FATS AS ESSENTIAL DIETARY COMl'OXEXTS 879 



presumably, was inactive, inasmuch as it did not contribute to the utiliz- 

 able calories in the diet. In addition to digestibility, several other fac- 

 tors are important in relation to the sparing action of fat on thiamine. 

 Unsaturation of the fat per se apparently does not play a role, except when 

 a complete saturation of the fat is associated with such a high melting 

 point as to render the fat unabsorbable, as was the case with hydrogenated 

 perilla oil. Thus Evans and Lepkovsky^^^ found that fats having an iodine 

 number of only 8 spared thiamine as effectively as did an unsaturated oil 

 with an iodine number of 187. Furthermore, saturated triglycerides such 

 as tricapryhn and trimyristin were found to be very effective in sparing 

 vitamin Bi, although Evans and Lepkovsky^" found that tristearin was 

 inactive. We would expect this to be the case, since it is now known that 

 this triglyceride is practically unabsorbed by the rat.^^°'^^* 



Salmon and Goodman ^^^ demonstrated that the thiamine-sparing action 

 of the synthetic esters varied according to the chain length of the fatty 

 acids. The maximum vitamin-sparing action was found in the case of the 

 Cs-fatty acid ester. The most obvious manner in which fat spares vita- 

 min Bi is by decreasing the oxidation of carbohydrate, whereby the pro- 

 duction of pyruvic acid is markedly reduced. 



Another method whereb}' fat may serve as a sparing agent for thiamine 

 is by influencing the bacterial synthesis of thiamine in the gastrointestinal 

 tract, ^^^lipple and Church ^^^ demonstrated that the feces of rats con- 

 tained some thiamine if lard was incorporated in the diet, even though a 

 thiamine-deficient diet was fed. However, when the lard was omitted 

 from the ration, the thiamine content of the stools dropped to 0. It has 

 also been shown that, in the case of human subjects, the ingestion of car- 

 bohj^drate decreases the excretion of thiamine in the urine. This would 

 seem to indicate that the utilization of thiamine is greater under these 

 conditions. A high-fat diet reduces the thiamine requirement in experi- 

 mental animals,^' ^^^'^^2 but the actual amount of thiamine ingested by 

 human subjects under various dietary conditions is directly correlated 

 with the urinary excretion of vitamin Bi, regardless of the caloric intake. ^^^ 

 All the vitamin ingested is apparently absorbed from the gastrointestinal 



1" H. M. Evans and S. Lepkovskv, J. Biol. Chem., 96, 179-188 (1932). 

 "« R. Hoagland and G. G. Snider, /. Nutrition, 26, 219-225 (194.3). 

 »" W. D. Salmon and J. G. Goodman, J. Nutrition, 13, 477-500 (1937). 

 '80 D. V. Whipple and C. F. Church, J. Biol. Chem., 109, xcviii-xcix (1935). 

 '" A. Arnold and C. A. Elvehjem, Aw. J. Physiol, 126, 289-298 (1939). 

 i»2 F. E. Stirn, A. Arnold, and C. A. Elvehjem, /. Nutrition, 17, 485-495 (1939). 

 1" K. O'She^i Elsom, J. G. Reinhold, J. T. Nicholson, and C. Chernock, Am. J. Med. 

 -Sa., £05, 569-577 (1942). 



