Afssa (0000) proposed an Adequate Intake (AI) of 000 mg/day for infants aged 0–00 months, in line with the IOM (0000). For children, Afssa (0000) used a factorial approach to calculate the ARs. Allowing for a phosphorus content of bone (Fomon et al., 0000) and other tissues, values were derived from the amount of calcium required during growth using a calcium to phosphorus ratio of the weight gain of 0:0 up to the age of 00 years, with the amount of phosphorus required for growth ranging from 00 mg/day (age 0–0 years) to 000 mg/day (age 00–00 years). Urinary and faecal losses were estimated in accordance with Wilkinson (0000), Nordin (0000) and Lemann (0000). For absorption efficiency, mean values of 00 % (age 00–00 years) to 00 % (age 0–00 years) were used in children and adolescents (Wilkinson, 0000; Guéguen, 0000). A CV of 00 % was used to derive the PRIs.