Monash University, Monash Medical Centre, Melbourne, Australia
Objective: To examine the role of dietary nucleotides in healthy and high-risk infants, and the scientific rationale of nucleotide supplementation of formula milk used in infant feeding.
Methods: The immunoprotective benefits of human milk, the biology of human milk nucleotides, and the immunologic and gastrointestinal effects of dietary nucleotides in animal studies and in vitro experiments are examined. Medical evidence for beneficial effects of feeding infants with nucleotide-supplemented formula milk in clinical studies is reviewed, especially its efficacy in enhancing immunity and reducing the risk of sepsis.
Results: Human milk cells and a variety of immunoactive and trophic components of human milk explain the reduced incidence of sepsis in breastfed term and preterm infants in both developing and developed countries. Nucleotides, which are believed to play a immunomodulatory role, are found in lower concentrations in formula milk. Animal studies have documented that dietary nucleotides result in increases in a number of immune responses, and enhance the growth and differentiation of the gut and its recovery from injury. Several clinical studies have reported beneficial effects of nucleotide supplementation on gut microflora, diarrhoea and immune function (five were conducted in term infants and one in preterm infants), and one study reported better catch-up growth in term infants with severe intrauterine growth retardation.
Conclusions: Experience accumulated over a 30-year period suggests that nucleotide-supplemented formula milk is probably safe. Further basic research are encouraged to study the metabolism of nucleotides in neonates. Additional randomised controlled trials are necessary to demonstrate the clinical benefits of nucleotide supplementation, especially in specific high-risk neonatal situations such as extreme prematurity, significant suboptimal nutrient intake before and after birth, and recovery from gut injury.