The Preterm Gut Microbiota: An Inconspicuous Challenge in Nutritional Neonatal Care

Abstract

The nutritional requirements of preterm infants are unique and challenging to meet in neonatal care, yet crucial for their growth, development and health. Normally, the gut microbiota has distinct metabolic capacities, making their role in metabolism of dietary components indispensable. In preterm infants, variation in microbiota composition is introduced while facing a unique set of environmental conditions. However, the effect of such variation on the microbiota's metabolic capacity and on the preterm infant's growth and development remains unresolved. In this review, we will provide a holistic overview on the development of the preterm gut microbiota and the unique environmental conditions contributing to this, in addition to maturation of the gastrointestinal tract and immune system in preterm infants. The role of prematurity, as well as the role of human milk, in the developmental processes is emphasized. Current research stresses the early life gut microbiota as cornerstone for simultaneous development of the gastrointestinal tract and immune system. Besides that, literature provides clues that prematurity affects growth and development. As such, this review is concluded with our hypothesis that prematurity of the gut microbiota may be an inconspicuous clinical challenge in achieving optimal feeding besides traditional challenges, such as preterm breast milk composition, high nutritional requirements and immaturity of the gastrointestinal tract and immune system. A better understanding of the metabolic capacity of the gut microbiota and its impact on gut and immune maturation in preterm infants could complement current feeding regimens in future neonatal care and thereby facilitate growth, development and health in preterm infants.

Keywords: development; gastrointestinal tract; growth; gut microbiota; health; immune system; preterm; very low birth weight.

Figure 1

Preterm birth influences breast milk composition and affects maturation processes. Breast milk stimulates maturation of the gastrointestinal tract, gut microbiota and immune system, which, together with its dietary components, promotes post-natal growth and organ development. While preterm birth influences breast milk composition and affects maturation processes, it remains unknown to what extent the preterm gut microbiota is involved in breast milk digestion, and how it contributes to post-natal growth and organ development. Icons were retrieved from The Noun Project. All retrieved icons are licensed as public domain or creative commons (CC BY). Icons were designed by: Cristiano Zoucas (Measuring tape), Design Science (Immune System), Gregor Cresnar (Gears), Jannie Henderickx (baby), Julia Amadeo (Gastrointestinal tract), Julie McMurry (breastfeeding), and Maxim Kulikov (Gut microbiota).

Figure 2

The preterm and term situation of the intestine in early life. In the intestine of infants, maturation of the gut microbiota, gastrointestinal tract and immune system occur at the same time. In the preterm situation, the gut microbiota is low in abundance and in diversity due to the unique set of environmental conditions the infant is exposed to. In the term situation, the gut microbiota is higher in abundance and diversity, and more oriented toward breast milk digestion. The gastrointestinal tract is more mature in term infants compared to preterm infants with regard to enzyme production and activity, nutrient absorption and intestinal motility. Lastly, the preterm situation is characterized by a pro-inflammatory state partly due to a discrepancy in cross-talk between the gut microbiota and immune system, while in the term situation there is oral tolerance.