Supplementation of infant formula with the probiotic Lactobacillus reuteri and zinc: Impact on enteric infection and nutrition in infant rhesus monkeys

Gut colonization by Lactobacillus reuteri may have beneficial effects on infant health or capacity to resist infectious disease. Zinc supplementation has also been proposed to increase infants' resistance to disease; however, many studies have yielded conflicting results. Objectives: To study effects of probiotic supplementation of infant formula (with or without supplemental zinc) on nutritional status, gut colonization and the ability to resist gastrointestinal infection in an infant rhesus monkey model. Methods: Infant monkeys were fed control infant formula (5 mg Zn/L), control formula with L. reuteri or control formula with L. reuteri and supplemental zinc (15 mg Zn/L) from birth to 4 months. Growth, nutritional status, mineral absorption, intestinal colonization and frequency and severity of enteropathogenic Escherichia coli-induced gastroenteritis were monitored. Results: Gastrointestinal L. reuteri colonization was achieved and was associated with increased ileal villous surface area and improved hematocrit, with no adverse effects on growth or nutritional indices. Fortification to 15 mg Zn/L reduced plasma copper, erythrocyte Cu/Zn-superoxide dismutase, hemoglobin, and iron absorption. Infants fed L. reuteri-supplemented formula had reduced diarrhea severity throughout the study period and recovered more rapidly from acute diarrhea than the other groups. Conclusion: L. reuteri-supplementation of infant formula is safe, improves iron status and decreases diarrhea severity in infant rhesus monkeys and thus may help protect formula-fed human infants from infection and nutritional deficiencies.