Table 2.

Amino acid composition of human milk (based on 20 to 24 h amino acid hydrolysis period) collected from women between 3 and 42 weeks post-partum from data published before 2023 (n = 26 studies) and values reported in the systematic review of Zhang et al. (48).¹

	Amino acid composition
Amino acid	mg/L	mg/g DM2	mg/g TP3	Zhang et al. (48) mg/L1
Indispensable amino acid
Histidine	280.8 ± 12.65	2.3 ± 0.11	31.2 ± 1.47	278.0
Isoleucine	572.7 ± 15.68	4.7 ± 0.15	63.6 ± 1.81	597.5
Leucine	1084.4 ± 29.47	9.0 ± 0.26	120.0 ± 3.10	1117.0
Lysine	755.0 ± 23.85	6.2 ± 0.20	83.8 ± 2.73	755.5
Methionine	162.2 ± 6.60	1.3 ± 0.06	18.0 ± 0.71	172.0
Phenylalanine	420.8 ± 16.60	3.5 ± 0.14	46.8 ± 2.00	425.0
Threonine	499.0 ± 14.22	4.1 ± 0.13	55.2 ± 1.48	510.5
Tryptophan4	196.1 ± 11.84	1.5 ± 0.18	21.6 ± 1.30	222.0
Valine	596.7 ± 19.31	4.9 ± 0.19	66.3 ± 2.18	625.0
Dispensable amino acid
Alanine	422.1 ± 16.36	3.5 ± 0.15	46.9 ± 1.72	436.5
Arginine	411.2 ± 19.80	3.4 ± 0.17	45.6 ± 2.14	409.5
Aspartic acid	971.5 ± 26.13	8.0 ± 0.23	107.8 ± 2.88	990.5
Cysteine5	233.2 ± 863	1.8 ± 0.15	26.3 ± 0.98	237.0
Glutamic acid	1898.2 ± 37.87	15.7 ± 0.38	211.1 ± 4.96	1952.5
Glycine	253.8 ± 12.59	2.1 ± 0.11	28.1 ± 1.38	266.0
Proline	937.1 ± 26.35	7.8 ± 0.26	103.9 ± 3.02	976.0
Serine	492.2 ± 14.29	4.1 ± 0.13	54.4 ± 1.23	499.5
Tyrosine	456.6 ± 24.97	3.8 ± 0.21	51.0 ± 2.96	515.0

Values are given as mean ± SEM between studies.

¹Data averaged from milk collected between 3 and 20 weeks postpartum, Zhang et al. (48).

²DM, dry matter; when no dry matter content of breast milk was given in the original publication an average of the collected data (n = 6) was used.

³TP, true protein = N × 6.38 × 0.75.

⁴Tryptophan values from published studies were only included when an alkaline hydrolysis was performed (n = 12).

⁵Cysteine values from published studies were only included when an initial treatment of the sample with performic acid was applied (n = 15).