Table 3.
Selected characteristics of the included studies
| Author, year (ordered by study design and alphabetical order of first author) | Country | Design | Treatment/exposures | Dietary assessment methods | Participants, N | Age at inclusion/start of intervention | Follow-up time | Type of outcomes | Confounders adjusted for |
|---|---|---|---|---|---|---|---|---|---|
| Krebs, 2006 (25) | USA | Randomized controlled trial (RCT) | Meat (10.7 g protein/day) vs. cereal (3.3 g protein/day) as exclusive complementary foods for maximum 2 months, and then allowed to include more types. | Food records | 88 | 5 months (most started at 6 months of age) | 7 months | Weight gain and linear growth (g/month, cm/month) | NA |
| Larnkjær, 2009 (26) | Denmark | RCT | Whole milk vs. standard infant formula + fish oil vs. placebo. Breastfeeding optional. |
Food records | 94 | 9 months | 3 months | Weight gain and linear growth (g/month, cm/month) | NA |
| Svahn, 1999 (24) | Sweden | RCT | Milk with different protein and fat contents (2.2–3.3 g/100 ml protein) | Food records | 38 | 12 months | 6 months | Weight gain and linear growth (g/day, mm/day) | NA |
| Tang, 2014 (27) | USA | RCT | Meat (1–2 glasses à 8 g protein) vs. cereal as complementary foods. | Food records, duplicate diets | 42 | 6 months | 3 months | BMIz, weight-for-age z-score (WAZ), weight-for-length z-score (WLZ), and length-for-age z-score (LAZ), and waist circumference (cm) | NA |
| Tang, 2019 (28, 29) | USA | RCT | Meat vs. dairy as complementary foods (both groups ~4 g/kg body weight [BW] protein) from 5 to 12 months of age. | Food records | 53 | 5 months | ≤19 months | Weight (kg), WAZ, WLZ, length (cm), and LAZ | NA |
| Beyerlein, 2017 (43) | USA, Finland, Germany, and Sweden | Prospective cohort (PC) | Total protein (percentage of energy intake [E%]) At 6 months: mean ~8.4 E%, at 12 months: ~13.8 E%, at 2 years: 15.1 E%, at 3 years: 14.7 E%, at 4 years: 14.8 E%, at 5 years: 14.6 E%. |
3-day food records every 3–6 month | 5,563 | 3 months | 5 years | Weight, length, BMIz, and overweight/obesity | Sex, country, birthweight, maternal age, maternal pre-pregnancy Body Mass Index, gestational weight gain, maternal diabetes, maternal smoking in pregnancy, maternal alcohol intake in pregnancy, maternal education, and duration of breastfeeding |
| Braun, 2016 (39) | The Netherlands (Generation R) | PC | Total protein (mean 42.1 g; 12.9 E%) Animal protein (mean 26.5 g; 8.1 E%) Plant protein (mean 15.1 g; 4.7 E%) Amino acids |
Food Frequency Questionnaire (FFQ) | 3,564 | 1 years | 8 years | Weight, height, and BMIz. | Sex, ethnicity, age, energy intake breastfeeding, playing sports, household income maternal BMI at enrolment, maternal education, folic acid use during pregnancy, smoking during pregnancy, and diet score |
| Durao, 2017 (44) | Portugal | PC | Total protein (mean 18.8 E% in girls (4.4 g/kg bw), 18.6 E% (4.5 g/kg bw) in boys at 4 years of age) | 3-day food diaries | 1,999 | 4 years | 3 years | BMIz, weight, length, body fat, and waist circumference. | Total energy intake, maternal education, maternal BMI, birthweight, gestational age, breastfeeding, physical exercise |
| Garden, 2011 (37) | Australia | PC | Total protein Food groups |
3-day weighed food records | 362 | 18 months | 6.5 years | BMI, overweight (BMI ≥85th %), obesity (BMI≥95th %), waist circumference | Sex, asthma study intervention group, birth weight, breastfeeding for at least 6 months, parental obesity, ethnicity, smoking in pregnancy, and father’s education, and total energy. |
| Gunnarsdottir, 2003 (31) | Iceland | PC | Total protein (mean ~8–9 E% at 2–6 months, 15–16 E% at 9–12 months) | 48-h food records | 90 | 2 months | 6 years | BMI and overweight/obesity | Total energy and macronutrients |
