004 XIV. NTTTRTTTONAL VALINE OF FATS 



b. Resume of the Effect of Composition on the Nutritional Value of 

 Fats and Oils. There are wide \ariationi5 in tlie proportion of I'.FA, 

 tocopherol, A'itamin A and carotene, and vitamin D, in the v'arions animal 

 and vegetable fats and oils. Since all of these factors are important from 

 a nutritional standpoint, it is evident that variations in the proportion of 

 these several nutrients will result in variations in the nutritional value of 

 the several fats considered. 



No sinp:le fat is high in all of these nutritional components. However, 

 the vegetable fats and oils in general excel in having a high proportion of 

 essential fatty acids, as well as a high content of the tocopherols. On 

 the other hand, animal fats usually have an extremely low EFA content, 

 and the proportion of tocopherol is usually so small that these animal 

 fats become rancid much more readily than do the vegetable fats. Al- 

 though vitamin A per se is found under normal conditions in animal fats, 

 its distribution is quite hmited in these fats. The provitamin A, on the 

 other hand, does occur in a number of vegetable fats, as well as in such 

 animal fats as butter and egg yolk. The vitamins D have an extremely 

 limited distribution but, when they do occur, they are normally found 

 exclusively in animal fats. However, since certain types of vitamins D 

 can be produced by direct irradiation of the foods, vitamin D is found in a 

 number of non-animal fat foods. Its presence in these irradiated foods 

 does not, therefore, imply the presence of animal fat. Even in animal 

 fats the distribution of vitamin D is extremely limited, and one must 

 rely upon other sources when the requirement for vitamin D is high. The 

 beneficial features in the composition of vegetable fats are to a considerable 

 extent retained in the fats after hydrogenation. Thus, hydrogenation 

 does not destroy any large proportion of tocopherol, and considerable 

 amounts of essential fatty acids are still retained in margarines and in 

 most hydrogenated fats. Fatty foods such as margarines are further im- 

 proved by the addition of vitamin A alone or with carotene and vitamin D, 

 so that they contain all of the nutritional adjuncts ordinarily dissolved in 

 fat. 



(2) Comparison of the Nutritional Value of Fats and Oils, Based upon 

 Physiologic Response 



a. Introduction. In addition to the presence of the above-mentioned 

 compounds in fats and oils, further factors which affect the nutritional 

 values are associated with the ability of the animal to utilize these fats. 

 Information including the digestibility of the fats, and the rate of absorp- 



