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A panel of 14 independent experts convened by the US Center for the Evaluation of Risks to Human Reproduction (CERHR) and the National Toxicology Program (NTP) determined that the phytoestrogen genistein found in soybeans does not pose a reasonable threat to human reproduction and development, based on available data. The panel noted that insufficient data exists, however, to permit a determination of the safety of soy infant formula.1
During a 3-day meeting, held March 15-17 in Alexandria, VA, the panel reviewed studies of laboratory animals and humans to determine whether genistein or soy formula might cause adverse effects on human reproduction and/or development of a fetus or infant. The panel ultimately expressed negligible concern for reproductive and developmental effects from exposure of adults, who they claim are unlikely to consume daily levels of genistein sufficient to cause adverse effects in such areas. The panel members further expressed negligible concern for adverse effects in neonates and infants who consume up to 0.01-0.08 mg/kg bw/day of genistein (the aglycone form of genistin) contained in soy formula. Of the total amount of genistein/genistin in soy formula only about 1% is present in the uncomplexed aglycone form. With respect to soy formula’s overall reproductive or developmental toxicity, the panel argued that poor study designs, insufficient sample sizes, and otherwise insufficient data of case-studies and trials prevented its members from arriving at a clear determination of safety.
The full genistein and soy formula expert panel reports are available at the CERHR Web site, at http://cerhr.niehs.nih.gov/. CERHR and NTP are jointly preparing monographs of genistein and soy formula, based on the panel’s findings and public comments submitted to CERHR by July 5. The monographs will be available to the public on the CERHR Web site and distributed to appropriate federal health and regulating agencies.
A recent editorial by Kenneth D.R. Setchell, PhD, professor of pediatrics at the University of Cincinnati College of Medicine, addressed the panel’s findings.2 According to Dr. Setchell, soy formula’s 40-year history of use with little documentation of adverse effects attests to its safety. He further pointed out that animal testing does not adequately demonstrate the potential effects of soy or genistein on human infants, signaling a need for prospective studies of risks and benefits of soy, in place of further animal trials. According to an article in Environmental Health Perspectives, the world’s largest, longitudinal study of children and their consumption of soy-based formula, cow’s milk-based formula, and breast-milk is currently underway, under the direction of Thomas Badger, PhD, of the Arkansas Children’s Nutrition Center.3
It is estimated that 20-25% of infants in the United States consume soy infant formula at some point during their development.3,4 Soyfood sales reached nearly $4 billion in the United States in 2003 and are expected to continue to rise, according to the Soyfoods Association of North America.5
-Courtney Cavaliere
References
1. Meeting summary: National Toxicology Program Center for the Evaluation of Risks to Human Reproduction: expert panel evaluation of genistein and soy formula March 15-17, 2006. Center for the Evaluation of Risks to Human Reproduction Web site. Available at: http://cerhr.niehs.nih.gov/chemicals/genistein-soy/SoyMeeting%20Summary.pdf. Accessed April 24, 2006.
2. Setchell K. Assessing risks and benefits of genistein and soy. Environmental Health Perspectives. 2006;114(6):332-333.
3. Barrett J. The science of soy. Environmental Health Perspectives. 2006;114(6):353-358.
4. Core J. Study examines long-term health effects of soy infant formula. Agricultural Research. 2004: 52(1);8-10. Available at: http://www.ars.usda.gov/is/AR/archive/jan04/soy0104.pdf. Accessed May 22, 2006.
5. Soy Food Sales and Trends page. Soyfoods Association of North America Web site. Available at: http://www.soyfoods.org/sales/sales.html. Accessed May 22, 2006.
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