Untersuchungen über den FettstoffwechseL I.

Abstract

Carefully planned and executed feeding experiments were carried out on human subjects with pure "Undekafat," which contains only one fatty acid. This fatty acid is undecylic acid and has an uneven number of carbon atoms, CH3(CH2)9-COOH. Two subjects were first fed for 4 days with a ketogenic diet containing 300 gm. fat, in the form of butter and lard. After two weeks rest on a normal diet they were fed again for 4 days on the ketogenic diet in which however 100 gm. of undekafat was substituted for 100 gm. of butter. Fat determinations in the stool showed that this fat is absorbed from the bowel as completely as food fat. The excretion of ketone bodies in the urine was considerably less in the 2nd feeding period than in the 1st, which they interpret as definite evidence that the oxidation of undecylic acid in the body does not yield ketone bodies, or at any rate much less than do food fats. There was no difference in the lactic acid content of the urine in both feeding periods. There was greater acidity and more ammonia in the urine in the undekafat period due chiefly to the excretion of undekadiacid, COOH(CH2)9COOH, which was isolated from the urine in considerable quantities (3-4 gm. total). The production of diacid occurs also in the metabolism of even-numbered carbon fatty acids such as are contained in food fats. Accordingly the authors claim that in fat metabolism in addition to B-oxidation [omega]-oxidation goes on in the organism.