An understanding of analytical methods is essential in the appraisal 

 of results. In many instances, two laboratory methods give different 

 results in the hands of a single responsible investigator. Such discrep- 

 ancies may be unexplainable at the time the investigation is reported. 

 Nevertheless, a decision is required as to the use to be made of these 

 data. Although many new and improved techniques for vitamin de- 

 terminations have been developed during the past few years, it is not a 

 safe assumption that the newest is the best method, at least until it 

 has stood the test of time. Yet many of the values coming into the 

 literature may have been obtained in the process of perfecting these 

 techniques. 



Among the problems frequently met is that of a paucity of data for a 

 given nutrient in a food. An attempt was made to draw only upon 

 actual analyses for the values in this table, but had this policy been 

 strictly adhered to many important items in the diet could not have 

 been included. It is not uncommon to find as few as two or three 

 values reported for some of the vitamins in some foods. If these values 

 are not too different, they might be averaged; however, if one is two 

 or three times another, as happens occasionally, an average means little. 

 Sometimes a way out may be found by imputing a value from another 

 form of the same food for which data are more adequate — as dry milk 

 from fluid milk, canned peas from fresh, and so on. Sometimes it 

 seems preferable to impute a value from a similar food, as pumpkin 

 from winter squash. 



The foregoing points have been discussed briefly in order to give the 

 reader some idea of the difficulties encountered and the problems in- 

 volved in preparing a table of food composition. Although it might 

 seem desirable it is not yet possible to reduce the averaging of available 

 data to a completely objective basis. 



Notes on Special Foods or Groups 



"Restored" cereals are not included in this table because at the 

 present time no official standards of restoration have been promulgated 

 and a product may be "restored" in several nutrients or in only one or 

 two. The situation is further confused because different organizations 

 have proposed various levels for restoration. The Food and Nutrition 

 Board of the National Research Council has proposed the following 

 levels: 



Amounts of certain nutrients suggested for cereals 

 restored in thiamine, niacin, and iron 



Thiamine Niacin Iron 



{Mg. per pound) {Mg. per pound) {Mg. per pound) 



Wheat 2.0-3.0 18-36 16-24 



Oats 3.0-4.0 4- 8 14-24 



Rice 1.5-2.5 20-30 10-20 



Corn 1.7-2.6 8-12 6-15 



These limits were selected to comply with what might be considered 

 acceptable whole-grain levels. In deriving them a few exceptionally 

 high values and the inferior grades of the grain were excluded. 



Data on meat include composition of the main grades of carcasses 

 for each kind of meat, the main wholesale cuts, and where possible, in- 



