of this evidence to human health effects in vivo is highly questionable. Nevertheless, it is theoretically plausible that riboflavin increases photosensitivity to ultraviolet irradiation. Additionally, there is a theoretical risk that excess riboflavin will increase the photosensitized oxidations of cellular compounds, such as amino acids and proteins (McCormick, 1977) in infants treated for hyperbilirubinemia, with possible undesirable consequences.

The data on adverse effects from high riboflavin intake are not sufficient for a quantitative risk assessment, and a UL cannot be derived.

There is some in vitro evidence that riboflavin may interfere with detoxification of chrome VI by reduction to chrome III (Sugiyama et al., 1992). This may be of concern in people who may be exposed to chrome VI, for example, workers in chrome plating. Infants treated for hyperbilirubinemia may also be sensitive to excess riboflavin, as previously mentioned.

Although no UL can be set for riboflavin, an intake assessment is provided here for possible future use. Data from the Third National Health and Nutrition Examination Survey (see Appendix H) showed that the highest mean intake of riboflavin from diet and supplements for any life stage and gender group reported was for males aged 31 through 50 years: 6.9 mg/day. The highest reported intake at the ninety-fifth percentile was 11 mg/day in females over age 70 years.

No adverse effects have been associated with excess intake of riboflavin from food or supplements. This does not mean that there is no potential for adverse effects resulting from high intakes. Because data on the adverse effects of riboflavin intake are limited, caution may be warranted.