The Effect of Dietary Fat on the Lipotropic Action of Inositol

The possibility that choline exerts lipotropic action through its introduction into newly formed lecithin molecules is an attractive hypothesis for which there exists some supporting evidence (l-3). Inositol, which is also a constituent of phospholipid (4, 5), may possibly exert its effect in the same way. McHenry and Patterson (6) have already suggested this possibility. If these two substances actually do lower liver fat by virtue of their incorporation into phospholipid molecules, then essential fatty acids, which also constitute integral parts of certain phospholipids, might similarly be required before choline and inositol could exert their effects, or benecessary to produce maximal lipotropic action. About the time that experimental work was started to test these points, Engel published a paper (7) in which he mentioned the relation of the essential fatty acids to the lipotropic action of choline. His motives for carrying out this particular investigation differed from those which initiated the present study. Engel had found that pyridoxine is necessary for choline to exert its full lipotropic effect, and because of the complementary relationship of pyridoxine and essential fatty acids in the cure of rat acrodynia (8, 9) he was prompted to examine the possible influence of essential fatty acids on the lipotropic action of choline. Engel fed 0.1 ml. of corn oil to each test rat daily. This supplement did not alter the lipotropic effect of choline in short term experiments (3 weeks), but did augment the latter’s action in an experiment of 8 weeks duration. In a recent publication (10) by one of us, data obtained from a small series of animals supported this finding of Engel’s. Unexpectedly, it was also discovered that corn oil (Mazola brand), which was fed with the object of supplying essential fatty acids, instead of augmenting the lipotropic action of inositol actually obliterated it. The present paper confirms this observation and reports more detailed analytical data for liver fat from rats on a number of diets similar to those utilized in the preliminary work reported by Beveridge (10).