We updated our information on soy formula to include recent research.
Both the National Institutes of Health and the American Academy of Pediatrics (AAP) consider soy formula safe for term infants. The AAP specifically recommends soy formula for those seeking a vegetarian or vegan diet for term infants (1).
What’s new in soy formula research:
- A 2017 cross-sectional study found boys who were fed soy formula did not experience suppressed testosterone as infants (as had been previously reported in animal studies) (2).
- A 2018 longitudinal study found girls exclusively fed soy formula in infancy had greater vaginal and uterine maturation indices, but no difference in breast bud diameter or hormone concentrations compared to those receiving cow-based formula (3).
- A 2019 case-control study found no association between the use of soy formula and the age of onset of puberty (4).
- A 2019 retrospective study on African-American women found that women fed soy formula as infants were more likely to report moderate/severe menstrual discomfort/pain with ‘most periods’, but not with ‘every period’, during early adulthood compared to women never fed soy formula (5). Mark Messina, PhD, of the Soy Nutrition Institute, says there’s not enough research on the impact of soy formula consumption on menstrual pain later in life to draw any meaningful conclusions (6).
Soy formula is not recommended for pre-term infants. Babies with thyroid issues may need extra monitoring if they receive soy formula (7).
1. Where We Stand: Soy Formulas. American Academy of Pediatrics healthychildren.org. Updated 8/7/2018.
2. Fang, X., Wang, L., Wu, C. et al. Sex Hormones, Gonadotropins, and Sex Hormone-binding Globulin in Infants Fed Breast Milk, Cow Milk Formula, or Soy Formula. Sci Rep 7, 4332 (2017).
3. Adgent MA, Umbach DM, Zemel BS, et al. A Longitudinal Study of Estrogen-Responsive Tissues and Hormone Concentrations in Infants Fed Soy Formula. J Clin Endocrinol Metab. 2018;103(5):1899–1909.
4. Sinai T, Ben-Avraham S, Guelmann-Mizrahi I, et al. Consumption of soy-based infant formula is not associated with early onset of puberty. Eur J Nutr. 2019;58(2):681–687.
5. Upson K, Adgent MA, Wegienka G, Baird DD. Soy-based infant formula feeding and menstrual pain in a cohort of women aged 23-35 years. Hum Reprod. 2019 Jan 1;34(1):148-154.
6. Messina M. Soy Formula and Menstrual Pain: A Look at the Evidence. Soy Nutrition Institute. Published January 3, 2020.
7. Bhatia J, Greer F; American Academy of Pediatrics Committee on Nutrition. Use of soy protein-based formulas in infant feeding. Pediatrics. 2008 May;121(5):1062-8.