(P20-014-23) Growth Differences Observed in Meat- vs. Dairy-Based Complementary Feeding Pattern in US Formula-Fed Infants Could Be Mediated by the Gut Microbiota: A Germ-Free Mice Study

Objectives: To determine if gut microbiota drives the growth differences observed in formula-fed infants consuming a meat- vs. dairy-based complementary diet.

Methods: We previously demonstrated that formula-fed infants consuming a meat-based complementary diet had greater linear growth without increasing risk of overweight, compared to formula-fed infants consuming a dairy-based complementary diet from 5 to 12 months of age. Stool samples were collected at 12 months and transplanted into 4-week-old germ-free mice (Meat group male mice n=10, female mice n=15; Dairy group male mice n=13, female mice n=13). Mice consumed a standard chow diet from 4 to 8 weeks. Longitudinal live MRI and CT images were acquired for body composition (adipose and lean muscle tissues) and bone dimensions of the mice at 4 and 8 weeks.

Results: There was no significant difference in body weight (g) or food intake (g/d) between groups or by sex at baseline or over time. Proton-density and Dixion MR images (Bruker 9.4 Tesla MRI)_showed that female mice of the dairy group had greater abdominal fat (11.4±3.4% vs. 9.3±1.7%, P=0.06), total body fat volume (1974±508 vs. 1658±331 mm³, P=0.06) and total brown fat (106±63 vs. 48±36 mm³, P=0.007) than female mice of the meat group at 8 weeks. 3D-CT images (Siemens Inveon microCT) found that female mice from the meat group had greater tibia length gains than female mice from the dairy group (1.62±1.04 vs. 0.95±1.05, P=0.088). Femur or spine length did not differ by groups or over time. Male mice did not show differences in body composition or bone length between groups.

Conclusions: Findings in female gnotobiotic mice were consistent with their microbiota donors in documenting that infants consuming a meat-based complementary diet had greater linear growth while gaining the same weight. Future research needs to investigate the potential sex difference of the growth phenotypes.

Funding Sources: NIDDK 1R03DK120992