母乳的益處

母乳為寶寶的成長和發育所必需的所有營養成分, 包括各種宏量營養素(脂肪、碳水化合物和蛋白質)、微量營養素(維生素和礦物質)以及發育因子(長鏈多不飽和脂肪酸即LCPUFA、生長因子和細胞因子)。母乳還具有保護作用,可通過免疫球蛋白和抗感染蛋白質等減少感染。因此,建議在寶寶出生頭六個月以純母乳餵養,之後再添加輔食的基礎上母乳餵養至少一年。

宏量營養素

脂肪
母乳脂肪佔足月產嬰兒熱量攝入量的 50%-60%。此外,脂肪在為寶寶提供游離脂肪酸和脂溶性維生素方面還起到重要作用。甘油三脂由不飽和脂肪酸與飽和脂肪酸組成,是母乳中含量最多的脂肪類,佔總脂肪量的 98% 以上。二十二碳六烯酸 (DHA) 、花生四烯酸 (AA) 等 LCPUFA 尤為重要,因為這些物質積聚在大腦和視網膜的膜脂中,保證重要的視覺和神經功能。確實,寶寶的母乳攝入量越高,大腦皮層、灰質和白質中的DHA 和AA 血漿濃度水平就越高,而且寶寶到15 歲時的智商也會高於用不含LCPUFA 嬰幼兒配方奶粉餵養的寶寶。

碳水化合物

乳糖是母乳中的主要碳水化合物,為寶寶提供 30%-40% 的能量。乳糖是寶寶的主要能量來源,已被分解為葡萄糖和半乳糖。葡萄糖大多數被傳入外周環流,作為產生能量的基質,但是肝臟吸收了半乳糖並將半乳糖轉化為葡萄糖-1-磷酸鹽,半乳糖逐漸被轉化為葡萄糖或用於補充肝肌糖元貯備。大腦還可以利用半乳糖和葡萄糖產生能量,半乳糖對半乳醣脂(腦苷脂)的產生尤為重要,對寶寶中樞神經系統的發育必不可少。
 
母乳低聚醣 (HMO) 低聚醣是由三到十種單醣組成的複合碳水化合物。 HMO 是母乳中的第三大營養成分,次於乳糖和三酰基甘油。因為小腸不消化吸收 HMO,所以 HMO 並不是寶寶的主要能量來源。但是,HMO 具有重要的免疫功能,起到益生元的作用,促進共生菌的腸道生長,尤其 Bifidobacterium longum subsp infantis 和 B.bifidum。同時還起到目標或受體類似物的作用,可抑制輪狀病毒等病原菌粘附在腸道表面。 HMO 還可以保護胃腸道,防止壞死性小腸結腸炎,對於早產兒(胎齡小於 36 週)可能尤為重要,因為他們更容易患 NEC。

蛋白質

蛋白質為寶寶提供大約 8% 的能量。母乳中的蛋白質超過 415,大部分是活性的,具有保護寶寶的功能。雖然不同媽媽的蛋白質水平差別很大,但是初乳中的蛋白質水平較高 (30-70g/l),而成熟乳的蛋白質水平較穩定,僅有 7-14g/l。母乳中的蛋白質可分為三種: 酪蛋白、乳清蛋白和與乳脂肪球膜相關的蛋白質。初乳中的乳清蛋白佔總蛋白含量的絕大多數,而成熟奶中的乳清蛋白降至 60% 左右。
 
β-酪蛋白等蛋白質具有重要的抗菌和抗感染功能,可抑制細菌和病毒。此外,α-乳白蛋白的消化吸收所產生的縮氨酸對革蘭氏陽性和革蘭氏陰性菌具有很強的抑菌活性。母乳中的其它蛋白質(sIgA、乳鐵蛋白和溶菌酶、巨噬細胞、游離脂肪酸等)也都能夠發揮抗感染劑的作用,是早產兒所必需的。這些抗感染劑共同協同作用,抑制、殺死或結合某些微生物,防止微生物粘附在粘膜表面。
 
同時,母乳中含有的保護性共生菌成為腸道菌群的一部分,影響炎性和免疫調節過程。共生菌不僅抑制病原菌的過度生長,還降低腸道pH值、發酵乳糖、分解脂質和蛋白質並產生維生素 K 和維生素 H。

微量營養素

母乳為寶寶提供脂溶性維生素、水溶性維生素、礦物質和微量礦物質等微量營養素,這些營養素都取決於媽媽的飲食。鈣和磷酸鹽雖然與產婦飲食攝入量無關,但卻是酪蛋白膠粒的主要成分,是骨礦化所需要的。母乳中的微量元素包括銅、鋅、鋇、鎘、銫、鈷、鈰、鑭、錳、鉬、鎳、鉛、銣、錫和鍶,僅在母乳中才具有高生物有效性。

細胞

母乳含有母體活細胞,包括血液白細胞、乳腺上皮細胞和紅細胞碎片。白血球既保護媽媽又對寶寶有免疫保護作用。母乳中還有乾細胞,在體外乳腺分化條件下可分化為乳腺上皮細胞譜系,以及微環境中的其它細胞,包括骨細胞、腦細胞、肝細胞、胰島 β 細胞和心肌細胞。幹細胞對寶寶的作用仍未確定,需要進一步研究才能了解其作用。
 
人造乳製品不可代替母乳成分,尤其是母乳幹細胞。純母乳餵養可滿足足月寶寶頭六個月的營養需求,之後在添加輔食的基礎上繼續母乳餵養兩年。

研究摘要

 

Human milk oligosaccharides and their potential benefits for the breast-fed neonate (英语)

Human milk oligosaccharides (HMO), unconjugated complex carbohydrates that are highly abundant in human milk but not in infant formula, have recently received much attention due ...

