ANIMAL AND HUMAN REQUIREMENTS 



Human Requirements 



There is general agreement that the minimum intake requisite to 

 maintain normal health lies between 0-5 and 3 mg. per day, although 

 admittedly this is a somewhat wide range. Sebrell et al.} as a result 

 of excretion studies, suggested that a minimum intake of 3 mg. per 

 day was necessary, whilst Williams et al.^ maintained a subject for 

 288 days on a diet that provided 0-35 mg. of ribofiavine per 1000 

 cals., that is, about i mg. per day, and found that, although the per- 

 centage excretion of a 2-g. test dose fell progressively, no clinical 

 symptoms developed. They suggested that the minimum daily 

 requirement was 0-5 mg. per 1000 cals., or about 1-25 mg. per day. 

 Brewer et al.^ calculated the requirement of women to be 1-3 to 1-5 

 mg. per day on a diet supplying 2100 to 2300 cals. per day, whilst 

 Horwitt et al.,^^ from excretion studies over a prolonged period, sug- 

 gested that the daily requirement of an adult was between i-i and 

 1-6 mg. 



Macrae et al.,^ using biological and microbiological methods of 

 assay, which incidentally gave results in excellent agreement with 

 one another, estimated the ribofiavine contents of meals served in 

 Royal Air Force messes, and found that on the average these yielded 

 2 mg. of ribofiavine per day. As there were no signs of ribofiavine 

 deficiency on these diets, they concluded that an intake of 2 mg. per 

 day was in excess of the minimmn requirement. Oldham et al.^ and 

 Hagedorn et <^/.® stipulated a substantially lower figure for the minimum 

 daily intake. The former observed a steady excretion with an intake 

 of 0-5 mg. per day, whilst the latter failed to find any physical signs of 

 ribofiavine deficiency in an adult male maintained for five years on a 

 diet also supplying 0-5 mg. daily. Perhaps these lower values should 

 be accepted with reserve until more is known about the possibility of 

 intestinal synthesis supplying appreciable amounts of ribofiavine. 



The minimum ribofiavine requirement of infants is 0-4 mg. per 

 day ; this maintained the mrinary excretion above a " safe " level of 

 50 fig. per day and the sermn concentration above a minimum of 0-5 

 /xg. per 100 ml., and prevented symptoms of ribofiavine deficiency.^** 

 The most satisfactory criterion of nutritional status uith respect to 

 ribofia\dne is said to be the amoimt in the red blood cells, which should 

 not be less than 2-5 fig. per 100 cells. 



There has been a recent tendency to reduce the official figures for 

 the ribofiavine requirements of man and, whereas the U.S. National 

 Research Council's estimate in 1941 was 3-3 mg. per day for a very 

 active man, 2-2 mg. for a sedentary man, 27 mg. for a very active 

 woman, and 1-8 mg. for a sedentary woman, in 1945 these values 

 were reduced to 2 -6, i -6, 2 -o and i -5 mg. per day respectively. Rations 



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