82 Life and Health 



butter, suet, and lard ; but in many parts of the world 

 various vegetable oils are largely used, as the olive, palm, 

 cotton seed, cocoanut, and almond. 



Weight for weight the fats and oils are more valuable 

 than the carbohydrates as sources of energy, but the latter 

 are more easily digested, and more easily oxidized in the 

 body. An important use of fatty foods is for the main- 

 tenance of the bodily heat. The inhabitants of Arctic 

 regions are thus enabled, by large use of the fat and oil 

 from the animals they devour, to endure safely the severe 

 cold. 



121. Saline or Mineral Foods. The principal mineral 

 foods are water, and the salts of lime, iron, magnesia, 

 phosphorus, sodium, and potash. Except common salt and 

 water, these substances are usually taken only in combina- 

 tion with other foods. 



These saline matters are essential to health, and when 

 they are not present in due proportion nutrition is disturbed. 

 If a dog be fed on food freed from all salines, but otherwise 

 containing proper nutrients, he soon suffers from weak- 

 ness, after a time amounting to paralysis, and often dies in 

 convulsions. 



About two hundred grains of common salt are required 

 daily by an adult, but a large proportion of this is con- 

 tained in the organic food. Phosphate and carbonate of 

 lime are obtained from milk and meats. Both are required 

 for the bones and teeth. The salts of potash, which assist 

 in purifying the blood, are obtained from vegetables and 

 fruits. An iron salt is found in most foods, and sulphur 

 in the yolk of eggs. 



122. Water. Water is present in all foods. It is of 

 use chiefly as a solvent, and while not strictly a food, is 

 necessary to life. It enters into the construction of every 



