Soy Isoflavones
Phytoestrogens from soy: genistein, daidzein, glycitein. Structurally resemble estradiol and weakly bind skin estrogen receptors. Marketing positioning – anti-age for menopausal skin where estrogen decline is linked to loss of firmness and density. Topical evidence base is limited, but safety profile is favourable.
Evidence by route
Topical application
Small clinical studies showed improved skin density and elasticity in postmenopausal women with daily use of 2-4%. Effects are modest and not comparable to prescription topical estrogens. No meta-analyses in dermatology journals.
- Clinical Efficacy of Topical or Oral Soy Supplementation in Dermatology: A Systematic Review. J Clin Med. 2023;12(12):4171.. PMID 37373864
How to read tiers A–F
- CWeak evidence. In vitro data, open-label studies, or expert consensus
Tolerability and safety
- Irritation potential
- Low
- Allergen risk
- Low
- Pregnancy
- Caution
- Suitable for
- Normal, Dry, Combination
- Use with caution
- Sensitive
About this ingredient
Soy Isoflavones (INCI Glycine Soja Extract) are a group of soy phytoestrogens: genistein, daidzein, glycitein. Structurally resemble estradiol and weakly bind skin estrogen receptors (ERβ). Mechanism. Activate ERβ in keratinocytes and fibroblasts, partially mimicking an estrogenic signal. In menopausal women this links to maintenance of collagen and elastin density and slower skin thinning. Isoflavones also act as antioxidants. Where applied. Anti-aging serums and creams (extract 0.5-3%), mature-skin products, 'menopausal skin' lines. In Spain – Sesderma Reti Age, Endocare Cellage, Mesoestetic. Evidence base. Accorsi-Neto 2009 in 30 postmenopausal women showed epidermal collagen and elastin gains over 6 months of 4% soy isoflavones. Other RCTs (Patriarca 2007) confirm hydration and texture improvement. Effect is modest, below retinol. Safety. CIR confirmed safety at cosmetic concentrations. Patients with confirmed soy allergy may show contact reactions. Pregnancy and lactation – use with caution. Topical systemic absorption is minimal, but because of phytoestrogen hormonal activity manufacturers label beauty products with isoflavones as 'not for pregnancy'. For gestational melasma prefer niacinamide, azelaic acid, adenosine. Suitable for. Mature postmenopausal skin, loss of density and firmness, thinning skin on hands and neck. Not for younger patients – effect is weaker than niacinamide and peptides.
Frequently asked questions
Is Soy Isoflavones safe during pregnancy?
Soy Isoflavones should be used with caution during pregnancy. Consulting a dermatologist or OB-GYN is advisable.
What skin types is Soy Isoflavones for?
Soy Isoflavones suits: normal, dry, combination. Use with caution in: sensitive.
What is Soy Isoflavones and what does it do in cosmetics?
Phytoestrogens from soy: genistein, daidzein, glycitein.
What's the INCI name for Soy Isoflavones?
The INCI name is Glycine Soja Extract. It may also appear as: Soy Isoflavones, Genistein, Daidzein.
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