INOSITOL 



anomalous behaviour, although not perhaps to the same extent as 

 choline (page 582). As already pointed out (page 564), it exists in 

 foodstuffs in far larger amounts than do other members of the vitamin 

 B complex, and cases of inositol deficiency in man have never been 

 recorded. 



R. J. Williams ^ has estimated that humans require about 1 g. of 

 inositol per day per 2500 cals. of diet compared with only about 1 mg. 

 per day of aneurine or riboflavine. 



Reference to Section 9 

 I. R. J. Williams, /. Amer, Med, Assoc, 1942, 119, i. 



10. METABOLISM OF INOSITOL 



The inositol concentration of normal human blood plasma ranged 

 from 0-37 to 076 mg. per 100 ml. The daily ingestion of 1-5 g. of 

 inositol generally produced a moderate rise.^ 



Under normal conditions, human subjects excreted 0-626 mg. of 

 inositol per hour in the urine and 0-027 mg. per hour in the sweat. ^ 

 The average inositol content of human sweat was 21 /xg. per 100 ml. 

 and the value did not increase significantly after administration of 

 50 mg. of inositol per day. In a hot, moist atmosphere, the average 

 amount of inositol excreted in the sweat during eight-hourly periods 

 was 0-118 mg. per hour. The corresponding amount excreted in the 

 urine during twenty-four hours was 0-494 mg. per hour. 



When a solution containing 250 mg. of inositol was given orally to 

 rats, about twenty-four hours were required for complete absorption. 

 No increase in the liver glycogen occurred, although less than i % of 

 the dose was excreted in the urine. Fasting did not affect the inositol 

 content of the blood, liver, testis and heart of rats, and the oral ad- 

 ministration of inositol to fasted animals did not increase the amount 

 present in any of the tissues except the heart. ^ At least 7 % of 

 inositol ingested by rats was converted into glucose.^ 



Rat tiss jes contained amounts of inositol ranging from 21 mg. per 

 100 g. in the muscle to 123 mg. per 100 g. in the kidney ; of these 

 amounts, 13 and 88 mg. per 100 g. were present in the free state. ^ 

 These amounts remained virtually imchanged after administration of 

 inositol, confirming earlier observations ® that the rat can synthesise 

 inositol. 



References to Section 10 



1. S. Sonne and H. Sobotka, Arch. Biochem., 1947, 14, 93. 



2. B. C. Johnson. H. H. Mitchell and T. S. Hamilton, /. Biol. Chem., 



1945. 161, 357- 



57^ 



