Glycitein

Glycitein binds weakly to human estrogen receptors, especially estrogen receptor beta. This selective binding lets it produce mild estrogen-like effects in some tissues while blocking stronger endogenous estrogens in others, depending on the local receptor distribution and hormone levels. Like other isoflavones, glycitein is also a free-radical scavenger and may influence enzymes involved in inflammation and cholesterol metabolism. It is usually present at a much lower concentration than genistein or daidzein in soy products, so its individual contribution to the effects attributed to 'soy isoflavones' is harder to isolate.

There is no established RDA or UL for glycitein. Standardized soy isoflavone supplements typically deliver 40-80 mg total isoflavones per day, of which glycitein usually makes up 5-10%. Pure glycitein supplements are uncommon.

Glycitein (within an isoflavone supplement) can be taken with or without food, though taking it with a meal may reduce stomach upset. There is no clear preference for morning or evening dosing.

Soy isoflavones, including glycitein, are generally well tolerated at typical dietary and supplemental doses. Side effects, when reported, include mild gastrointestinal upset. Long-term safety data specifically for isolated glycitein are limited; most safety information comes from studies of mixed soy isoflavones.

Soy isoflavones may interact with tamoxifen and other hormone-sensitive cancer therapies, though the clinical significance is debated. They may also modestly affect thyroid medication absorption when taken at the same time.