Co-ingestion of soy isoflavones and lactobionic acid improves facial stratum corneum hydration: a randomized, placebo-controlled trial
DOI:
https://doi.org/10.31989/ffhd.v16i3.1904Abstract
Background: Low-dose soy isoflavones (<30 mg/day) alone often show limited effects on skin hydration; co-ingestion with lactobionic acid may enhance absorption and equol bioconversion, potentially improving corneum hydration.
Objective: To evaluate whether co-ingesting soy isoflavones (25 mg aglycone equivalents) with lactobionic acid (250 mg) improves stratum corneum water content compared with isoflavones alone or placebo.
Methods: This randomized, placebo-controlled, parallel-group trial aimed to determine the effects of 12-week consumption of soy isoflavones alone (Iso, 25 mg soy isoflavone aglycone equivalents), soy isoflavones and lactobionic acid (Iso+LAB, 25 mg soy isoflavone (aglycone equivalents) and 250 mg lactobionic acid), or placebo (no soy isoflavone or lactobionic acid) on the stratum corneum water content and urinary isoflavone concentration in 33 healthy adult women.
Results: The stratum corneum water content of the left cheek significantly increased in the Iso+LAB group at 12 weeks, whereas no significant improvement was observed in the Iso group compared with the placebo group. Among equol producers, the Iso+LAB group exhibited significantly higher urine equol levels at 4 weeks compared with the Iso group. Among equol non-producers, the urinary daidzein and genistein concentrations were consistently higher in the Iso+LAB group, although dietary isoflavone intake did not differ among groups.
Conclusions: Co-ingestion of soy isoflavones and lactobionic acid enhanced the stratum corneum water content, likely through improved absorption and metabolism of soy isoflavones, including equol production.
Novelty: This study isolates the specific contribution of lactobionic acid by directly comparing low-dose soy isoflavones alone, soy isoflavones combined with LBA, and placebo, linking skin hydration changes to urinary isoflavone and equol kinetics.
Keywords: soy isoflavone, lactobionic acid, stratum corneum water content, equol, skin, functional food.
Downloads
Published
Issue
Section
License
Copyright (c) 2026 Kaori Homma, Ayaka Kawabata, Saki Yamauchi, Toshinari Maruo, Fumio Nanba, Kenichi Oe, Yuichi Ukawa, Kazuya Mitsuhashi, Toshio Suzuki
This work is licensed under a Creative Commons Attribution 4.0 International License.
Authors retain the copyright of their articles and grant the Functional Food Center (FFC) and its journals the right of first publication under the terms of the Creative Commons Attribution 4.0 International License.
This license permits unrestricted use, distribution, and reproduction in any medium, including commercial use, provided the original author(s) and source are properly credited. Authors may post and share their published work freely, provided that the original publication in this journal is acknowledged.
By submitting to this journal, authors confirm that their manuscripts are original, not under consideration elsewhere, and that they hold the necessary rights to grant this license. The Functional Food Center encourages open scientific exchange and allows derivative and extended works, provided attribution to the original publication is maintained.