Early-life soy exposure and age at menarche

• Type of Material: Article
• Authors: Margaret Adgent, National Institute of Environmental Health Sciences; Julie Daniels, University of North Carolina; Walter Rogan, National Institute of Environmental Health Sciences; Linda Adair, University of North Carolina; Lloyd Edwards, University of North Carolina; Daniel Westreich, University of North Carolina; Mildred Maisonet, Emory University; Michele Marcus, Emory University
• Language: English
• Date: 2012-03-01
• Publisher: Wiley: 12 months
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © Published 2011. This article is a U.S. Government work and is in the public domain in the USA.
• Final Published Version (URL): http://dx.doi.org/10.1111/j.1365-3016.2011.01244.x
• Title of Journal or Parent Work: Paediatric and Perinatal Epidemiology
• ISSN: 0269-5022
• Volume: 26
• Issue: 2
• Start Page: 163
• End Page: 175
• Grant/Funding Information: The UK Medical Research Council (Grant Ref: 74882); the Wellcome Trust (Grant Ref: 076467); and the University of Bristol provide core support for ALSAPC.; The research was specifically funded by NICHD/NIH (T32HD052468-01A2), 2008–2013; the Intramural Research Program of the NIH; and Centers for Disease Control and Prevention.
• Keywords: soy milk; PROTEIN; ALSPAC; infant diet; Obstetrics & Gynecology; IN-VITRO; menarche; RATS; Public, Environmental & Occupational Health; Life Sciences & Biomedicine; ESTROGEN-RECEPTOR-ALPHA; HYPOTHALAMUS; ISOFLAVONES; BETA; Pediatrics; PHYTOESTROGEN GENISTEIN; FORMULA; Science & Technology; GIRLS; endocrine disruptor
• Research Categories: Health Sciences, Epidemiology; Health Sciences, Obstetrics and Gynecology; Health Sciences, Public Health

Abstract

This study examines the timing of menarche in relation to infant-feeding methods, specifically addressing the potential effects of soy isoflavone exposure through soy-based infant feeding. Subjects were participants in the Avon Longitudinal Study of Parents and Children (ALSPAC). Mothers were enrolled during pregnancy and their children have been followed prospectively. Early-life feeding regimes, categorised as primarily breast, early formula, early soy and late soy, were defined using infant-feeding questionnaires administered during infancy. For this analysis, age at menarche was assessed using questionnaires administered approximately annually between ages 8 and 14.5. Eligible subjects were limited to term, singleton, White females. We used Kaplan-Meier survival curves and Cox proportional hazards models to assess age at menarche and risk of menarche over the study period. The present analysis included 2920 girls. Approximately 2% of mothers reported that soy products were introduced into the infant diet at or before 4 months of age (early soy). The median age at menarche [interquartile range (IQR)] in the study sample was 153 months [144-163], approximately 12.8 years. The median age at menarche among early soy-fed girls was 149 months (12.4 years) [IQR, 140-159]. Compared with girls fed non-soy-based infant formula or milk (early formula), early soy-fed girls were at 25% higher risk of menarche throughout the course of follow-up (hazard ratio 1.25 [95% confidence interval 0.92, 1.71]). Our results also suggest that girls fed soy products in early infancy may have an increased risk of menarche specifically in early adolescence. These findings may be the observable manifestation of mild endocrine-disrupting effects of soy isoflavone exposure. However, our study is limited by few soy-exposed subjects and is not designed to assess biological mechanisms. Because soy formula use is common in some populations, this subtle association with menarche warrants more in-depth evaluation in future studies.