The urinary excretion curves showed a different
pattern for P and Ca (Fig. 1a and 1b, respectively). A
basal urinary excretion of 0.03 g/d of P was observed,
but starting at 4.96 g/d of STTD P intake, the urinary
P excretion increased linearly (P < 0.001) at a rate of
0.09 g/d per g of STTD P intake. The excretion of Ca
in urine, however, decreased linearly (P < 0.001) at a
rate of 0.08 g/d per g of Ca intake, reaching a basal
urinary Ca excretion of 0.40 g/d at 17.97 g/d of Ca intake.
The daily intakes of STTD P and Ca moderately
R2 = 0.76) at a rate of 1.2%/g of Ca intake, showing a
reduction in the efficiency of Ca absorption.