Soy Isoflavones for Skin

Soy-derived isoflavones have emerged as a promising natural strategy for improving skin appearance in postmenopausal women. Drawing on their phytoestrogenic properties, these compounds are investigated for their potential to reduce wrinkles, improve skin hydration, and enhance overall skin elasticity. Recent studies have explored different formulations—from soy protein isolates enriched with isoflavones to isolated aglycone forms and combination nutraceuticals—to assess their efficacy in mitigating signs of photoaging and promoting skin rejuvenation.

Protocols Studied in Research

Soy Protein Containing Isoflavones Improves Facial Signs of Photoaging and Skin Hydration [1]

• Protocol: In this 6‑month prospective, randomized, double‑blind controlled trial, 44 postmenopausal women with Fitzpatrick skin types I–III were assigned to receive either a soy protein isolate with added isoflavones (SPII) or a casein protein control. High‑resolution facial photography measured wrinkle severity and pigmentation at 0, 8, 16, and 24 weeks, while skin hydration and sebum production were assessed via biophysical measurements.
• Outcome: The SPII group showed significant reductions in average wrinkle severity by 5.9% at week 16 (p < 0.05) and 7.1% at week 24 (p < 0.0001) compared to baseline and the control group. Facial pigment intensity decreased by 2.5% (p < 0.05) at week 24, and skin hydration increased significantly (39% and 68% on the left and right cheeks, respectively, at 24 weeks).

Oral Intake of Soy Isoflavone Aglycone Improves the Aged Skin of Adult Women [2]

• Protocol: In a double‑blind, placebo‑controlled trial, 26 middle‑aged women in their late 30s to early 40s were randomized to receive either 40 mg/day of soy isoflavone aglycone or placebo for 12 weeks. The primary outcome was the extent of linear and fine wrinkles at the lateral angle of the eyes, measured as the wrinkle area ratio; secondary outcomes included skin microrelief and malar skin elasticity, assessed at 4, 8, and 12 weeks.
• Outcome: The test food group demonstrated a statistically significant improvement in fine wrinkles at week 12 (p < 0.05) and improved malar skin elasticity at week 8 (p < 0.05) compared with the placebo group, with significant intragroup improvements in skin microrelief observed at week 8. No adverse effects were reported.

Wrinkle Reduction in Postmenopausal Women Consuming a Novel Oral Supplement [3]

• Protocol: In a double‑blind, placebo‑controlled, randomized study, postmenopausal women received an oral supplement combining soy isoflavones, lycopene, vitamin C, vitamin E, alongside a fish oil capsule, over a long‑term period. Facial wrinkle depth was assessed using clinical photography, and dermal collagen deposition was evaluated as a marker of skin rejuvenation.
• Outcome: The unique combination of micronutrients resulted in a clinically significant reduction in facial wrinkle depth and was associated with increased deposition of new collagen fibers in the dermis, demonstrating an effective improvement in the appearance of aged skin.

Research Interpretation: Summary and Conclusion

One trial using a soy protein isolate with added isoflavones showed significant reductions in wrinkle severity and pigmentation along with enhanced skin hydration over six months. A second study with soy isoflavone aglycone at 40 mg/day demonstrated improvements in fine wrinkles and skin elasticity in middle-aged women. Moreover, a combined oral supplement featuring soy isoflavones alongside lycopene, vitamins C and E, and fish oil led to reduced wrinkle depth and increased collagen deposition in postmenopausal women.

In simple terms, these findings collectively suggest that soy isoflavones, particularly when appropriately formulated or combined with other nutrients, may offer effective anti-aging benefits for the skin.

Publications

[1] Rizzo J, Min M, Adnan S, Afzal N, Maloh J, Chambers CJ, Fam V, Sivamani RK. Soy Protein Containing Isoflavones Improves Facial Signs of Photoaging and Skin Hydration in Postmenopausal Women: Results of a Prospective Randomized Double-Blind Controlled Trial. Nutrients. 2023 Sep 23;15(19):4113. doi: 10.3390/nu15194113. PMID: 37836398; PMCID: PMC10574417.

[2] Izumi T, Saito M, Obata A, Arii M, Yamaguchi H, Matsuyama A. Oral intake of soy isoflavone aglycone improves the aged skin of adult women. J Nutr Sci Vitaminol (Tokyo). 2007 Feb;53(1):57-62. doi: 10.3177/jnsv.53.57. PMID: 17484381.

[3] Jenkins G, Wainwright LJ, Holland R, Barrett KE, Casey J. Wrinkle reduction in post-menopausal women consuming a novel oral supplement: a double-blind placebo-controlled randomized study. Int J Cosmet Sci. 2014 Feb;36(1):22-31. doi: 10.1111/ics.12087. Epub 2013 Sep 18. PMID: 23927381; PMCID: PMC4265247.