In March, the American Herbal Pharmacopoeia (AHP) published a new monograph and therapeutic compendium for red clover (Trifolium pratense, Fabaceae) flowering tops, aerial parts, and dry extracts.1 The long-awaited monograph includes a full suite of identity and quality tests, documents historical uses of the plant, and provides a guidance on harvest and cultivation practices, as well as a full review of clinical and pre-clinical pharmacology and safety data.1
AHP monographs are designed to provide a standard for herb purity and identity, help practitioners make educated choices when prescribing botanicals, and serve as a dossier for companies to ensure safety and substantiate dosage and claims, according to AHP Executive Director Roy Upton.
“The AHP monographs are the only such work in the world that we know of that combine a critical review of the traditional knowledge base coupled with the experience of modern clinicians with a critical review of the scientific literature,” Upton wrote (email, March 24, 2017). “This provides the most comprehensive and critical review of the therapeutic and safety data on the monographed herb anywhere in the world.”
The red clover monograph was initiated and supported by Linnea SA (Riazzino, Switzerland), which makes Promensil, a preparation that contains red clover isoflavones and has been the subject of numerous clinical trials.2
Red clover was considered by Seventh-Day Adventist Church founder Ellen White to be “one of God’s greatest gifts to man.” It has been used historically as an alterative (blood purifier), for infections, boils, skin conditions, vaginal discharge, fever, and inflammation, and to clear the eyes, among many other uses, Upton said. The current primary interest in red clover, he added, is for its use in reducing the severity of symptoms associated with menopause. “Relief of menopause is one of the most sought-after categories in the natural products industry,” he said. “This is especially important considering the higher risks of developing reproductive cancers that exist with conventional hormone replacement therapy.”
A number of studies, however, have called the efficacy of red clover, and isoflavones in general, into question. As a result, one of the important contributions of the monograph and therapeutic compendium, Upton explained, is to provide accurate, fact-based information and to mitigate biased reporting associated with, for example, concerns over the exposure of phytoestrogens in those with estrogen-sensitive cancers.
“Because phytoestrogens act similarly to estrogens, it stands to reason these should be avoided in those with cancer, especially estrogen-sensitive cancers,” Upton wrote. “However, a plethora of scientific data demonstrates no increased risk of cancer when taking isoflavone-containing botanicals like red clover and that there are a number of mechanisms associated with isoflavones that protect and reduce the risk of cancer. This information is especially important for addressing the safety of red clover.”
It typically takes AHP, which relies on the work of numerous volunteers and collaborators, about three years to complete a monograph. “The comprehensive nature of the monographs and the extensive peer review they are subjected to by collaborators throughout the world make it a very time-consuming process,” Upton wrote.
Specifically in the case of the red clover monograph, AHP used 14 different collaborators and an additional 20 reviewers. Contributors included professional historians, international regulators, agricultural researchers in Canada and the United States Pharmacopeia (USP), and reviewers included herbalists and naturopathic physicians in the United States and Australia, ethnobotanists from Canada and Australia, an obstetrics and gynecology specialist from Austria, and researchers from the University of Illinois-Chicago, among others. The team worked to explain why some studies show efficacy and others do not, and to present the data in a clinically relevant context, which requires in-depth familiarity with the literature and the pharmacological and physiological principles involved. Upton added, “the analytical methodology provided courtesy of USP was under revision, and we thought it best to harmonize with USP than to offer an alternative method.” It is typical for AHP to harmonize with European Pharma (EP) or the USP on analytical methods, with a preference for EP because its standard is more reasonable and encompassing, Upton noted (email, April, 12, 2017). In this case, the harmonization did cause a delay in the monograph because USP methods were under revision, and AHP had to re-verify that the methods worked as recorded.
The monograph and therapeutic compendium for red clover is available through AHP’s website at www.herbal-ahp.org. PDFs are available for $39.95, and printed four-color versions can be purchased for $44.95.
- AHP releases standards of identity, analysis, and quality and therapeutic compendium for red clover and red clover extracts. [press release]. Scotts Valley, CA: American Herbal Pharmacopoeia; March 21, 2017. Available at: www.herbal-ahp.org/documents/press_releases./Red%20CloverPRESS%20RELEASE%20for%20Immediate%20Distribution.pdf. Accessed March 23, 2017.
- Novogen Consumer Healthcare. Promensil: A clinical summary. Virtual Medical Center website. Available at: www.myvmc.com/uploads/VMC/DrugImages/Promensil/Promensil-Clinical-Summary-Au.pdf.