300 FOOD AND DIGESTION 



about 25.30 per cent of this nitrogenous body, and twice as much nitrogen as 

 wheat. Nuts also form a very nutritious article of diet. 



Carbohydrate Foods. Bread, made from the ground grain ob- 

 tained from various so-called cereals, viz., wheat, rye, maize, barley, rice, 

 oats, etc., is the direct form in which the carbo-hydrate is supplied in an 

 ordinary diet. It contains starch, dextrin, and a little sugar. It also contains 

 gluten, composed of vegetable proteids, and a small amount of fat. 



TABLE OF PERCENTAGE COMPOSITION OF BREAD AND FLOUR. 



Nitrogenous Carbo- 



matters. hydrates. Fats. Salts. Water. 



Bread 8.1 51. 1.6 2.3 37 



Flour 10.8 70- 8 5 2 1.7 15 



Various articles besides bread are made from flour, e.g., spaghetti, maca- 

 roni, etc. Dextrin and a small amount of dextrose are present in bread, 

 particularly in the crust. 



Vegetables, especially potatoes. They contain starch and sugar. In cab- 

 bage, turnips, etc., the salts of potassium are abundant. 



Fruits contain sugar, and organic acids, tartaric, malic, citric, and others. 



Sugar, chiefly saccharose, used pure or in various sweetmeats. 



Oils and Fats. The substances supplying the oils and fats of the 

 food are chiefly butter, bacon and lard, suet (beef and mutton fat), and vegetable 

 oils. These contain the fats olein, stearin, and palmitin. Butter contains 

 others in addition, while vegetable oils, as a rule, contain no stearin. 



Mineral or Inorganic Foods. The salts of the food. Nearly all 

 the substances in the preceding classes contain a greater or less amount of 

 the salts required in food. Green vegetables and fruit contain certain salts, 

 chiefly potassium. Sodium chloride is an essential food; it is contained in 

 nearly all solids, but so much is required that it has also to be taken as a 

 condiment. Potassium salts are found in muscle, nerve, and in meats gener- 

 ally, and in potatoes. Calcium salts are contained in eggs, blood of meat, 

 wheat, and vegetables. Iron is contained in hemoglobin, in milk, eggs, and 

 vegetables. 



Liquid Foods. Water is essential to life, and from two to two and 

 a half pints a day must be consumed in addition to that taken mixed with 

 solid food. Of the non-alcoholic substances which may be added to it for 

 flavoring purposes, such as tea, coffee, cocoa, etc., the last can alone be con- 

 sidered to have a certain food value, as it contains fats, albuminous material, 

 and starch, the other constituents of such substances being a volatile oil, an 

 alkaloid caffeine, and tannic acid. The food value of alcoholic beverages, 

 which has long been a subject of controversy, as now generally agreed is but 

 slight. Beer, wines, and spirits contain ethyl alcohol, the amount varying 

 from 1.5 to 4.5 per cent in beer to 60 to 80 per cent in spirits. 



