Because clinical signs of deficiency appear at intakes of less than 0.5 to 0.6 mg/day whereas most studies report normal EGRAC values at intakes of less than 1.3 mg/day, and because there is an expected curvilinear biological increase of values from deficient to minimally adequate, it is estimated that the EAR for riboflavin for men is 1.1 mg/day and for women is 0.9 mg/day.

The RDA for riboflavin is set by assuming a coefficient of variation (CV) of 10 percent (see Chapter 1) because information is not available on the standard deviation of the requirement for riboflavin; the RDA is defined as equal to the EAR plus twice the CV to cover the needs of 97 to 98 percent of the individuals in the group (therefore, for riboflavin the RDA is 120 percent of the EAR).

Few additional studies estimating the riboflavin requirements have been conducted in the elderly. In healthy elderly women aged 70 years or older, doubling the estimated riboflavin intake by means of a supplement containing 1.7 mg of riboflavin doubled the urinary riboflavin excretion in the supplemented group compared to the unsupplemented group, from 4.36 to 9.06 µmol/g (1.64 to 3.41 mg/g) creatinine (Alexander et al., 1984). Initially all the women