Studies of the essential unsaturated fatty acids in their relation to the fat-deficiency disease of rats

Abstract

The principal symptoms of the deficiency disease (Burr & Burr) in rats maintained on a complete diet devoid only of fat were reproduced. Resumption of weight increase and healing of skin symptoms were the criteria used to det. the efficacy of various curative materials. A rough method of estimating quantitatively the rate of healing of skin lesions was descr. as an important additional criterion more specific than wt. increase. Methyl linoleate was perhaps 6 times more potent and more lasting in action than methyl linolenate. Mixtures of a and and of y and S-tetra-hydroxystearic acids in daily doses of 0.2 g. were completely ineffective, as was dioxidostearic acid. The hexahydroxy-derivatives, linusic and isolinusic acids, 0.2 g./day, failed to benefit skin lesions but promoted a small but definite wt. increase nearly equal to that evoked by methyl linolenate, 0.08 g./day. All these oxidation products were solids of high m.p. and were certainly absorbed to a very limited extent. The potency of a fraction of the unsat. acids from lard was about the same as that of a similar fraction from linseed oil; raisin seed oil was slightly more potent. The linoleic acid contents of these materials were not greatly dissimilar but linseed oil contained 40% to 50% linolenic acid in addition. The methyl ester of docosahexenoic acid promoted wt. increase but had little or no action in curing skin lesions. Chaulmoogra oil and chaulmoogric acid, methyl arachidate and 9:10:12-trihydroxystearic acid were inactive. The ability of unsaturated fatty acids to supplement a fat-free diet in promoting wt. increase is not necessarily associated with ability to heal skin lesions.