To the Editor: A recent editorial [1] properly credited Franke and Custer [2] for an important study of urinary and breast milk concentrations of isoflavones in women consuming soybeans. This editorial cited literature concerning potential health benefits of phytoestrogens and, to a much lesser extent, potential toxicity. In the accompanying letter below, Franke points out that infants consuming soy-based formula are exposed to high concentrations of phytoestrogens.
