Soy Isoflavones
Soy isoflavones are plant compounds in soybeans, mainly genistein, daidzein and glycitein. Because they resemble estrogen in structure, they are called phytoestrogens.
Also listed as Genistein, Genistin, Daidzein, Daidzin
The safety guidance has boundaries
BfR cites up to 100 mg soy isoflavones daily for up to ten months as orientation values for healthy postmenopausal women. These are not a recommended dose or proof of indefinite safety. BfR advises against isolated supplements with a current or previous estrogen-dependent breast or uterine disease. 1
Food and concentrated supplements deserve separate judgments
NCCIH reports that soy foods appear safe for women with a history of breast cancer, while supplement safety in this group remains uncertain. It also notes a possible risk of thickening of the uterine lining with long-term isoflavone supplementation, without the same signal for soy foods. 2
Allergy and pregnancy still matter
Soy allergy remains relevant to soy-based products. NCCIH cautions that amounts beyond ordinary food use may be unsafe during pregnancy; safety during breastfeeding is poorly understood. 3
For information, not individual medical advice. Ingredient studies do not establish the effectiveness of these products.