DIETETICS 593 



deficiency of certain amino acids. When vegetable proteins of the sec- 

 ond quality, such as those of peas, beans, lentils, etc., are alone available, 

 much larger amounts are necessary. Such proteins are inadequate in the 

 case of growing children at least, and even in adults it is undoubtedly 

 advisable that other proteins should supplement them. 



To insure safety, therefore, it is almost imperative that the diet should 

 contain proteins of .various sources. If for economic reasons the main 

 source must be proteins of vegetable origin, then some animal protein, such 

 as is contained in milk or meat or eggs, should be added to at least one of 

 the daily meals. When peas and beans are mainly depended on for the 

 protein supply, they should be taken either with milk or one of its prep- 

 arations, or with a thick gravy or sauce made from meat and containing 

 the finely minced meat. This must not be strained off, for if it is, the 

 sauce will contain only the meat extractives but not any of the protein, 

 which is coagulated by the boiling water. Meat extract, in other words, 

 contains no proteins; it is not a food but merely a condiment of no greater 

 dietetic value than tea or coffee. 



ACCESSORY FOOD FACTORS 



Little need be added to what has already been said regarding this 

 subject. The practical point to be remembered is that there are at least 

 two accessory factors concerned, one of them soluble in fat and present 

 in adequate amount in butter and other animal fats but not in vegetable 

 oils, and the other soluble in water and present in wheat, vegetables, 

 fruits, etc. Milk contains both of these factors, so that its inclusion in 

 a diet is a safeguard not only against inadequacy in suitable protein, but 

 also against the absence of accessory food factors. There is little danger 

 of the diet being inadequate with regard to food factors if it contains 

 some fruits or green vegetables or unheated fresh milk. The food fac- 

 tors are destroyed by prolonged cooking. 



DIGESTIBILITY AND PALATABILITY 



We have seen that practical dietetics depends on several factors, the 

 exact relative importance of which can not perhaps be gauged in every 

 case, but preparation of the food so as to make it appetizing must un- 

 doubtedly rank high. The importance of good cooking will now be ap- 

 parent. It is the act of making food appetizing and therefore digestible. 

 It is really the first stage in digestion, the stage that we can control, and 

 one therefore to which much attention must be given, especially when it 

 becomes necessary to make attractive articles of diet ordinarily considered 

 common and cheap. Most people can cook a lamb chop so as to make it 



