Moderate evidenceWomen's health

Genistein

The isolated soy isoflavone with the most bone data behind it. Effects on bone density are consistent but small, and menopausal symptom relief is real but modest.

Evidence last reviewed: August 2026

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What the science says

Bone mineral density Moderate evidence
A follow-up of a randomized trial of genistein aglycone in postmenopausal women with bone loss reported increases in bone mineral density over three years without adverse breast effects, and a systematic review and meta-analysis of isoflavone trials found a small overall benefit for bone mineral density.
Menopausal symptoms Moderate evidence
A multi-center randomized placebo-controlled trial of synthetic genistein in healthy postmenopausal women reported reduced hot flash frequency. The size of the effect is smaller than with hormone therapy.

Dosage & safety

Studied doseBone trials used 54 mg of genistein aglycone daily; menopause symptom trials used around 30 mg daily. Effects on bone were seen over 12-36 months.

SafetyDigestive upset is the most common complaint. Genistein is estrogenic, and although trial follow-up found no adverse breast effects, women with hormone-sensitive cancers or on tamoxifen should not self-prescribe it. Avoid in pregnancy and breastfeeding; may interfere with thyroid function at high intakes when iodine is low.

Scientific references

Breast safety and efficacy of genistein aglycone for postmenopausal bone loss: a follow-up study
Marini H, Bitto A, Altavilla D, Burnett BP, Polito F, Di Stefano V — J Clin Endocrinol Metab, 2008
Isoflavone intervention and its impact on bone mineral density in postmenopausal women: a systematic review and meta-analysis of randomized controlled trials
Inpan R, Na Takuathung M, Sakuludomkan W, Dukaew N, Teekachunhatean S, Koonrungsesomboon N — Osteoporos Int, 2024
The effect of synthetic genistein on menopause symptom management in healthy postmenopausal women: a multi-center, randomized, placebo-controlled study
Evans M, Elliott JG, Sharma P, Berman R, Guthrie N — Maturitas, 2011

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