Dietary Intakes of Formula‐Fed Infants Consuming a Meat‐ or Dairy‐Based Complementary Diet: A Semi‐Controlled Feeding Trial
Authors: Tang Minghua , Griese Kayla E. , Krebs Nancy F. 
Published: November 2023

ObjectiveHigh protein intake from infant formula has been associated with rapid weight gain and increased adiposity, but the effect of type of protein from complementary foods has not been prospectively evaluated. Previous research in adolescents and adults suggest that protein source might play an important role in weight and adiposity regulation. We tested the impact of a complementary diet with protein source from meats or dairy foods in formula‐fed infants.MethodsHealthy, term formula‐fed (breastfed ≤1 month) infants are recruited from metro Denver area. Participants were randomized to a meat‐based complementary diet group (MEAT), or a dairy‐based complementary diet group (DAIRY) from 6 to 12 months of age. Total protein intake (formula + meat or formula + dairy) goal is ~3 g/kg/d, with protein intake from meat or dairy being adjusted monthly based on body weight and formula consumption. Caregivers were provided an individualized diet plan of approximate daily amounts of study foods for the participants to consume. Protein‐based food (meat purees, infant yogurt, cheese, whey protein supplement) and a standard, cow‐milk based formula were provided. Intakes of formula, infant cereal, fruits and vegetables were ad libitum. Three‐day diet records were completed at 5, 10, and 12 months of age.ResultsTo date, 33 infants have completed the trial (17 MEAT, 16 DAIRY). There were no differences between groups for birth weight, gestational age or maternal BMI. At baseline (5 months), protein intake was comparable between the two feeding groups (MEAT: 1.9 ± 0.4 g/kg/d; DAIRY: 2.1 ± 0.4 g/kg/d, P = 0.45). Total protein intake increased during the intervention to 3.2±0.9 g/kg/d and 3.4±1.1 g/kg/d at 10 and 12 months of age, respectively (~15% of energy at both time points), without group difference. Formula provided >80% of total protein intake and meat‐ or dairy‐based complementary foods contributed to less than 5% at baseline. At 10 months, formula provided an average of 28% protein intake and meat‐ or dairy‐based foods provided an average of 65% for both groups. Caloric intake (kcal/kg/d) did not differ over time or between groups at baseline (MEAT: 85 ± 17, DAIRY: 96 ± 16), 10 months (MEAT: 86 ± 22; DAIRY: 90 ± 27), or 12 months (MEAT: 96 ± 25; DAIRY: 100 ± 24). Individual amino acid intakes between the two diet groups were also calculated. Leucine intake was comparable between groups at baseline (MEAT: 1.3 ± 0.3g/d; DAIRY: 1.5 ± 0.3 g/d). At 12 months, MEAT (3.5 ± 1.0 g/d) had a greater leucine intake compared with DAIRY (2.6 ± 0.5 g/d, group‐by‐time interaction P = 0.01). Similar patterns of intake occurred for isoleucine and valine.ConclusionsConsuming ~3g/kg/d of total protein with meat or dairy as the main source in solid foods is feasible in 6–12 months old formula‐fed infants. Protein source or increased quantity did not appear to alter total caloric intake but does alter profile of branch chain amino acids, which may have implications for growth and metabolic outcomes.Support or Funding InformationAmerican Heart AssociationColorado Clinical and Transnational Research Institute National Pork BoardNational Cattlemen's Beef Association Abbott Nutrition Leprino Foods