Study Breakdown · Women’s Midlife
How S-Equol Is Formed: What a 2005 Study Established
Direct answer
Certain human gut bacteria can convert daidzein, a soy isoflavone, into S-equol. In 2005, Setchell and colleagues separated the two mirror-image forms of equol and identified the S form in the human samples and intestinal cultures they examined.
Key points
- Daidzein is a starting molecule. S-equol is a metabolite formed through bacterial conversion.
- The researchers used laboratory methods to distinguish S-equol from R-equol.
- The study addressed molecular identity, formation and related laboratory and pharmacokinetic questions. It did not test relief of menopausal symptoms.
Scientific background
S-equol and R-equol are enantiomers, two forms with the same chemical composition arranged as mirror images. Detecting equol alone leaves its form unresolved. The 2005 study asked which form was present in human samples and which form cultured intestinal bacteria produced from daidzein.
What the research examined
The researchers used chiral chromatography and mass spectrometry to distinguish the forms in human urine and plasma. They also incubated cultured human intestinal bacteria with daidzein to examine formation outside the body. Separate experiments measured estrogen receptor binding and examined what happened after single oral doses of the two forms in three healthy adults.
What the study found
In the samples and cultures tested, the bacterially formed equol was S-equol. The binding experiments also found that S-equol had a relatively high affinity for estrogen receptor beta under the laboratory conditions. The formation and binding experiments answer distinct questions about the molecule.
What the study does not establish
These results do not establish how common equol production is in a population, whether an individual will produce it, or whether eating soy or taking an S-equol supplement will relieve symptoms. Receptor binding does not establish a clinical outcome.
Limitations
The bacterial incubations were laboratory experiments. The human pharmacokinetic component involved three healthy adults and single doses, so it provides limited information about exposure and cannot establish effects of repeated use or effects in a menopausal population.
Evidence context
Ingredient Evidence — This study helps explain S-equol’s identity and biological formation. Finished-product Evidence — This study was not conducted on the finished DR.MORGAN product.
Relationship to DR.MORGAN
S-EQUOL PLUS provides already-formed S-equol. The biological pathway discussed here describes formation from daidzein in the gut. See Health Canada’s record for NPN 80143622 for this product’s authorized use and directions.
References
- Setchell KDR, Clerici C, Lephart ED, et al. S-equol, a potent ligand for estrogen receptor beta, is the exclusive enantiomeric form of the soy isoflavone metabolite produced by human intestinal bacterial flora. American Journal of Clinical Nutrition. 2005;81(5):1072–1079. DOI and original paper · PubMed 15883431.
- Health Canada. Licensed Natural Health Products Database. S-EQUOL PLUS / EquoPro, NPN 80143622.