Effects of Feeding an Infant Formula Containing Lactobacillus GG on the Colonization of the Intestine

Objectives: This study aimed to determine whether feeding Lactobacillus GG (LGG) at varying levels (10 8 to 10 10 cfu/day) would result in colonization, defined as ≥1,000 cfu of LGG per gram of stool in 3 of 5 samples collected during the feeding period. Methods: Infants received unsupplemented formula during a 7-day baseline, 1 of 4 formulas containing 0 (control), 10 8 (low), 10 9 (medium), or 10 10 (high) cfu of LGG per day during a 2-week test, and unsupplemented formula during a 2-week follow-up. Baseline, test, and follow-up stool samples were evaluated for levels of viable LGG. Results: During test, supplemented infants were colonized, compared with control (P < 0.05). Median stool counts of LGG (log 10 cfu/g) in colonized infants were 5.24 (low), 6.05 (medium), and 5.97 (high). LGG persisted in the stools for 7 to 14 days after discontinuing LGG. No differences were observed among groups in stool consistency, flatulence, fussiness, or adverse events. Conclusion: A 2-week oral administration of 10 8 to 10 10 cfu/day LGG was well tolerated; all levels successfully colonized the intestinal tract of healthy, term infants.