are split up and digested much more 

 easily than are the vegetable. Hence the great majority of the 

 people rely upon the animal foods for their supply of proteid 

 material which is necessary to life. 



The composition of a few of the more important articles used 

 as food is shown by the following tables.* 



Milk: Woman, Cow, 



Per cent. Per cent. 



Protein (chiefly caseinogen) 1.7 3.5 



Butter (fat) 3.4 3.7 



Lactose 6.2 4.9 



Salts o . 2 0.7 



Eggs: 



Total amount of solid 13 .3 per cent. 



Protein 12.2 per cent. 



Sugar 0.5 per cent. 



Fats ) 



Lecithin | Traces. 



Cholesterin J 



Inorganic salts 0.6 per cent. 



*These tables are taken from Halliburton's Handbook of Physiology. 



