150 BIOLOGY AND HUMAN LIFE 



WHAT TO EAT 



1. Why choice of food must be learned 



Our instincts are not related to the usefulness or the harmfulness 

 of the many things that we can put into our mouths 



There is no necessary connection between the food value of 

 natural objects and their appearance or taste 



There is no necessary connection between contents of natural 

 objects and their possibly poisonous properties or their 

 digestibility 



New plants and animals of food value are constantly being intro- 

 duced from other parts of the world 



New discoveries are constantly being made about the relation of 

 natural materials to the health of the human body 



New discoveries are being made about the influence of cooking, 

 preserving, etc. upon the food value and effects of natural 

 materials 



2. Relation of food to health 



Upkeep of basic metabolism 



Supply of growth material 



Energy for day's work 



Vitamins and mineral activators and regulators 



3. What should influence selection of food (quality) 



Taste ; digestibility ; nutritive value 



4. Daily needs (quantity) 



Nutritive ratio (about 11 per cent of total calories from proteins) 



Age and food needs 



Work and food needs 



Climate or season and food needs 



5. A balanced diet (proportion) 



Importance of enough proteins etc. 

 Disadvantage of excess proteins 

 Sources of malnutrition 



Insufficient food 



Deficiency of particular constituents 

 Protein ; vitamin ; minerals ; energy 



6. Food fads 



Related to ignorance, which is not aware of the facts about 

 protoplasm and its nutrition 



Related to simple-mindedness, which tries to solve a very com- 

 plex problem with a very simple rule 



