This study was published in Clinical Endocrinoloy 2011 Dec;75(6):831-5
Study title and authors:
High serum isoflavone concentrations are associated with the risk of precocious puberty in Korean girls.
Kim J, Kim S, Huh K, Kim Y, Joung H, Park M.
Department of Food and Nutrition, Daegu University, Gyeongsan, Korea.
This study can be accessed at: http://www.ncbi.nlm.nih.gov/pubmed/21623856?dopt=Abstract
Central precocious puberty is sexual development before the age of eight in girls, and age 10 in boys. The early onset of puberty may cause problems when hormones trigger changes in the growth pattern, essentially halting growth before the child has reached normal adult height. Girls may never grow above 5 ft (152 cm) and boys often stop growing by about 5 ft 2 in (157 cm). Children with this condition look noticeably different than their peers, and may feel rejected by their friends and socially isolated.
The aim of the study was to test the association between the levels of the isoflavones genistein and daidzein, (the major phytoestrogens in soy), and the risk of central precocious puberty. The study included 108 girls with central precocious puberty (average age 8.6 years old) and 91 age-matched controls.
The study found the prevalence of central precocious puberty was significantly higher in children with isoflavone levels above 30 nmol/L than those with isoflavone levels below 30 nmol/L.
The results from this study suggest that elevated levels of the soy isoflavones genistein and daidzein may be associated with an increased risk of central precocious puberty.