4 DEPARTMENT BULLETIN 975, U. S. DEPT. OF AGRICULTUEE. 



pared with that in turnips shows that lettuce is a better source of 

 iron. By comparing the lines in the different charts in this way, a 

 person can see what the various foods can be depended on to supply. 



Not aways, however, is the body able to utilize equally well the 

 nutritive elements present in different kinds of food. As will be 

 discussed later, care must be used to select foods not only from a 

 quantitative standpoint, but also with reference to digestibility, cost, 

 dietary suitability, and the relative values of the types of protein, 

 fat, carbohydrate, calcium, phosphorus, and iron which they may 

 contain.^ 



FOOD VALUES NOT SHOWN ON THE CHARTS. 



In publishing these charts, which deal with food factors that can 

 be measured by weight, there is no intention of undervaluing those 

 other factors that can not be so measured, namely, the vitamines. 

 Though the quantities of vitamines in different food materials have 

 not yet been determined and the comparative vitamine values can 

 not yet be satisfactorily expressed by lines or figures, general state- 

 ments can be made in many cases and are given in connection with 

 the charts. 



Scientists now recognize at least three vitamines which, until more 

 satisfactory names are agreed upon, may be called A, B, and C. Vita- 

 mine A is believed to be necessary for normal growth and develop- 

 ment. It is sometimes known as fat-soluble A, because it is found 

 associated with fat, and sometimes as the antirachitic vitamine, be- 

 cause when it is absent from the diet rachitis, or rickets, is likely' to 

 occur. It is found in milk, egg yolk, green-leaf vegetables, fats sur- 

 rounding the vital organs of animals, and to a less extent in meat, 

 and perhaps in certain fruits. Vitamine B is also believed to be 

 necessary for general well-being. It is sometimes called water-solu- 

 ble B, and sometimes the antineuritic vitamine, because lack of it 

 may bring on ]3olyneuritis, or beriberi. It is present in nearly all 

 food materials except those that have been artifically purified, such as 

 white sugar, white flour, and cornstarch, and most table oils. Vita- 

 mine C is sometimes known as water-soluble C, or as the antiscorbutic 

 vitamine, because lack of it may be a cause of scurvy, or scorbute. 

 It is found especially in certain fruits and vegetables, among them 

 tomatoes, carrots, oranges, lemons, and grapefruit. It also occurs 

 in fresh milk and probably in meat. Its efficacy in some foods seems 

 to be easily destroyed by heat and sometimes by drying or even by 

 ordinary storage, so that raw, fresh foods are in general the more 

 reliable sources of it. 



^ The charts are based on average analyses published in Chemistiy of Food and Nutri- 

 tion, by H. C. Sherman, New Yorfe, 1918, and on additional data determined by Lucy H. 

 Giliett at Columbia University. 



