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. 2019 Feb 19;2019(2):CD012818. doi: 10.1002/14651858.CD012818.pub2

Tang 2018a.

Methods Study design: randomized controlled trial
 Study duration: 7 months
Start date: September 2013
End date: August 2016
Participants Country and setting: USA (high‐income country); Denver, Colorado metro area
Population: not reported
Inclusion criteria:

  1. formula‐fed

  2. infant born at term


Exclusion criteria:

  1. low birthweight

  2. cumulative breastfeeding > 1 month

  3. significant congenital anomalies or known chronic diseases


Nutritional status: baseline weight: 7.37 (± 0.67) in meat intervention group, 7.35 (± 0.74) in dairy control group; no significant differences between groups
Number: 64 (32 in meat intervention group, 32 in dairy control group)
Age: 5 months at enrollment
Sex: 45% male in meat intervention group, 48% male in dairy control group
Typical diet: formula‐fed. Fruit and vegetable intake were not restricted.
Interventions Intervention: meat; commercially available puréed meats
Control: dairy; infant yogurt, cheese, and a powdered concentrate of 80% whey protein
In both groups, either a meat or dairy‐based suite of foods were provided to parents. Parents were provided with tailored feeding guidelines and were encouraged to let the infant's appetite dictate their total intake.
Outcomes Primary:

  1. growth, including longitudinal changes in weight (kilograms), length (centimeters)

  2. age‐specific z scores

  3. sex‐specific z scores


Secondary:

  1. insulin‐like growth factor I (IGF‐I)

  2. insulin‐like growth factor‐binding protein 3 (IGFBP3)

  3. blood urea nitrogen (BUN)


Measurement:

  1. "Length was measured in the recumbent position by using an infant stadiometer accurate to 0.1 cm (Holtain Ltd.). An electronic digital balance (Sartorious Corp.) was used to obtain naked infant weight. z Scores were calculated on the basis of WHO/CDC growth standards."

  2. "Blood samples were collected at baseline and at the end of the intervention. Samples sit at room temperature for 30 min and were centrifuged at 1500 × g for 10 min and serum was stored at −80°C until analysis. The following markers were analyzed by the Colorado Clinical and Translational Science Institute’s Core Lab: IGF‐I (chemiluminescence; DiaSorin Liaison), IGFBP3 (chemiluminescence; Siemen), and BUN. The between assay precisions were <2.7% for IGF‐I, <4.0% for IGFBP3, and <4.5% for BUN."


Time points:

  1. growth measured at 7, 8, 9, 10, 11, and 12 months of age

  2. blood biomarkers measured at baseline (5 months) and endline (12 months)
Notes Funding: supported by the National Institutes of Health (NIH) (National Institute of Diabetes and Digestive and Kidney Diseases; 1K01DK111665), NIH/National Center for Advancing Translational Sciences (NCATS) Colorado Clinical and Translational Science Awards (CTSA; grant UL1 TR001082), and (alphabetically) Abbott Nutrition, the American Heart Association, the Beef Checkoff through the National Cattlemen’s Beef Association, Leprino Foods, and the National Pork Board
Declared conflict of interest: none declared
Other notes: "Only exclusively formula‐fed infants were chosen 1) to increase internal validity because breast‐ and formula‐fed infants pose different risks to rapid weight gain and may respond differently to complementary feeding, 2) because formula‐fed infants are at higher risk of excessive weight gain, and 3) because the majority of infants in the United States are formula‐fed, especially after 3 mo of age"
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Low risk Comment: computer‐generated assignment
Allocation concealment (selection bias) Low risk Quote: "Upon recruitment to the study, participants were matched to another participant with the use of 10 race/ethnicity categories. The treatment assignment for the first participant in each matched pair was randomly assigned in Microsoft Excel"
Blinding of participants and personnel (performance bias) 
 All outcomes Low risk Comment: unable to blind but unlikely to have affected outcome
Blinding of outcome assessment (detection bias) 
 All outcomes Low risk Comment: growth measurements conducted by nurses blinded to infants' feeding group
Incomplete outcome data (attrition bias) 
 All outcomes Low risk Comment: attrition rate ˜15% and relatively even between groups
Selective reporting (reporting bias) Low risk Comment: all stated outcomes reported
Other bias Unclear risk Comment: partially supported the National Cattlemen's Association, Leprino Foods, and the National Pork Board