Isoflavones are a type of phytoestrogen found in high amounts in soy foods. In other words, phytoestrogens can either mimic or block the effect of estrogen. Genistein 1,000 mg Tablets. Other Ingredients: stearic acid, dibasic calcium phos-phate, colloidal silicon dioxide, sorbitol, modified cell-ulose gum and magnesium stearate.