Stool Composition and GI Tolerance in Infants Fed a Term Infant Formula with a New Lipid Blend and Lactobacillus reuteri (L.reuteri): A Randomized Controlled Trial

Abstract

Abstract Objectives Differences in dietary fat and calcium absorption between breastfed and formula-fed infants may impact gastrointestinal (GI) tolerance and stooling patterns. We hypothesized that infant formula containing L. reuteri and a new lipid blend with low levels of long-chain saturated fatty acids (LCSFAs) (<13% of triacylglycerols [TAG]) in sn-1,3 positions would result in reduced stool calcium-fatty acid (Ca-FA) soaps and improved stool consistency. Methods Healthy term infants 21–28 days (d) of age were randomized in a double-blind manner to receive intact protein cow's milk-based experimental formula (EF, n = 70) with new lipid blend and L. reuteri at 1 × 10,7 CFU/g or control formula (CF, n = 70) without probiotic and containing a lipid blend with high levels of LCSFAs (∼25% of TAG) in sn-1,3 positions until 3 months (m) of age. A breastfed (BF, n = 75) reference group was also included. Co-primary endpoints were stool consistency (via 3-day diary using validated scale from 1 = watery to 5 = hard) and stool total Ca-FA soaps (expressed as mg/g dry stool weight). Overall GI tolerance was assessed using a validated Infant Gastrointestinal Symptoms Questionnaire (IGSQ) (score range: 13 [no GI distress] - 65 [extreme GI distress]). Results Of 215 enrolled infants, 206 completed the study. Infants fed EF had softer stools vs those fed CF by age 1.5 m (stool consistency score: 2.6 ± 0.1 vs 3.0 ± 0.1, P < .0001) and similar to BF (2.7 ± 0.1, P = .089). This positive effect was sustained until age 3 m (EF vs CF, P = .0006; EF vs BF, P = .373; CF vs BF, P = .014), without increased stool frequency in EF vs CF group throughout the study (1.48 vs 1.50 stools/d, P = .884). Infants fed EF (vs CF) had lower stool total Ca-FA soaps at 3 m of age (60.3 ± 10.1 vs 207.9 ± 10.1, P < .0001), largely explained by stool palmitate soaps which was 7 times lower in EF vs CF (20.7 ± 7.0 vs 142.5 ± 6.9 for CF, P < .0001). Mean IGSQ scores remained very low in EF (≤16.2) and CF (≤15.6) groups over the study period. Incidences of parent-reported GI symptoms and physician-confirmed GI adverse events (including diarrhea) were low and similar for EF and CF groups. Conclusions Infant formula containing L. reuteri and enhanced lipid blend with reduced LCSFAs in sn-1,3 positions reduces stool soaps and promotes softer stools closely resembling the stools of breastfed infants. Funding Sources Sponsored by Nestle Nutrition.