NTP-CERHR monograph on Soy Infant Formula

Soy infant formula contains soy protein isolates and is fed to infants as a supplement to or replacement for human milk or cow milk. Soy protein isolates contains estrogenic isoflavones ("phytoestrogens") that occur naturally in some legumes, especially soybeans. Phytoestrogens are non-steroidal, estrogenic compounds. In plants, nearly all phytoestrogens are bound to sugar molecules and these phytoestrogen-sugar complexes are not generally considered hormonally active. Phytoestrogens are found in many food products in addition to soy infant formula, especially soy-based foods such as tofu, soy milk, and in some over-the-counter dietary supplements. Soy infant formula was selected for evaluation by the National Toxicology Program (NTP) because of the: (1)availability of large number of developmental toxicity studies in laboratory animals exposed to the isoflavones found in soy infant formula (namely, genistein) or other soy products, as well as a number of studies on human infants fed soy infant formula, (2)the availability of information on exposures in infants fed soy infant formula, and (3)public concern for effects on infant or child development. The NTP evaluation was conducted through its Center for the Evaluation of Risks to Human Reproduction (CERHR) and completed in September 2010. The results of this soy infant formula evaluation are published in an NTP Monograph. This document contains the NTP Brief on Soy Infant Formula, which presents NTP's opinion on the potential for exposure to soy infant formula to cause adverse developmental effects in humans. The NTP Monograph also contains an expert panel report prepared to assist the NTP in reaching conclusions on soy infant formula. The NTP concluded there is minimal concern for adverse effects on development in infants who consume soy infant formula. This level of concern represents a "2" on the five-level scale of concern used by the NTP that ranges from negligible concern ("1") to serious concern ("5"). This conclusion was based on information about soy infant formula provided in the expert panel report, public comments received during the course of the evaluation, additional scientific information made available since the expert panel meeting in December 2009, and peer reviewer critiques of the draft NTP Brief by the NTP Board of Scientific Counselors on May 10, 2010.