Potatoes ix the Dietary 1543 



repair of ilic b(xl>'; on water for its im-portant part in the transportation 

 of the food within the body, for keeping the food in dilute form, and for 

 washing out waste from tissues and intestines. However, the majority 

 of housewives have not reaHzed the importance of another group of food- 

 stuffs, the mineral, or ash, constituents of our food. 



Although their percentage in foods is small, the part the ash constit- 

 uents play in constructing tissue and in keeping the body in good working 

 order is by no means a minor one. Calcium is important in building 

 bones and teeth; phosphorus is essential not only to build tissue but also 

 to stimulate gro\\1:h ; iron is necessar>^ for making red blood cells and other 

 tissues. Vegetables furnish iron in larger proportions than do most 

 animal foods. 



All the fluids of the l>of1\- must be kept slightly alkaline. This is best 

 accomplished by including sufficient base-yielding substances in our foods. 

 Certain of the ash constituents in the food materials are so changed in their 

 course through the body that the final product is an acid; others yield as 

 a final product a base, or alkaH. In most of our food materials both these 

 kinds of ash constituents are included. The quantity of the acid-forming 

 elements as compared with the quantity of the base-forming elements 

 therefore determines whether a particular food material is acid-forming 

 or base-forming in the system. The acid-forming foods, which are meats, 

 eggs, and cereals, should be balanced in every meal by those that are base- 

 forming, namely, fruits, vegetables, legumes, and milk, in order that an add 

 condition in the system may not result. An excess of bases in the daily 

 dietary is probably more favorable to health conditions than an excess 

 of acids. This explains why a meal of meat and cereal, while being fairly 

 well balanced as to starch and protein, needs the addition of a fruit or a 

 vegetable. In vegetables lies our chief dependence for salts of potassiimi 

 and magnesium, two of the important base-forming elements. 



SPECIFIC functions AS SERVED BY THE POTATO 



Consiihicnts 



Turning now to the potato it is found that a very high proportion, from 

 75 to 79 per cent, is water; from 18 to 20 per cent is carbohydrate, chiefly 

 starch; from 2 to 2.5 per cent is protein; about i per cent, a relatively 

 large amount, is ash; and an inconsiderable proportion is fat. 



From this it is seen that the potato is rightly called a starchy food. Its 

 value is not dependent on its high starch content alone, however, for it 

 supplies also bulk,- another requirement in the diet. Further, in the 

 mineral content are found moderate amounts of the necessary compounds 



^ By bulk is meant that part of a food which is not digested and absorbed and which therefore is 

 of service in hastening waste products along the intestinal tract. 



