Figure 1

Growth parameters, serum metabolites and predicted amino acid influx through the blood brain barrier. Association with medical food vs. complete protein intake, history of seizures. (a) A lower weight-for-age (−1.7 ± 2.28 vs. −0.09 ± 1.3; P = 0.038; n = 15 and 8, respectively) and head circumference–for–age Z-score (−2.48 ± 1.43 vs. −1.15 ± 0.88; P = 0.037) and a trend towards a lower mean height-for-age (−1.72 ± 1.01 vs. −0.73 ± 1.37; P = 0.075) and body mass index–for–age Z-score (−0.60 ± 2.08 vs. 0.48 ± 0.99; P = not significant) was observed in the group consuming medical foods compared with patients who did not at the time of evaluation. (b) Patients with a history of seizures had a significantly lower height and OFC Z-scores than those without seizure history (P = 0.004 and <0.001, respectively). (c) Complete protein intake as a percentage of the recommended daily allowance (RDA) correlated positively with height-for-age Z-score (r = 0.575; P = 0.008; R² = 0.31). (d) Patients consuming medical foods had slightly lower total homocysteine concentrations (48.7 ± 27.7 vs. 59.8 ± 25.2; P = not significant), significantly lower plasma methylmalonic acid (2.75 ± 3.27 vs. 13.9 ± 16.4; n = 9 vs. 18; P = 0.012) and methionine concentrations (14.5 ± 6.92 vs. 25.8 ± 8.8; P = 0.004), as expected; and lower valine and isoleucine concentrations (P < 0.001 and 0.026, respectively; data not shown), compared with patients not consuming medical foods. (e) Predicted influx through the blood–brain barrier transporter LAT1 for the propiogenic amino acids and leucine is provided as a Z-score from mean values derived from plasma amino acid concentrations in a control population of 52 children from the Clinic for Special Children. Patients consuming medical foods had mean predicted influx Z-scores lower than those not consuming special formulas (valine: −2.11 ± 0.92 vs. −0.47 ± 0.56; P=0.001; isoleucine: −1.41 ± 1.09 vs. −0.45 ± 0.56; P = 0.045; methionine: −1.29 ± 0.90 vs. −0.61 ± 0.89; P = 0.004; and threonine: −1.33 ± 0.72 vs. 0.06 ± 0.87; P = 0.001). (f) The leucine-to-methionine plasma concentration ratio correlated negatively with the predicted cerebral methionine influx (r = −0.749; R² = 0.541; P < 0.001) as well as the head circumference–for–age Z-scores (r = −0.553; R² = 0.306; P = 0.008 *P<0.05, ** P<0.01, ***P<0.001).