Supplements · Femcare actives
Soy Isoflavones & Equol
大豆イソフラボン・エクオール (Daizu isofurabon / Ekuōru)
Also known as: Daidzein, Genistein, Glycitein (aglycone isoflavones), Daidzin, Genistin, Glycitin (glycoside isoflavones), S-Equol, Lactic-acid-fermented Equol
At a glance
| Category | Supplements |
|---|---|
| Japanese labeling name | ダイズイソフラボン / エクオール |
| Common Japanese notations | 大豆イソフラボン, エクオール, ダイズイソフラボン, S-エクオール |
| Origin | Plant-derived (Glycine max soybean) and fermented (S-Equol produced by Lactococcus 20-92 from soy isoflavones) |
| Typical functions | Support for women's wellness through midlife / 'yuragi-ki' (transitional years), Bone-maintenance support (FFC-accepted endpoint), Skin elasticity and quality support, Cardiovascular and metabolic support |
| Regulatory status in Japan | Soy isoflavone preparations have legacy Tokuho approvals (e.g. for bone support) and several Foods with Function Claims notifications. S-Equol is sold as a dietary supplement ingredient; Otsuka Pharmaceutical's 'Equelle' (2014) was the world's first commercial lactic-acid-fermented S-Equol product. |
Soy isoflavones are a family of phytoestrogen compounds (daidzein, genistein, glycitein and their glycosides) found in soybeans and soy-based foods. S-Equol, a downstream metabolite produced from daidzein by gut bacteria, is the bioactive form responsible for many of the observed health endpoints — and only an estimated 50% of Japanese women (versus around 30% of Western women) naturally produce equol from dietary soy. Otsuka Pharmaceutical's 2014 launch of Equelle® was the world's first commercial lactic-acid-fermented S-Equol supplement, allowing consumers without natural equol-producing gut bacteria to obtain the molecule directly.
Classification
Tags below link to other ingredients sharing the same attribute, so you can pivot from one ingredient to its peers.
Product applications
Regulatory tags
Used in (typical product categories)
Finished-product categories that commonly include this ingredient in Japanese-market formulations.
- Femcare and 'yuragi-ki' supplements
- Bone-support FFC supplements
- Beauty drinks and jelly formats
- Tokuho-approved soy isoflavone food products (legacy)
What it is
Soy isoflavones occur in soybeans (Glycine max) primarily as glycosides (daidzin, genistin, glycitin), which are converted to their bioactive aglycone forms (daidzein, genistein, glycitein) by intestinal beta-glucosidases or by fermentation. Aglycone-form ingredients (such as koji-fermented soy isoflavones) are commonly used in Japanese supplements because they are absorbed more rapidly and consistently than the glycoside forms.
S-Equol is a chiral isoflavone metabolite derived from daidzein via reduction by specific gut bacteria. In the human population, only a subset of individuals carries equol-producing gut microbiota; estimates indicate around 50% of Japanese versus around 30% of Western women are natural equol producers. To address this gap, Otsuka Pharmaceutical isolated 'Lactococcus 20-92', a lactic-acid bacterium capable of producing S-Equol from soy daidzein, and commercialised the resulting fermented S-Equol in the Equelle® product (2014).
Commercial supplement preparations include standardised soy isoflavone aglycone powders (e.g. Fuji-Flavone, AglyMax) and fermented S-Equol concentrates (Equelle®). Cosmetic preparations of soy isoflavone extract are also used, but the entry's primary positioning is as a supplement / functional food active.
Typical uses in Japanese products
In Japan, soy isoflavone and equol products are most strongly associated with the 'yuragi-ki' (ゆらぎ期 — the menopausal transition years) wellness category. Tablet, soft-gel, and jelly supplements are positioned around midlife wellness, hormonal balance support, and skin quality. Daily dosing is set per FFC notification or general supplement design and should respect the Japanese Food Safety Commission's recommended upper limit on aglycone-form isoflavone intake.
Bone-maintenance positioning is supported by legacy Tokuho approvals and current Foods with Function Claims notifications. Soy isoflavones are also used in beauty drinks, fortified bars, and women's wellness functional foods, often paired with calcium, vitamin D, collagen peptide, or placenta extract depending on the wellness narrative.
Regulatory classification in Japan
Soy isoflavone preparations have legacy Tokuho (特定保健用食品) approvals — notably for bone-support positioning — granted by the Consumer Affairs Agency. Several Foods with Function Claims (機能性表示食品) notifications using soy isoflavones for bone maintenance and related endpoints have also been accepted; brands wishing to make similar claims must submit their own FFC notification with appropriate supporting evidence.
The Food Safety Commission of Japan has issued guidance on a recommended upper daily intake for isoflavone aglycones from supplement use (separate from intake via traditional soy foods). Brands formulating soy isoflavone supplements for the Japanese market should design daily dosing in line with this guidance.
S-Equol as a fermented dietary supplement ingredient is sold in Japan under DSHEA-equivalent dietary supplement framing; Otsuka's Equelle® is the reference commercial product. Brands considering similar fermented S-Equol positioning should review the regulatory and IP landscape carefully — including Otsuka's Lactococcus 20-92 portfolio.
Regulatory classification in other markets
| EU | Isolated soy isoflavone preparations are subject to the Novel Food framework and to EFSA opinions on safety; specific health claims are tightly regulated under the EU health claims register. S-Equol supplement positioning should be reviewed against current EFSA guidance before launch. |
|---|---|
| USA | Soy isoflavone and S-Equol products are sold as dietary supplements under DSHEA. FDA-notified structure / function claims are available; specific health claims (e.g. heart health) are tightly regulated and require an authorised claim or qualified-claim review. |
| China | Soy isoflavone health food products are subject to NMPA / SAMR health-food review; specific functions must align with the approved health-food claims list. Verify supplier documentation and any required NMPA filings before launch. |
| Korea | Soy isoflavone is recognised by the MFDS as a health-functional food ingredient under specific approved claims (e.g. bone health for postmenopausal women). S-Equol products require their own MFDS health-functional-food review. |
Example products
Example finished products will be added after each product's current full ingredient list and (for FFC / Tokuho versions) Consumer Affairs Agency notification or approval has been verified. Because the category is heavily trademarked — particularly around Otsuka's Equelle® and ゆらぎ期® brand portfolio — any example entries will carefully distinguish the general ingredient (soy isoflavones / S-Equol) from trademarked product names.
All brand names and product names referenced anywhere on this site are the property of their respective owners. Example entries are provided for informational purposes only and do not imply endorsement.
Related ingredients
References
- Otsuka Pharmaceutical — Equelle® product information and Lactococcus 20-92 research publications
- Food Safety Commission of Japan — opinion on dietary intake of soy isoflavone aglycones from food supplements
- Japan Consumer Affairs Agency — Tokuho approvals and Foods with Function Claims notification database (soy isoflavone entries)
Last updated: 2026-04-25. Ingredient entries are reviewed at least annually against current regulatory listings.