Jantscher-Krenn E, Bode L (2012)

Minerva Pediatr. 64(1):83-99
Proteome mapping of human skim milk proteins in term and preterm milk(英语)

The abundant proteins in human milk have been well characterized and are known to provide nutritional, protective, and developmental advantages to both term and preterm ...

Molinari CE1, Casadio YS, Hartmann BT, Livk A, Bringans S, Arthur PG, Hartmann PE (2012)J

Proteome Res. 11(3):1696-714

 

參考文獻

Bode, L. Human milk oligosaccharides: every baby needs a sugar mama. Glycobiology 22, 1147-1162 (2012).

Caicedo, R.A. et al. The developing intestinal ecosystem: implications for the neonate. Pediatr.Res. 58, 625-628 (2005).

Claud, E. C. Probiotics and neonatal necrotizing enterocolitis. Anaerobe 17, 180-185 (2011).

Cregan, M.D. et al. Identification of nestin-positive putative mammary stem cells in human breastmilk. Cell Tissue Res 329, 129-136 (2007).

Fleith, M. and Clandinin, M.T. Dietary PUFA for preterm and term infants: review of clinical studies. Crit Rev Food Sci Nutr 45, 205-229 (2005).

Fransson, G.B. and Lonnerdal, B. Zinc, copper, calcium, and magnesium in human milk. J.Pediatr. 101, 504-508 (1982).

Froehlich, J.W. et al. Glycoprotein expression in human milk during lactation. J.Agric.Food Chem. 58, 6440-6448 (26-5-2010).

Garrido, D. et al. Oligosaccharide binding proteins from Bifidobacterium longum subsp. infantis reveal a preference for host glycans. PLoS.One. 6, e17315 (2011).

Gartner, L.M. et al. Breastfeeding and the use of human milk. Pediatrics 115, 496-506 (2005).

Hale, T. W. and Hartmann, P. E. Textbook of Human Lactation 2007a).

Hale, T. W. and Hartmann, P. E. Textbook of human lactation (Hale Publishing LLP, Amarillo TX, 2007b).

Hassiotou, F. et al. Breastmilk is a novel source of stem cells with multilineage differentiation potential. Stem Cells 30, 2164-2174 (2012a).

Hassiotou, F. and Geddes, D. Anatomy of the human mammary gland: Current status of knowledge. Clin Anat(19-9-2012b).

Innis, S.M. Dietary triacylglycerol structure and its role in infant nutrition. Adv.Nutr. 2, 275-283 (2011).

Jantscher-Krenn, E. et al. The human milk oligosaccharide disialyllacto-N-tetraose prevents necrotising enterocolitis in neonatal rats. Gut 61, 1417-1425 (2012).

 

Jensen, Robert G Handbook of milk composition (Academic Press, San Diego, 1995).

Khan, S. et al. Variation in Fat, Lactose, and Protein Composition in Breast Milk over 24 Hours: Associations with Infant Feeding Patterns. J Hum Lact Online ahead of Print, (2012).

Kunz, C. and Lonnerdal, B. Re-evaluation of the whey protein/casein ratio of human milk. Acta Paediatr. 81, 107-112 (1992).

Molinari, C.E. et al. Proteome mapping of human skim milk proteins in term and preterm milk. J Proteome Res 11, 1696-1714 (2-3-2012).

Neu, J. Neonatal necrotizing enterocolitis: an update. Acta Paediatr.Suppl 94, 100-105 (2005).

Neville, M. Physiology of lactation. Clin Perinatol 26, 251-79, v (1999).

Newburg, D.S. and Walker, W.A. Protection of the neonate by the innate immune system of developing gut and of human milk. Pediatr Res 61, 2-8 (2007).

Saarela, T., Kokkonen, J. & Koivisto, M. Macronutrient and energy contents of human milk fractions during the first six months of lactation. Acta Paediatr. 94, 1176-1181 (2005).

Sela, D.A. et al. An infant-associated bacterial commensal utilizes breast milk sialyloligosaccharides. J Biol Chem 286, 11909-11918 (8-4-2011).

Shulman, R.J., Wong, W.W. & Smith, E.O. Influence of changes in lactase activity and small-intestinal mucosal growth on lactose digestion and absorption in preterm infants. Am.J.Clin.Nutr. 81, 472-479 (2005).

Thomas, E. et al. Transient Silencing of 14-3-3sigma promotes proliferation of p63-positive progenitor cells isolated from human breastmilk in mammary epithelial cell culture. unpublished(2010).

Wade, N. Breast milk sugars give infants a protective coat. New York Times (3-8-2010).

WHO and UNICEF. Global strategy for infant and young child feeding (World Health Organization, Geneva, 2003).

Wu, S. et al. Annotation and structural analysis of sialylated human milk oligosaccharides. J Proteome Res 10, 856-868 (4-2-2011).