FATS AS ESSENTIAL DIETARY COMPONENTS 887 



Nightingale et al?"^^ observed an avitaminosis K in rats when dihydroxy- 

 stearic acid triglyceride was incorporated in the diet to the extent of 25%. 

 It is possible that this hydroxy acid may interfere with the synthesis of 

 vitamin K in the intestine. 



There is no explanation as yet for the observation by Booth, Henry, 

 and Kon,23o ^^^^ f^ts exert an antirachitic effect when they are fed to 

 rats receiving high-calcium, low-phosphorus, rachitogenic diets. Thus it 

 was found that vegetable fats devoid of vitamin D and of triglycerides re- 

 synthesized from fatty acids of butter and peanut oil exerted an antirachitic 

 effect differing from that of vitamin D. It is possible that the differential 

 effect of several fats on calcium excretion via the intestine, as demonstrated 

 by Cheng and her co-workers, ^^^ and by Givens^^'' might offer an explana- 

 tion for this phenomenon. 



{12) Fatty Acids as Required Growth Factors for Bacteria 



a. Oleic Acid as a Substitute for Biotin. Although oleic acid can be 

 readily synthesized by the higher animals and cannot be considered as an 

 essential fatty acid, it fails to be synthesized by certain bacteria in the 

 absence of the B vitamin, biotin. Hence, in the absence of biotin, oleic 

 acid can serve as a stimulant to growth for a number of bacteria. Cohen 

 et al}^^ were the first to report that oleic acid is required by bacteria. They 

 stated that oleic acid was essential for the growth of Corynehacterium di- 

 phtheriae. Subsequently it was also found to be essential for Clostridium 

 tetani, Clostridium perfringens, and for certain other bacteria. Kodicek 

 and Worden^^^ noted that oleic, linoleic, and linolenic acids inhibited the 

 growth and lactic acid production of Lactobacillus helveticus. Williams, 

 Broquist, and SnelP^^ reported that several cultures of lactic acid bacteria 

 require oleic acid, linoleic acid, or a combined source of these materials 

 to effect growth. The even-numbered saturated acids from C2 to C18 

 were found to be completely inactive. In the case of Lactobacillus bul- 

 garicus, oleic acid, although essential for growth, is so toxic that its growth- 

 promoting action can be observed only within a narrow range of concentra- 

 tions and pH. The addition of detergents such as Tween 40, which are 

 inactive by themselves, renders oleic acid non-toxic, and extends the pH 

 range over which activity can be observed. Tween 80, a water-soluble 

 ester of oleic acid, is an excellent non-toxic source of oleic acid for use in 



229 G. Nightingale, E. E. Lockhart, and R. S. Harris, Arch. Blochem., 12, 381-387 

 (1947). 



230 R. G. Booth, K. M. Henrv, and S. K. Kon, Biochem. J., 36, 445-455 (1042). 



231 S. Cohen, J. C. Snyder, and J. H. Mueller, /. BaderioL, 4I, 581-590 (1941). 



