Children's HealthEndocrine Function

New Research Published on Soy Infant Formula

Woman Preparing Soy Infant Formula At Table.

Sales and prescription data indicate that specialized infant formulas have become much more common in the United Kingdom, Norway, and Australia over the past two decades.1 In contrast, there has been a rather marked decline in the use of soy infant formula (SIF). If concerns about SIF’s impact on normal growth and development or adverse effects later in life have caused this decline, new research which suggests these concerns are unfounded may provide helpful information.2

A team of European and Australian researchers used national prescription databases to determine trends in the use of specialized infant formulas, which refers to breastmilk substitute products for infants with cow’s milk allergy.1 Community prescription data were available from England (1991–2020), Norway (2009–2020) and Australia (1992–2020). Data for extensively hydrolyzed formulas (EHF) and amino-acid formula (AAF) were available from all three countries and data for SIF formula were from England and Norway only. Prescribed volumes of specialized formula for infants rose 2.8-fold in England from 2007 to 2018, 2.2-fold in Norway from 2009 to 2020, and 3.2-fold in Australia from 2001 to 2012.

In contrast, SIF use in England markedly decreased as illustrated in the graph. In this graph, predicted volumes are the lower to the upper bound range of expected total specialized formula consumption. These volumes are based on 1% of live births each year with milk allergy, population-based formula feeding rates from the 2005 and 2010 United Kingdom National Infant Feeding Survey, and estimated daily formula consumption of 780mL at 0–5.9 months and 600mL at 6–11.9 months.

Volume of reimbursed specialized infant formulas for under 1-year-old with milk allergy in England


The authors of this study suggest that specialized infant formula is overdiagnosed because there is little evidence in high-income countries for a change in milk allergy incidence,3 which is approximately 1%.4  The peak year for SIF use in England was 1994, when volumes were 5.5–6.4 times greater than expected volume. However, by 2020, SIF represented less than 1% of reimbursed specialized formula volumes.

Mehta et al.1 attributed the decline in SIF use to concerns about soy isoflavones potentially adversely affecting endocrine development, especially thyroid and reproductive functions, and to national governments recommending against the use of SIF. However, there has also been a lot of discussion over the past 20 years about the value of SIF as a suitable substitute for infants with cow’s milk allergy. Generally, recommendations are that at least during the first six months of life, infants allergic to cow’s milk should use EHF, not SIF5-8 because a subset of infants (~14%) will develop soy allergy.9

If concerns over endocrine disruption have led to a decrease in SIF use, a recent paper from Ronis and colleagues2 may be especially consequential. For this study, male piglets received either sow milk, milk formula, SIF, or milk formula supplemented with estradiol or genistein from postnatal day 2 until day 21.

Estrogen administration led to clear estrogenic effects. Estrogen reduced testis weight as percentage of body weight, significantly suppressed serum androgen concentrations, increased tubule area, and Germ cell and Sertoli cell numbers and decreased blood testosterone levels relative to those of piglets given sow milk or cow’s milk. SIF and milk plus genistein had no such effects relative to the sow or milk groups. Furthermore, with respect to gene expression, there was very little overlap between the estrogen group and the SIF group. Ronis et al.2 concluded that SIF is not estrogenic in the male neonatal piglet and that SIF does not significantly alter male reproductive development.

Finally, because there is concern about mineral absorption, SIFs are fortified with iron and zinc.7 New research from Brazil shows that based on an in vitro method, the absorption of iron and zinc varied quite markedly between the two SIFs examined.10 More specifically, in one formula, iron and zinc absorption was 83 and 78%, respectively, versus 35 and 31%, respectively, for the other formula. However, when considering the iron and zinc content of both formulas, mineral status will not likely be adversely affected as a result of the consumption of either SIF.

In summary, while SIF use has declined in Europe for likely various reasons, recent research may help to allay concerns that SIF exerts estrogenic effects or impairs mineral status.

References

  1. Mehta S, Allen HI, Campbell DE, Arntsen KF, Simpson MR, Boyle RJ. Trends in use of specialized formula for managing cow’s milk allergy in young children. Clin Exp Allergy 2022;52:839-47.
  2. Ronis MJJ, Gomez-Acevedo H, Shankar K, Hennings L, Sharma N, Blackburn ML, Miousse I, Dawson H, Chen C, Mercer KE, et al. Soy formula is not estrogenic and does not result in reproductive toxicity in male piglets: Results from a controlled feeding study. Nutrients 2022;14.
  3. Munblit D, Perkin MR, Palmer DJ, Allen KJ, Boyle RJ. Assessment of Evidence About Common Infant Symptoms and Cow’s Milk Allergy. JAMA Pediatr 2020;174:599-608.
  4. Schoemaker AA, Sprikkelman AB, Grimshaw KE, Roberts G, Grabenhenrich L, Rosenfeld L, Siegert S, Dubakiene R, Rudzeviciene O, Reche M, et al. Incidence and natural history of challenge-proven cow’s milk allergy in European children–EuroPrevall birth cohort. Allergy 2015;70:963-72.
  5. Matthai J, Sathiasekharan M, Poddar U, Sibal A, Srivastava A, Waikar Y, Malik R, Ray G, Geetha S, Yachha SK, et al. Guidelines on diagnosis and management of cow’s milk protein allergy. Indian Pediatr 2020;57:723-9.
  6. Agostoni C, Axelsson I, Goulet O, Koletzko B, Michaelsen KF, Puntis J, Rieu D, Rigo J, Shamir R, Szajewska H, et al. Soy protein infant formulae and follow-on formulae: A commentary by the ESPGHAN committee on nutrition. J Pediatr Gastroenterol Nutr 2006;42:352-61.
  7. Bhatia J, Greer F. Use of soy protein-based formulas in infant feeding. Pediatrics 2008;121:1062-8.
  8. Koletzko S, Niggemann B, Arato A, Dias JA, Heuschkel R, Husby S, Mearin ML, Papadopoulou A, Ruemmele FM, Staiano A, et al. Diagnostic approach and management of cow’s-milk protein allergy in infants and children: ESPGHAN GI Committee practical guidelines. J Pediatr Gastroenterol Nutr 2012;55:221-9.
  9. Zeiger RS, Sampson HA, Bock SA, Burks AW, Jr., Harden K, Noone S, Martin D, Leung S, Wilson G. Soy allergy in infants and children with IgE-associated cow’s milk allergy. J Pediatr 1999;134:614-22.
  10. Moraes MR, do Nascimento da Silva E, Sanches VL, Cadore S, Godoy HT. Bioaccessibility of some minerals in infant formulas. Journal of food science and technology 2022;59:2004-12.

 This blog is sponsored by SNI Global and U.S. Soy.

Dr. Mark Messina

Author Dr. Mark Messina

PhD in Nutrition, Director of Nutrition Science and Research, Soy Nutrition Institute Global. Expert in soyfoods and isoflavones.

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