XII. REQUIREMENTS AND FACTORS INFLUENCING THEM 399 



a reserve of riboflavin cannot be maintained by men at levels of intake be- 

 low 1.1 mg. per day^^ on a diet containing approximately 2200 cal. Brewer 

 ct al}^ calculated the requirement of women to be 1.3 to 1.5 mg. per day 

 on a diet providing 2100 to 2300 cal. per day. 



The recommended daily allowances of the Food and Nutrition Board 

 of the Xational Research Council state that 1.8 mg. of riboflavin is ade- 

 quate for a 70-kg. adult man, and 1.5 mg. for a 56-kg. adult woman. The 

 assumption was made that increased work and greater than average caloric 

 consumption do not increase the need for riboflavin. The allowances during 

 the latter half of pregnancy and during lactation were increased to 2.5 and 

 3.0 mg., respectively. There is as yet no proof that more than the normal 

 daily allowance is required during pregnancy. This problem was reviewed 

 by Oldham ct al}'^ If one estimates the total amount of riboflavin stored 

 during the gestation period, it seems likely that an additional 0.2 mg. per 

 day should satisfy the needs for growth during pregnancy. The increased 

 allowance for lactation makes ample provision for the amount in human 

 milk, which contains about 0.5 mg. riboflavin per liter. 



The recommended allowances for children are graduated in accordance 

 with the growth rate at different ages. It has been recommended that chil- 

 dren from 1 to 3 years be allowed 0.6 mg. per day, and that children 10 to 

 12 j^ears be allowed 1.8 mg. per day. During the rapid period of growth 

 from 13 to 15 years, it has been recommended that both girls and boys 

 receive 2.0 mg. of riboflavin per day. It is apparent that, since these al- 

 lowances are adjusted for growth requirements, the actual need of an in- 

 dividual ^^^ll vary with his or her own pattern of growth. 



One of the major goals of all the research described in this chapter is to 

 determine how much riboflavin is required by man for optimum nutritional 

 health. The techniques used may be classified under four headings: (1) ob- 

 servations of the repair of pathology by ril)oflavin administration; (2) 

 survey studies of the nutritional status of population groups; (3) experi- 

 mental production of riboflavin deficiency; and (4) evaluation of urinary 

 excretion of riboflavin in health and disease. 



Riboflavin deficiency states ordinarily noted by the clinician, whose pri- 

 mary obligation is to facilitate the repair of apjiarent jiathology, do not 

 often present adequate opportunities to assay the iiulividual's need for 

 riboflavin. The important contributions of these observations arc in the 

 classifications of conditions which can be healed by riboflavin, usually given 



^*M. K. Horwitt, C. C. Harvey. O. W. Hills, and K. Tachort,, ./. Nutrition 41, 247 



(1950). 

 *' W. Brewer, T. Porter, B. Ingalls, and M. .\. Ohlsoii, J. Nutrition 32, HH^i (1946). 

 " H. Oldham, B. B. Sheft, and T. Porter, J. Nutrition 41, 231 (1950). 



