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

Tang and Krebs 2014.

Methods Study design: randomized controlled trial
 Study duration: 5 months
Start date: January 2008
End date: September 2010
Participants Country and setting: USA (high‐income country); Denver, Colorado metro area
Population: not reported
Inclusion criteria:

  1. exclusive breastfeeding

  2. infant born at term with birthweight appropriate for gestational age


Exclusion criteria:

  1. current or planned formula use

  2. low birthweight

  3. use of vitamin‐mineral supplements (excluding vitamin D)

  4. significant congenital anomalies

  5. known chronic conditions that would affect feeding, growth, or development potential


Nutritional status: baseline mean LAZ: −0.66 in intervention group, −0.10 in control group
Number: 42
Age: 6 months at beginning of intervention
Sex: 17 boys, 25 girls (differentiation between intervention and control groups not provided)
Typical diet: not provided
Interventions Intervention: puréed meat and gravy; provision of 1 jar (71 g in total) by 7 months of age and 1 to 2 jars/d by 9 months of age
Control: zinc‐ and iron‐fortified cereal; provision of 1 serving/d (15 g) by 7 months of age and 2 servings/d by 9 months of age
Outcomes Primary:

  1. zinc

  2. iron status


Reported in separate studies (Krebs 2012b; Krebs 2013)
Secondary:

  1. linear growth

  2. blood biomarkers, including insulin‐like growth factor‐1, leptin, glucose, insulin, high‐density lipoprotein, and triglycerides


Measurement:

  1. linear growth: "Length was measured in a recumbent position by using an infant stadiometer accurate to 0.1 cm (Holtain Ltc). An electronic digital balance (Sartorious Corp) was used to obtain naked infant weight."

  2. blood samples: morning blood samples collected, centrifuged, and stored at −80 °C; analyzed by Colorado Clinical and Translational Science Institute's Core Laboratory


Time points: 5, 6, 7, 8, 9 months of age
Notes Funding: supported by the Beef Checkoff through the National Cattlemen’s Beef Association and the National Institutes of Health (K24 DK083772)
Declared conflict of interest: none declared
Other notes: infants in the cereal group were instructed to avoid single‐ingredient meats. The authors note that this study was a secondary analysis on growth of a randomized controlled trial designed to compare the effects of fortified cereal and meat on zinc homeostasis and iron status in breastfed‐only infants (Krebs 2012b; Krebs 2013).
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Low risk Comment: randomization and assignment to study group was accomplished using a random number generating program by statistician with no contact with field team
Allocation concealment (selection bias) Low risk Comment: central assignment by statistician who had no contact with field team
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: anthropometric outcome measures obtained by research nurses with no knowledge of group assignment
Incomplete outcome data (attrition bias) 
 All outcomes Low risk Comment: attrition rates were balanced between groups (approximately 14%), and all reasons specified and balanced between groups
Selective reporting (reporting bias) Low risk Comment: all prespecified outcomes reported
Other bias Unclear risk Comment: funding partially provided by National Cattlemen's Beef Association

CDC: Centers for Disease Control and Prevention
 DRI: dietary reference intake
 HAZ: height‐for‐age z score
 LAZ: length‐for‐age z score
 LMIC: low‐ and middle‐income country (or countries)
 SAM: severe acute malnutrition
 WAZ: weight‐for‐age z score
 WHO: World Health Organization