Compound Monograph
Coumestrol
Coumestrol is a plant compound (coumestan) that acts as a phytoestrogen, found in red clover and legume sprouts.
Classification
Coumestrol is a coumestan (phytoestrogen), part of the other constituents class. Compounds outside the major chemical classes — nucleosides, simple amines, mixed volatile oils, and as-yet uncategorised constituents.
Where Does It Come From? (4)
Coumestrol is a naturally occurring coumestan (phytoestrogen), found in Red clover, Alfalfa, Soybean and clover sprouts and 1 other source. It is well tolerated orally (low toxicity).
Research & Evidence
Coumestrol is a coumestan, one of the classes of plant phytoestrogens, found in legumes such as red clover and alfalfa and concentrated in some sprouted seeds. It can bind to estrogen receptors and weakly mimic the body’s own estrogen, which is the basis of interest in clover and related plants for menopausal and hormonal support. Most evidence is from laboratory and animal studies.
Monoamine oxidase (MAO) inhibition
Beyond its phytoestrogen activity, coumestrol is a moderately potent and notably MAO-A-selective inhibitor: a full dose-response study reported an IC50 of about 1.99 µM against MAO-A versus roughly 78 µM against MAO-B — around a 40-fold preference for MAO-A — with a competitive mechanism 1Reference 1Phytoestrogen coumestrol selectively inhibits monoamine oxidase-A and amyloid β self-aggregationView study →. See the natural MAO inhibitors guide for how this compares across plants.
Toxicity & Safety
Coumestrol occurs in ordinary foods such as legumes and sprouts and is not regarded as notably toxic at dietary levels. Because it is an estrogen-mimicking compound, concentrated phytoestrogen intake may warrant caution in hormone-sensitive situations, a consideration that applies to the source plants generally rather than to coumestrol specifically.
References
- Seong, S. H., Kim, B. R., Cho, M. L., Kim, T. S., Im, S., Han, S., Jeong, J. W., Jung, H. A., & Choi, J. S. (2022). Phytoestrogen coumestrol selectively inhibits monoamine oxidase-A and amyloid β self-aggregation. Nutrients, 14(18), 3822. https://pubmed.ncbi.nlm.nih.gov/36145197/