Dietary nucleotides and fecal microbiota in formula-fed infants: a
randomized controlled trial1–3
Atul Singhal, George Macfarlane, Sandra Macfarlane, Julie Lanigan, Kathy Kennedy, Alun Elias-Jones,
Terence Stephenson, Peter Dudek, and Alan Lucas
Background: Dietary nucleotides are nonprotein nitrogenous
compounds that are thought to be important for growth, repair,
and differentiation of the gastrointestinal tract. A higher nucleo-
tide intake may also have favorable effects on the fecal microbial
composition and incidence of diarrhea in infancy. However, few
studies have tested this hypothesis with an experimental study
Objective: We tested the hypothesis that nucleotide supplementa-
tion of infant formula has beneficial effects on fecal bacteriology.
Design: Oligonucleotide probes were used to measure bacterial
genus-specific 16S ribosomal RNA in stools of a subset of infants
(mean age: 20.4 wk) who were randomly assigned to nucleotide-
supplemented (31 mg/L; n ? 35) or control formula (n ? 37) from
microbial pattern was assessed as the ratio of Bacteroides-
Porphyromonas-Prevotella group (BPP) to Bifidobacterium spe-
Results: The ratio of BPP to Bifidobacterium spp. rRNA in infants
randomly assigned to the nucleotide-supplemented formula was
?118%; 95% CI: ?203%, ?34%; P ? 0.007), but it did not differ
in infants who were breastfed. The difference between randomized
formula-fed groups was independent of potential confounding fac-
tors (P ? 0.003).
Conclusions: Our data support the hypothesis that nucleotide sup-
plementation improves the composition of the gut microbiota in
formula-fed infants. Because this effect could contribute to previ-
ously described benefits of nucleotide supplementation for gastro-
intestinal tract and immune function, these findings have important
implications for optimizing the diet of formula-fed infants.
J Clin Nutr 2008;87:1785–92.
Breast milk was shown to have a number of short- and long-
incidence of gastroenteritis in infants breastfed rather than
formula-fed (1, 2). Several factors were suggested to contribute
to this protective effect, including, eg, a higher concentration of
nucleotides in human milk compared with cow-milk-based for-
suggested to be essential nutrients in certain clinical conditions,
to modulate immune function, and to be important for growth,
repair, and differentiation of the gastrointestinal tract (7–12).
However, although nucleotides have been added to some infant
formulas for many years, relatively few data from large-scale
randomized studies support their benefits and use in humans.
In formula-fed infants, dietary nucleotide supplementation
a favorable effect on the gastrointestinal microbiota. For in-
stance, in vitro studies suggest that nucleotides enhance the
growth of bifidobacteria (13–15), which by reducing stool pH
could reduce the growth of pathogenic bacteria and hence the
incidence of infectious diarrhea (7, 8, 10, 16). Bifidobacterium
spp. are found in higher proportions in the stools of breastfed
compared with formula-fed infants (16–19), but whether this
effect is related to the higher concentration of nucleotides in
breast milk compared with formula is uncertain.
Data to support an effect of dietary nucleotides on the gut
addition of nucleotides to infant formula resulted in a microbial
pattern in the stool that was more like that of breastfed infants
(20), whereas, in contrast, another investigation suggested that
dietary nucleotides discouraged the growth of bifidobacteria
(21). However, those previous studies were small and nonran-
domized and used bacterial culture rather than more robust mo-
lecular techniques to assess fecal microbiology (20, 21). Here,
we have investigated the effects of nucleotide supplementation
We used genus-specific 16S ribosomal RNA (rRNA)–targeted,
intake of nucleotides has beneficial effects on the fecal micro-
Group, Ninewells Hospital Medical School, Dundee, United Kingdom (GM
dom (AE-J); the Faculty of Medicine and Health Sciences, Academic Divi-
sion of Child Health, University of Nottingham, United Kingdom (TS); the
HJ Heinz Company Ltd, Kendal, United Kingdom (PD).
2Supported by the Medical Research Council with a charitable contribu-
tion from the HJ Heinz Company Ltd. The trial formulas were generously
Nutrition Research Center, Institute of Child Health, 30 Guilford Street,
London, United Kingdom, WC1N 1EH. E-mail: email@example.com.
Received December 11, 2007.
Accepted for publication February 28, 2008.
Am J Clin Nutr 2008;87:1785–92. Printed in USA. © 2008 American Society for Nutrition
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SINGHAL ET AL
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