Trial reportThe American journal of clinical nutrition2009
The pharmacokinetic behavior of the soy isoflavone metabolite S-(-)equol and its diastereoisomer R-(+)equol in healthy adults determined by using stable-isotope-labeled tracers.
Trial report in The American journal of clinical nutrition, 2009. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 40 papers.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
40 citing papers in PubMed, 92 citations in OpenAlex.
- Safety and feasibility of estrogen receptor-β targeted phytoSERM formulation for menopausal symptoms: phase 1b/2a randomized clinical trial.Menopause (New York, N.Y.) · 2019Trial
- Acute benefits of the microbial-derived isoflavone metabolite equol on arterial stiffness in men prospectively recruited according to equol producer phenotype: a double-blind randomized controlled trial.The American journal of clinical nutrition · 2016Trial
- Impact of equol-producing capacity and soy-isoflavone profiles of supplements on bone calcium retention in postmenopausal women: a randomized crossover trial.The American journal of clinical nutrition · 2015Trial
- Estrogen receptor and PI3K/Akt signaling pathway involvement in S-(-)equol-induced activation of Nrf2/ARE in endothelial cells.PloS one · 2013Trial
- Equol production changes over time in postmenopausal women.The Journal of nutritional biochemistry · 2012Trial
- Soy isoflavone phase II metabolism differs between rodents and humans: implications for the effect on breast cancer risk.The American journal of clinical nutrition · 2011Trial
- How Gut Microbes Transform Dietary Phytonutrients: Enzymatic Pathways and Human Metabolite Exposure.Molecules (Basel, Switzerland) · 2026Review
- Bioactive Phenolic Compounds in Extra Virgin Olive Oil: Implications for Cardiovascular Health.Food science & nutrition · 2026Review
- Maresin-1 and S-Equol as Emerging Metabolic Biomarkers in Gestational Diabetes-Associated Inflammation.Diagnostics (Basel, Switzerland) · 2025Article
- Polyphenol-Derived Microbiota Metabolites and Cardiovascular Health: A Concise Review of Human Studies.Antioxidants (Basel, Switzerland) · 2024Review
- Interplay between Phytochemicals and the Colonic Microbiota.Nutrients · 2023Review
- Gut Microbiota-Assisted Synthesis, Cellular Interactions and Synergistic Perspectives of Equol as a Potent Anticancer Isoflavone.Pharmaceuticals (Basel, Switzerland) · 2022Review
- Dietary Isoflavone Aglycons from Soy Germ Pasta Improves Reproductive Performance of Aging Hens and Lowers Cholesterol Levels of Egg Yolk.Metabolites · 2022Article
- Use of Physiologically Based Pharmacokinetic Modeling to Predict Human Gut Microbial Conversion of Daidzein to S-Equol.Journal of agricultural and food chemistry · 2022Article
- Recent progress in DNA methyltransferase inhibitors as anticancer agents.Frontiers in pharmacology · 2022Review
- Phytoestrogens (Resveratrol and Equol) for Estrogen-Deficient Skin-Controversies/Misinformation versus Anti-Aging In Vitro and Clinical Evidence via Nutraceutical-Cosmetics.International journal of molecular sciences · 2021Review
- Flavonoid consumption and cardiometabolic health: Potential benefits due to foods, supplements, or biomarkers?The American journal of clinical nutrition · 2021Article
- Structural and Functional Alterations of Gut Microbiota in Males With Hyperuricemia and High Levels of Liver Enzymes.Frontiers in medicine · 2021Article
- Effects of Smoking on Inflammatory Markers in a Healthy Population as AnalyzedFrontiers in cellular and infection microbiology · 2021Article
- The phytoestrogens daidzein and equol inhibit the drug transporter BCRP/ABCG2 in breast cancer cells: potential chemosensitizing effect.European journal of nutrition · 2019Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
5 authors at 1 institution in 1 country.
Funding
Abstract
backgroundThe nonsteroidal estrogen equol occurs as diastereoisomers, S-(-)equol and R-(+)equol, both of which have significant biological actions. S-(-)equol, the naturally occurring enantiomer produced by 20-30% of adults consuming soy foods, has selective affinity for estrogen receptor-beta, whereas both enantiomers modulate androgen action. Little is known about the pharmacokinetics of the diastereoisomers, despite current interest in developing equol as a nutraceutical or pharmaceutical agent.
objectiveThe objective was to compare the pharmacokinetics of S-(-)equol and R-(+)equol by using [13C] stable-isotope-labeled tracers to facilitate the optimization of clinical studies aimed at evaluating the potential of these diastereoisomers in the prevention and treatment of estrogen- and androgen-dependent conditions.
designA randomized, crossover, open-label study in 12 healthy adults (6 men and 6 women) compared the plasma and urinary pharmacokinetics of orally administered enantiomeric pure forms of S-(-)[2-13C]equol, R-(+)[2-13C]equol, and the racemic mixture. Plasma and urinary [13C]R-equol and [13C]S-equol concentrations were measured by tandem mass spectrometry.
resultsPlasma [13C]equol concentration appearance and disappearance curves showed that both enantiomers were rapidly absorbed, attained high circulating concentrations, and had a similar terminal elimination half-life of 7-8 h. The systemic bioavailability and fractional absorption of R-(+)[2-13C]equol were higher than those of S-(-)[2-13C]equol or the racemate. The pharmacokinetics of racemic (+/-)[2-13C]equol were different from those of the individual enantiomers: slower absorption, lower peak plasma concentrations, and lower systemic bioavailability.
conclusionsThe high bioavailability of both diastereoisomers contrasts with previous findings for the soy isoflavones daidzein and genistein, both of which have relatively poor bioavailability, and suggests that low doses of equol taken twice daily may be sufficient to achieve biological effects.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.