Safety and tolerability following consumption of bifidobacterium longum subspecies infantis in exclusively breastfed term infants

Jennifer Smilowitz, Foods for Health Institute and Dept. of Food Science and Technology,
University of California, Davis, USA

Jennifer T. Smilowitz1,2, Melissa A. Breck1,2, Jackeyln Moya1, Annette Fineberg MD3,
Kathleen Angkustsiri4,5, Mark Underwood MD5
1. Department of Food Science and Technology, University of California, Davis;
2. Foods for Health Institute, University of California, Davis;
3. Sutter Health, Sutter Davis Hospital, Davis, CA;
4. UC Davis MIND Institute, University of California, Sacramento, CA;
5. Department of Neonatology, UC Davis Children’s Hospital, Sacramento, CA

For the first six months of life, Bifidobacterium longum subspecies infantis (B. infantis) is the dominant strain of intestinal bacteria in breast-fed infants delivered vaginally. However, in developed nations, infants delivered by either cesarean section or vaginally have lower levels of intestinal B. infantis than infants born in developing nations. B. infantis has been well-tolerated when provided as a supplement to premature infants, but such data has not yet been reported. One objective of the ongoing Infant Microbiota and Probiotic Intake (IMPRINT) Study was to determine if daily consumption of B. infantis by exclusively breastfed infants for 21 days would be safe and well-tolerated. Before Day 6 postnatal, women and their infants delivered either vaginally or by section-section, were randomized into a lactation support (LS) group or lactation support plus B. infantis (BiLS) group. For women who delivered by cesarean section, the two groups were matched for the time when membranes ruptured before birth (≤ 6 hr or > 6 hr). Starting with Day 7 postnatal, and for 21 consecutive days thereafter, infants in the BiLS group were given daily doses of 1×10^10 CFU of B. infantis (sealed individual sachets provided by Evolve Biosystems Inc., Davis, CA) mixed into 5 mL of their mother’s breastmilk. Mothers collected their infants’ feces and filled out daily questionnaires about infant feeding and gastro-intestinal events. Safety and tolerability was determined from daily logs that prompted parents to assess their infants’ feeding, stooling frequency, consistency, gut symptoms and health outcomes. Birthweight and birth length were self-reported and infants were also weighed by study personnel 1 and 2 months postnatal. Compliance was determined by counting B. infantis sachets used bi-weekly. Compared with the LS group, there were more multiparous women enrolled in the BiLS group (P <0.05). There were no differences between groups for infant gestational age at birth, weight, or breastmilk intake. There was a significant time effect (P < 0.01), time* intervention interaction (P < 0.0005) and intervention effect (P<0.0005) for the daily number of infant stools. The number of infant stools significantly increased from baseline (P< 0.0005) for infants in the LS group and decreased from baseline (P < 0.05) for infants in the BiLS group and significantly decreased during the Post-intervention period for both groups (P<0.0005). The change in stool consistency from baseline to the end of the intervention period was significantly different between groups. The mean percent of watery stools decreased and the percent of soft stools increased by 36% from Baseline to the end of the intervention period for infants randomized into the BiLS group compared with 7% for infants in the LS group (P< 0.05). Parity was unrelated to the number of infant stools or the change in infant stool consistency. The number of adverse events reported were not different between the LS and BiLS groups and the events reported were considered normal for healthy infants. There was no difference in the number of adverse events reported between the LS and BiLS groups, including blood in infant stool or infant body temperature, and parental ratings of GI-related infant outcomes such as general irritability, upset feelings in response to spit-ups, discomfort in passing stool or gas, and frequency of flatulence. Furthermore, there were no differences in the use of antibiotics, gas-relieving medications, or parental report of infant colic, jaundice, number of illnesses, sick doctor visits and medical diagnoses of eczema. B. infantis was determined to be well-tolerated and did not result in any adverse events in normal in healthy term infants.

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