Soy Protein-Based Infant Formula Feeding Association with Adolescent Growth, Body Composition, Cardiometabolic Health, and Pubertal Development in Comparison with Cow's Milk-Based Infant Formula and Human Milk Feeding.

Adolescents fed soy protein-based infant formula had similar body weight, BMI-for-age z-score, fat mass index, abdominal adiposity, and waist circumference compared with those fed cow's milk-based formula or human milk.

• Study included 190 participants (SF = 52, HM = 76, MF = 62) assessed at age 14.10 ± 0.26 years (range 13.47–14.96 years).
• Measurements included anthropometry, body composition, visceral and subcutaneous adipose tissue areas, and waist circumference.
• Statistical analyses used generalized linear regression models adjusted for age, sex, race/ethnicity, mother's education, and birth characteristics.
• No significant differences were found between groups in any of the adiposity or growth measures.

Fat intake as a percentage of kilocalories was lower in participants fed soy protein-based infant formula and human milk as infants compared with those fed cow's milk-based formula.

• Energy intake, macronutrient intakes overall, and diet quality (Healthy Eating Index-2020) were comparable across all three feeding groups.
• The difference in fat intake (%kcal) was statistically significant for the SF and HM groups compared with MF.
• Dietary intake was assessed at age 14 years.

There were no significant differences between feeding groups in blood pressure, glucose metabolism, lipid profile, or inflammatory biomarkers at age 14 years.

• Cardiometabolic biomarkers assessed included blood pressure, glucose metabolism markers, lipid profile, and inflammatory biomarkers.
• Analyses were adjusted for age, sex, race/ethnicity, mother's education, and birth characteristics.
• All three feeding groups (SF, MF, HM) were compared.

The prevalence of cardiometabolic risk factors was significantly higher in participants fed cow's milk-based infant formula (8.1%) compared with soy protein-based formula (3.8%) and human milk (0.0%).

• Cardiometabolic risk factor prevalence was 8.1% for MF-fed, 3.8% for SF-fed, and 0.0% for HM-fed participants.
• The difference was described as statistically significant across groups.
• This was assessed at age 14 years in the Beginnings follow-up study.

There were no significant differences between infant feeding groups in pubertal stage, age of menarche, or reproductive organ sizes and characteristics at age 14 years.

• Pubertal development assessments included pubertal stage, age of menarche, and reproductive organ volumes and characteristics.
• Participants included both male and female adolescents across the three feeding groups.
• Analyses were adjusted for age, sex, race/ethnicity, mother's education, and birth characteristics.

Human milk feeding during infancy was protective against adolescent adiposity compared with cow's milk-based formula feeding in adjusted models.

• This finding was observed in generalized linear regression models adjusted for age, sex, race/ethnicity, mother's education, and birth characteristics.
• The HM group comprised 76 participants out of the total 190.
• Human milk feeding was associated with lower adiposity measures compared specifically with MF feeding.

Approximately 12% of infants in the United States are fed soy protein-based infant formulas, yet long-term health data comparing SF with MF and HM remain limited.

• The study was designed to address this evidence gap by following participants from infancy to age 14 years.
• The Beginnings follow-up study (NCT03108014) was used as the study framework.
• Outcomes assessed included growth, adiposity, dietary intake, metabolic health, and pubertal development.