INTESTINAL SYNTHESIS 



What conditions are necessary for intestinal synthesis and why 

 the phenomenon had not previously been discovered in the course of 

 the innumerable experiments that have been carried out is still a 

 mystery, although some of the factors that affect the phenomenon are 

 now known. The authors conclude their paper with these very 

 significant words : " The demonstration that intestinal bacteria can 

 synthesise thiamine carries interesting implications for human nutri- 

 tion. This phenomenon may explain the discrepancies in thiamine 

 requirements found by different observers. Since it is likely that the 

 biosynthesis of thiamine is greatly affected by diet, as is known to be 

 the case in animals, it follows that we must think in terms of require- 

 ments on particular diets rather than of requirements in general." 



In fact, the result appears to call into question the fundamental 

 concept of a vitamin as a substance that must be present in the diet 

 to enable animals to remain healthy. For why, if man can derive 

 his aneurine requirements from his intestinal flora, should vitamin 

 Bi deficiency ever be observed ? The complete answer to this question 

 has not yet been found, but similar observations in respect of other 

 members of the vitamin B complex have been made, with results 

 even more striking than those obtained with aneurine. 



Although their results anticipate much that should properly be 

 reserved for later chapters, it is useful at this stage to refer to the 

 work of Denko et alM These workers measured the faecal and urinary 

 excretions of seven healthy young men maintained on a normal diet 

 containing ^-aminobenzoic acid, biotin, folic acid, pantothenic acid, 

 pyridoxine, aneurine, riboflavine and nicotinic acid, the amount of 

 each of these factors in the diet being measured. The following 

 results were obtained (jug. per day) for the range of the averages of 

 the seven subjects and the mean of the averages : 



Urine Faeces 



^-Aminobenzoic acid 131-198 (148) 183-361 (246) 



Biotin 27-5-35-6 (317) 114-201 (133) 



Folic acid ^-g^-^-gg (3-99) 222-393 (304) 



Pantothenic acid 2-68-3-46 (3-04) 0-89-3-66 (2-20) 



Pyridoxine o-57-o-69 (0-63) 0'33-o-42 (0-38) 



Nicotinic acid i-3i-i-39 (1-21) 2-i4-5-4i (3-63) 



Aneurine 144-323 (227) 109-895 (548) 



Riboflavine 543-913 (678) 823-1313 (1029) 



They indicate that the faecal excretion was higher than the urinary 

 excretion in every instance except pantothenic acid and pyridoxine. 

 A comparison was then made of the ranges and means of the 

 average daily vitamin intakes with the ranges and means of the 

 average urinary and faecal excretions : 



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