Safety and pharmacokinetics of purified soy isoflavones: single-dose administration to postmenopausal women.

Background: Soy isoflavones are being evaluated as chemopreventive agents for breast and other cancers.

Objective: The objective was to perform safety and pharmacokinetic studies of purified unconjugated isoflavone preparations containing genistein, daidzein, and glycitein in postmenopausal women.

Design: Twenty-four healthy postmenopausal women ingested a single dose of 1 of 2 purified (from soybeans) isoflavone preparations that delivered a genistein dose of 2, 4, 8, or 16 mg/kg body wt.