920 XIV. NUTRITIONAL VALUE OF FATS 



(2) Synthetic Fats 



A number of types of synthetic fat were manufactured in Germany dur- 

 ing the war, from petroleum products or from brown coal. The fatty acids 

 and neutral fats obtained were not entirely satisfactory, and posed a num- 

 ber of problems as to palatability and the ability to metabolize the material 

 in a normal manner. For a further discussion of the earlier work the reader 

 is referred to The Lipids, Vol. I, pages 175-178, as well as to the FAO Re- 

 port on Synthetic Fats.^^^ In 1949 Thomas and WeitzeP^^ reported that 

 the use of synthetic fats can be defended on the following grounds: Oxida- 

 tion products are now largely removed with, superheated steam; isoparaf- 

 fins, and iso-fatty acids, can be extracted with solvents; the quantity of 

 diacidogenic fatty acids (Cg-Cn) ingested with the synthetic fats is not 

 sufficient to be harmful, since methylated fatty acids are metabolized to a 

 large extent; succinuria is not necessarily caused by the synthetic fats. 

 These synthetic fats have been greatly improved since the war, and further 

 improvement can be expected. Kraut et al.^^^ reported a number of experi- 

 ments on synthetic fats in which the chain length of the fatty acids was 6 

 to 12 carbons. When synthetic fat was fed to rats they grew less rapidly 

 than did those fed soj'a bean oil, partly because of their repugnance toward 

 the high-fat diet containing the synthetic fat. In the case of dogs, however, 

 there was no growth difference between animals given the synthetic or the 

 natural fat. Moreover, young pigs which had been pair-fed on synthetic 

 and soya fat grew to the same extent. No disturbance in health was ob- 

 served in any case. A fat of a higher iodine number was obtained in the 

 abdominal and back fat of pigs after the feeding of soj^bean oil. However, 

 none of the short-chain acids could be noted in any case following the 

 administration of a synthetic C6-12 fat. The oxyacids present as impurities 

 in the synthetic fats could be identified by taste in the pig fat. This is 

 presumably due to the fact that the oxycarboxylic acids are not completely 

 metabolized, and therefore are deposited in the body fat. It is apparently 

 necessary that all keto- and oxyacids be removed from any su{;h synthetic 

 fat before it can be used for human nutrition. Schaltenbrand and Schorn^^^ 

 observed toxicity Avhen various fats synthesized from coal were fed to rats 

 at levels of 57 or 64% of the total dietary calories. These toxic symptoms 



''* F. A. O. Report, Si/nthetic Fats, Their Polential Contribulion to World Food Require- 

 ments, Washington, D. C., Nov. 3, 1948. 



395 K. Thomas and G. Weitzel, Klin. Wochsehr., 27, 784-78(5 (1949). 



396 H. Kraut, A. Weischer, R. Hugel, and G. Stumpff, Biochem. Z., 318, 472-494 

 (1948). 



39' G. Schaltenbrand and J. Schorn, Deut. Z. Nervenheilk., 159, 408-416 (1948). 



