Diet and faecal flora in the newborn: nucleotides.

Breast milk contains nucleotide salts that are only present in minimal amounts in modern infant formulas prepared from cows' milk. Nucleotides have been suggested as cofactors for the growth of bifidobacteria in vitro. Bifidobacteria are found to be more numerous in the faeces of breast fed babies compared with those of formula fed babies. Faecal flora were examined at 2 weeks of age in 32 babies who from birth had been fed a whey based formula supplemented with nucleotide monophosphate salts, 33 babies fed an unsupplemented formula, and 21 breast fed babies. Faecal flora were also examined at 4 weeks, and 7 weeks but with fewer babies in each group. Most differences were found at 2 weeks of age when more babies fed the nucleotide supplemented formula were colonised with Escherichia coli and more had E coli as the dominant organism in their faecal flora. Fewer of these babies were colonised with bifidobacteria. The counts of bifidobacteria and enterococci were reduced in the nucleotide supplemented group but bacteroides accounted for a higher percentage of the total flora in this group of babies. Supplementation of a formula with nucleotide salts did not make the faecal flora closer to that of breast fed infants as the growth of bifidobacteria was discouraged. While there may be arguments to support the addition of nucleotides to infant formula the results of this study do not support their addition for the enhancement of bifidobacteria in the faecal flora.