Table 2.
Concentration levels of free amino acids in breast milk provided to preterm infants with “faster” or “slower” growth during the W2 to W4 lactation period.
| Free Amino Acids (µM) | W2 to W4 Median (25% and 75% Percentile) | Mann-Whitney p-Value from W2 to W4 | FDR Corrected MW q-Value from W2 to W4 | MLR p-Value From W2 to W4 | FDR Corrected MLR q-Value from W2 to W4 | |
|---|---|---|---|---|---|---|
| “Slower” Growth (n = 38) | “Faster” Growth (n = 29) | |||||
| EAA | 234.4 (216.9–278.5) | 277.1 (221.4–343.5) | 0.0675 t | 0.18 | 0.06 # | 0.08 # |
| Arginine | 11.02 (7.56–21.84) | 18.34 (11.45–28.13) | 0.0079 ** | 0.05 * | 0.10 # | 0.08 # |
| Isoleucine | 10.12 (7.56–14.51) | 10.70 (8.12–18.01) | 0.2224 | 0.29 | 0.08 # | 0.44 |
| Leucine | 30.23 (19.93–35.46) | 32.25 (24.00–39.02) | 0.2407 | 0.29 | 0.05 # | 0.40 |
| Proline | 30.21 (26.56–37.13) | 30.32 (26.16–38.80) | 0.9425 | 0.49 | 0.85 | 0.83 |
| Methionine | 5.29 (3.11–8.35) | 6.27 (3.88–8.90) | 0.6038 | 0.43 | 0.44 | 0.74 |
| Phenylalanine | 12.43 (8.81–15.47) | 12.42 (7.25–16.43) | 0.9277 | 0.48 | 0.48 | 0.77 |
| Threonine | 86.71 (74.34–115.7) | 78.62 (66.76–107.5) | 0.3197 | 0.31 | 0.39 | 0.71 |
| Tryptophan | 2.48 (1.89–4.23) | 2.73 (1.97–4.22) | 0.7676 | 0.45 | 0.59 | 0.21 |
| Valine | 51.13 (38.90–55.06) | 52.09 (37.75–56.30) | 0.8034 | 0.45 | 0.41 | 0.71 |
| NEAA | 2610 (2146–3280) | 2512 (1753–3182) | 0.2592 | 0.32 | 0.78 | 0.25 |
| Alanine | 206.7 (186.9–332.4) | 201.0 (166.5–254.3) | 0.5466 | 0.43 | 0.78 | 0.83 |
| Aspartic acid & asparagine | 66.93 (39.53–90.83) | 57.39 (29.92–80.49) | 0.3382 | 0.31 | 0.86 | 0.83 |
| Glutamine | 455.9 (211.4–902.3) | 375.0 (134.4–572.0) | 0.0838 t | 0.17 | 0.14 | 0.52 |
| Glutamic acid | 1319 (898.5–1449) | 1220 (906.3–1480) | 0.6567 | 0.43 | 0.27 | 0.62 |
| Glx | 1838 (1381–2259) | 1754 (1177–2098) | 0.0613 t | 0.14 | 0.52 | 0.21 |
| Glycine | 89.25 (68.99–105.2) | 69.60 (54.38–103.09) | 0.0126 * | 0.05 * | 0.18 | 0.56 |
| Serine | 86.01 (68.78–116.2) | 86.01 (63.81–112.3) | 0.8034 | 0.46 | 0.23 | 0.59 |
| Tyrosine | 11.64 (6.70–15.56) | 14.49 (11.47–21.00) | 0.0349 * | 0.10 | 0.11 | 0.49 |
| Taurine | 313.9 (275.5–428.2) | 270.0 (174.0–313.2) | 0.0031 ** | 0.03 * | 0.14 | 0.51 |
| BCAA | 85.15 (71.48–93.3) | 101.1 (84.99–121.5) | 0.0075 ** | 0.04 * | 0.06 # | 0.08 # |
| Insulino-trophic amino acid | 182.0 (166.6–219.2) | 224.9 (175.7–275.0) | 0.0427 * | 0.10 t | 0.07 # | 0.08 # |
| SAA | 327.9 (297.0–430.7) | 227.9 (168.6–355.1) | 0.0019 ** | 0.03 * | 0.13 | 0.09 # |
Values are medians (25% and 75% percentiles) from amino acid concentrations from week 2 to week 4 of lactation period. EAA: essential amino acids; NEAA: non-essential amino acids; FAA: free amino acid; Glx: glutamine + glutamic acid; BCAA: branched chain amino-acids (valine + leucine + isoleucine); Insulinotrophic and glycemic amino acids = valine + leucine + isoleucine + threonine + arginine. Sulfur amino acids (SAA): taurine and methionine. Variables were considered as significantly modified between the two groups of infants’ growth (Mann-Whitney U test) when their multiple comparisons adjusted P-values (i.e., False Discovery Rate (FDR) corrected-MW q-value) was < 0.05. *: MW p-value or FDR-corrected MW q-value < 0.05; **: MW p-value or FDR-corrected MW q-value < 0.01; t: MW p-value or FDR-corrected MW q-value < 0.1. Multiple linear regression (MLR) for infant weight Z-score (p-value) was also combined to FDR and predictive ability for infant weight growth was considered reliable when MLR q-value was < 0.1 (#).