Clxxiii. a Study of the Destruction of Vitamin B1 in Blood

IN a quantitative study of the excretion of vitamin B1 in human urine [Harris & Leong, 1936], it was observed that, with the subjects studied, the daily urinary output of the vitamin amounted to only about 10% of the daily intake. Later, in a more detailed study on rats [Leong, 1937], evidence was obtained that a certain amount of the ingested vitamin could not be accounted for in the total urinary and faecal ex-cretions and that this difference between intake and output could not be ascribed entirely to storage in the tissues. Thus it was clear that some vitamin B1 had disappeared in the body, although the mechanism of (and the factors contributing to) this disappearance remained obscure. This disappearance of the vitamin may be due (among other causes) to (1) conversion into inactive products during metabolism in the tissues and in the blood, and (2) destruction in the alimentary tract, which includes the possible bacterial decomposition of the vitamin in the lower intestine. It was felt that a study of the stability (or the possible destruction) of vitamin B1 in blood at body temperature might yield useful information bearing on these points. The effect of heat on the antineuritic vitamin seems to depend mainly on (1) the pH and (2) the amount of moisture present. Its stability to dry heat has been shown by numerous workers, among whom may be mentioned the following: Holst [1907], Nitzescu [1923], Sherman & Spohn [1923] and Keenan et al. [1935]. The destruction of vitamin B1 when heated under various conditions in contact with moisture has also been widely reported [Grijns, 1901; Sherman & Burton, 1926; Rosedale & Oliveiro, 1928; Elvehjem et al. 1932; Ohdake & Yamagishi, 1935]. No report appears to have been published, however, on the stability of crystalline vitamin B1 at 37°. EXPERIMENTAL