Fatty Acids Synthesized by the Action of Thiamine*

Fat which has been synthesized by rats from carbohydrates is characterized by the presence of large amounts of Cl6 fatty acids (1). In such synthetic depot fat, the total (716 acids constitute 40 to 45 per cent of the total mixed acids. The value for the Cl6 acids is approximately 25 per cent when fat is present in the animal’s diet and is being deposited directly. A particularly striking increase is noticed in the proportion of palmitoleic (Agslo-hexadecenoic) acid in the synthetic fat. On a molar basis, the values for this component are usually about 15 per cent in the synthetic fat, compared with 3 to 4 per cent when the animal is ingesting fat rather than synthesizing its depot fat entirely from non-lipid sources. The production of fat from carbohydrate in the presence of thiamine was demonstrated by McHenry (2) who showed a marked increase in liver fat in young rats when the vitamin was added to a basal diet low in choline and fat-free. Subsequent studies (3) showed that thiamine, as a supplement to basal rations which were deficient in vitamin B1, caused an increase in the amount of total fatty acids in both rats and pigeons. These results strongly supported the hypothesis advanced by McHenry (4) that “vitamin B, is necessary for the synthesis of fat from carbohydrate.” The present test of the above hypothesis of thiamine action was