The purpose of this study is to see whether dietary supplements can change the germs in the intestines of premature infants to be more like those of healthy breast fed term babies.

To determine the optimum dose and optimum dietary supplement to promote a fecal microflora in the formula fed premature infant that is similar to that of the term breast fed infant (a predominance of bifidobacteria). In the initial phase of this trial, 30 premature infants will be randomly assigned to receive increasing doses of one of four dietary supplements: Permeate (a pasteurized human milk concentrate containing human milk oligosaccharides processed by Prolacta), GOS (galacto-oligosaccharides manufactured by Friesland foods), Bifidobacterium infantis or Bifidobacterium animalis. Weekly stool specimens will be examined by PCR to determine content of bifidobacteria and total bacteria. This study is limited to formula fed infants in order to avoid the confounding effects of the human milk oligosaccharides in breast milk. An additional 12 human milk fed infants will be enrolled and will have their diet supplemented with ProlactPlus (a pasteurized human milk concentrate containing humna milk oligosaccharides) or powdered human milk fortifier for comparison

Inclusion Criteria:

• Born in or transferred to UCDMC within the first two weeks of life. Birth weight less than 1500 grams. Gestational age less than 33 completed weeks. Exclusively formula fed.

Exclusion Criteria:

• Gastrointestinal or cardiac anomalies.