Effect of Hydrogenated Fat on Abnormal Carbohydrate Respiratory Quotients of Rats on a Fat-Deficient Diet

Abstract

Conclusion

The partial hydrogenation of the alcohol-soluble fraction of lard, leading to the complete or almost complete destruction of the linoleic acid contained therein, does not diminish the effectiveness of the fat with respect to the lowering of the abnormal respiratory quotients of rats on a fat-deficient diet. Further indication is thereby given that the carbohydrate factor postulated as present in natural fats is not linoleic acid, the lack of which in the diet of rats has been found to produce other deficiency symptoms.

One of us reported 1 that extremely small amounts of fats have an influence on metabolism greatly in excess of their effect as fat per se because of a possible new dietary factor present in the fats. Evans and Burr 2 announced the discovery of a syndrome characterized by subnormal growth and retardation or suppression of ovulation, which developed in rats maintained on a fat-deficient diet. Burr and Burr 3 described additional symptoms of this fat deficiency disease in rats as scaly skin, necrotic tail, and hemorrhagic kidneys, and recognized 4 the fat-contained dietary factor as linoleic acid. A cooperative investigation by one of us (W) with Dr. Burr indicated that while linoleic acid is curative for the abnormalities described by Evans and Burr and Burr, it is not curative for the metabolic abnormality described by Wesson. 5

In the present paper, a comparison is made of the effects of an active natural fat containing linoleic acid on this abnormal metabolism before and after hydrogenation. If hydrogenation does not modify the activity of this fat, a further indication is thereby obtained that linoleic acid is not the active constituent of the fat with respect to carbohydrate metabolism.

The symptom of a deranged metabolism that appears in rats maintained on a diet deficient in fat consists of an abnormal tendency to form fat from carbohydrate, which may be alleviated by small amounts of an active fat. 6 This abnormal tendency to form fat from carbohydrate is detected by means of respiratory quotient determinations obtained during the 6 hours following the feeding of a definite amount of carbohydrate. The normal tendency to form fat from carbohydrate due to over-filling of the glycogen stores is avoided by a preliminary 18–20 hour fast. Reference is made to preceding papers 6 ,⁷ for details of the fat-deficient diet, procedure, and previous findings.