Herbs & Supplements:
Red Clover
Trifolium pratense
Principal Proposed Uses
•
Menopausal Symptoms
Other Proposed Uses
•
Cyclic Mastalgia, Acne, Eczema, Psoriasis, Cancer
Red clover has been cultivated since ancient times, primarily to provide a favorite grazing food for animals. But, like many other herbs, red clover was also a valued medicine. Although it has been used for many purposes worldwide, the one condition most consistently associated with red clover is cancer. Chinese physicians and Russian folk healers also used it to treat respiratory problems.
In the nineteenth century, red clover became popular among herbalists as an "alterative" or "blood purifier." This medical term, long since defunct, refers to an ancient belief that toxins in the blood are the root cause of many illnesses. Cancer, eczema, and the eruptions of venereal disease were all seen as manifestations of toxic buildup.
Red clover was considered one of the best herbs to "purify" the blood. For this reason, it is included in many of the famous treatments for cancer, including the Hoxsey cancer cure and Jason Winter's cancer-cure tea.
Recently, special red clover extracts high in substances called isoflavones have arrived on the market.
What Is Red Clover Used for Today?
Recently, red clover products have been marketed as a treatment for menopausal symptoms. They supply four major isoflavones: genistein and daidzen, also found in soy, as well as formononetin and biochanin. These isoflavones produce effects somewhat similar to estrogen, and for this reason they are called phytoestrogens (“phyto” indicates a plant source).
Although evidence is incomplete and somewhat inconsistent, adequate doses of red clover isoflavones may be helpful for menopausal hot flashes.1,2,7
Red clover isoflavones were not found effective for reducing cholesterol levels in a 12-week, double-blind study of 66 women.3
A small and poorly reported, double-blind, placebo-controlled study provides weak evidence that red clover isoflavones might be helpful for cyclic mastalgia.6
There is no evidence that red clover can help cancer. However, its usage in many parts of the world as a traditional cancer remedy has prompted scientists to take a close look at the herb. It turns out that the isoflavones in red clover may possess antitumor activity.4,5 However, such preliminary research does not prove that red clover can treat cancer.
Red clover is sometimes recommended for the treatment of acne, eczema, psoriasis, and other skin diseases.
What is the Scientific Evidence for Red Clover
Menopausal Hot Flashes
In a 12 week double-blind, placebo controlled trial of 30 post-menopausal women, use of red clover isoflavones at a dose of 80mg daily significantly reduced hot flash symptoms as compared to placebo.7
Two other studies failed to find benefit. One, a 28-week, double-blind, placebo-controlled crossover study of 51 postmenopausal women, found no reduction in hot flashes among those given 40 mg of red clover isoflavones daily.1 The negative results of this trial suggest that perhaps a higher dosage is necessary.
No benefits were seen in another double-blind, placebo-controlled trial, which involved 37 women given isoflavones from red clover at a dose of either 40 or 160 mg daily; however, this three-way study may have involved too few women to identify a treatment effect.2
Dosage
A typical dosage of red clover extract provides 40 to 160 mg of isoflavones daily. In the positive study described above, 80 mg daily were sufficient to reduce menopausal hot flashes.
Safety Issues
Red clover is on the FDA's GRAS (generally recognized as safe) list, and is included in many beverage teas. However, detailed safety studies have not been performed.
Because of its blood-thinning and estrogen-like constituents, red clover should not be used by pregnant or nursing women, or women who have had breast or uterine cancer. Safety in young children or those with severe liver or kidney disease has also not been established.
Based on their constituents, red clover extracts may conceivably interfere with hormone treatments and anticoagulant drugs.
For other potential risks due to the isoflavones in red clover (especially in concentrated isoflavone-rich extracts of red clover), see the full article on isoflavones.
Interactions You Should Know About
If you are taking hormones or blood-thinning drugs—such as Coumadin (warfarin), heparin, Plavix (clopidogrel), Ticlid (ticlopidine), Trental (pentoxifylline), or even aspirin—red clover should be used only under a physician's supervision.
View References
Last reviewed September 2002 by Medical Review Board
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