for a growing infant. To extrapolate from the AI for infants ages 0 through 6 months to an AI for infants ages 7 through 12 months, the following formula is used:
For water, potassium, and sodium, data were not available to set the EAR and Recommended Dietary Allowance (RDA) for children ages 1 year and older and for adolescents. In the case of sodium and potassium, the AI was extrapolated down from adults by using the average of median energy intakes for both genders for each age group from NHANES II data (IOM, 2002/2005). Extrapolating on the basis of energy intake was used rather than on the basis of body weight because high levels of physical activity have an effect on losses of electrolytes in sweat.
The formula for the extrapolation is
Because data were not available to set the Tolerable Upper Intake Level (UL) for sodium for children, the UL for adults was extrapolated down using the median energy intakes (kcal/day for each age group) (IOM, 2002/2005):
Energy intake was used as the basis for extrapolation rather than body weight because this method was not used in the nutrients included in the report.
For sodium the AI for older adults is extrapolated from younger adults based on the combined average of median energy intakes for