FOOD AND DIGESTION 93 



as well as a tissue builder. We could burn beans and 

 peas as well as the strictly fuel foods, starch and fat, in 

 an engine, and get heat to move the engine. If one takes 

 up athletics or hard physical labor, he should increase the 

 amount of fats and carbohydrates eaten, but not of proteid. 

 Muscular activity increases the carbon waste but not the 

 nitrogen waste of the body. 



Minerals. — The iron of the blood and the mineral salts 

 in bone (carbonate and phosphate of lime) must enter the 

 body in organic form in order to be used. Water and salt 

 are mineral foods. The body is about two thirds water. 

 The cells must do their work under water. They cannot 

 live when dried. Water enables the blood to flow ; and 

 the blood is not only the feeder, but also the washer and 

 cleanser of the tissues. Some persons get out of the habit 

 of drinking plenty of water, and their health suffers thereby. 

 In such a case drinking plenty of water will be safer and 

 more effective than taking poisonous drugs to restore health. 



Adulteration of Food. — Sometimes cheaper materials, of 

 little or no value as food but of no great injury to health, 

 are added to foods. Examples: water added to milk, 

 sawdust to ground spices, chicory to coffee, glucose to 

 maple syrup. Other f,orms of adulteration not only cheat 

 the purse but tend to destroy health, or actually do so. 

 Examples: Boracic acid or formalin added to milk to 

 prevent souring, copper to canned peas, etc., to give a 

 bright green color ; salicylic acid or borax used in minute 

 quantities as a preservative with canned corn, tomatoes, 

 etc.; acids added to "apple" vinegar; dried fruit treated 

 with sulphur to prevent a dull color. Pure food laws tend 

 to repress these evils. It is best to buy foods in their 

 original form. For instance, lemons are more reliable 

 than vinegar. A bit of lemon at each plate, in house- 