| Günther, 2007 (34, 35) | Germany | PC | Total protein, animal protein, vegetable protein, dairy protein, meat protein, cereal protein (E%) (median total intake, 2.1 g/kg BW at 6 months, 2.7 g/kg BW at 12 months (9.8 and 13.3 E%) | 3-day weighed food records | 203 | 3–6 months | 7 years | Weight, height, BMIz, overweight, and over fatness | Total energy, total fat intake, presence of siblings, maternal overweight and BMIz at baseline |
| Hoppe, 2004 (32) | Denmark | PC | Total protein (median 2.7 g/kg BW; ~13 E%) | 5-day weighed food record | 105 | 9 months | ~9 years | Weight, height, BMI, and %BF, | Sex, parental size, and body size at 9 months. |
| Jen, 2019 (48) | The Netherlands (Generation R) | PC | Total protein (mean 42.1 g; 12.9 E%) Animal protein (mean 26.5 g; 8.1 E%) Plant protein (mean 15.1 g; 4.7 E%) |
FFQ | 3,573 | 1 years | 9 years | Weight, height, BMIz, fat mass index (FMI), and fat-free mass index (FFMI) | Sex, ethnicity, age, total energy, birth weight SD score, breastfeeding, diet quality, screening time, playing sports, protein intake. |
| Rolland-Cachera, 1995 (4) | France | PC | Total protein (mean 16.3 E%) | Diet history and 24-h recall | 112 | 2 years | 6 years | BMI, skinfold thickness, and rebound of BMI | Baseline BMI and parental BMI |
| Morgen, 2018 (46) | Denmark | PC | Animal protein (meat and fish, dairy protein) | Interviews | 36,481 | 6 months | 6.5–10.5 years | BMI and overweight/obesity | Maternal pre-pregnancy BMI, gestational weight gain, ponderal index standardized score (SDS) at birth, BMI SDS at 5 months, BMI SDS at 12 months, SES, parity, smoking during pregnancy, and paternal BMI, |
| Öhlund, 2010 (36) | Sweden | PC | Total protein (mean 12.8 E%; 3.96 g/kg at 12 months of age) | 5-day food records monthly from 6 to 18 months of age | 127 | 6 months | 3.5 years | Weight, height, and BMIz | Unclear |
| Pimpin, 2016 (42) | UK (Gemini) | PC | Total protein (median 15.8 E%) | 3-day diet records | 2,154 | 8 months | ~4 years | Weight, height, BMI, and overweight/obesity | Height, total energy intake, sex, age, birth weight, and previous growth |
| Pimpin, 2018 (45) | UK (Gemini) | PC | Total protein Animal protein, dairy protein, milk protein, plant protein |
3-day diet records | 1,939 | 8 months | ~4 years | Weight, height, BMI, and overweight/obesity | Height, total energy intake, sex, age, birth weight, previous growth, and fat intake |
| Scaglioni, 2000 (30) | Italy | PC | Total protein (20–22 E%) | FFQ, interviews | 147 | 1 years | 4 years | Overweight (BMI ≥ 90th %) | None |
| Skinner, 2004 (33) | USA | PC | Total protein (mean 14 E%) | 24-h dietary recall | 70 | 2 years | 6 years | Weight, height, BMI | Unclear |
| Smith-Brown, 2018 (47) | Australia | PC | Protein-rich foods (animal foods, meat/fish/eggs, dairy products) | FFQ | 36 | 12 months | 1–2 years | BMIz, fat mass (FM), fat-free mass | None |
| Switkowski, 2019 (49) | USA | PC | Total protein (mean 58.3 g/day; 3.77 g/kg bw). Animal protein |
FFQ | 1,165 | 3.2 years (median) | 4.5–10 years (median) | BMIz, skinfold thickness, FM, and LBM | Race, age, household income, maternal education, breastfeeding, maternal and paternal BMI, birth weight for GA z-score, fast food intake, and physical activity. |
| Thorisdottir, 2014 (38) | Iceland | PC | Total protein (mean 14.5 E%; 3 g/kg BW) Animal, dairy, meat. and fish (9.9 E%) Vegetable (4.4 E%) |
3-day weighed food record | 199 | 12 months | 5 years | Weight, height, and BMI | Sex, energy intake, breastfeeding duration, maternal education, and birth weight. |
| Voortman, 2016 (40, 41) | The Netherlands (Generation R) | PC | Total protein (mean 42.1 g; 12.9 E%) Animal protein (mean 26.5 g; 8.1 E%) Plant protein (mean 15.1 g; 4.7 E%) |
FFQ | 2,965 | 1 year | 5 | Weight, height, BMIz, % body fat SDS, FMI SDS, and FFMI SDS. | Energy intake (nutrient residual method), sex, age at outcome measurement, household income, maternal age, education, BMI and smoking during pregnancy, child’s ethnicity, birth weight SDS, breastfeeding total fat intake, diet quality score, screen time and sports participation (+ BMI SDS at 1 year of age). |