Red CloverTrifolium pratense
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 "alternative" 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 Jason Winter's cancer-cure tea.
Recently, special red clover extracts high in substances called
What Is Red Clover Used for Today?
Evidence is inconsistent on whether red clover isoflavones are helpful for menopausal hot flashes
Although soy and, possibly, soy isoflavones
There is no evidence that red clover can help treat 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 anti-tumor activity in the test tube.
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 80 mg daily significantly reduced
Two other studies also failed to find benefit. One, a 28-week, double-blind, placebo-controlled crossover study of 51 post-menopausal women, found no reduction in hot flashes among those given 40 mg of red clover isoflavones daily.
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.
Red clover is on the Food and Drug Adminstration's Generally Recognized as Safe (GRAS) 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. A study investigating the safety of red clover in women with a family history of breast cancer found no changes in breast density or thickness of the uterine lining over a three-year period, which is somewhat reassuring. 17 However, the study was much too short to determine red clover's long-term effect on cancer risk. 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 (see the next section for specific drugs).
One double-blind study of post-menopausal women found the use of red clover isoflavones at a dose of 80 mg daily for 90 days resulted in increased levels of testosterone.
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
3. Howes JB, Sullivan D, Lai N, et al. The effects of dietary supplementation with isoflavones from red clover on the lipoprotein profiles of post menopausal women with mild to moderate hypercholesterolaemia. Atherosclerosis. 2000;152:143-147.
4. Cassady JM, Zennie TM, Chae YH, et al. Use of a mammalian cell culture benzo(a)pyrene metabolism assay for the detection of potential anticarcinogens from natural products: inhibition of metabolism by biochanin A, an isoflavone from Trifolium pratense L.Cancer Res. 1988;48:6257-6261.
8. Messina M, Gardner C, Barnes S. Gaining insight into the health effects of soy but a long way still to go: commentary on the fourth International Symposium on the Role of Soy in Preventing and Treating Chronic Disease. J Nutr . 2002;132:547S-551S.
9. Blakesmith SJ, Lyons-Wall PM, George C, et al. Effects of supplementation with purified red clover ( Trifolium pratense ) isoflavones on plasma lipids and insulin resistance in healthy premenopausal women. Br J Nutr . 2003;89:467-475.
12. Howes JB, Tran D, Brillante D, et al. Effects of dietary supplementation with isoflavones from red clover on ambulatory blood pressure and endothelial function in postmenopausal type 2 diabetes. Diabetes Obes Metab . 2003;5:325-332.
15. Hidalgo LA, Chedraui PA, Morocho N et al. The effect of red clover isoflavones on menopausal symptoms, lipids and vaginal cytology in menopausal women: A randomized, double-blind, placebo-controlled study. Gynecol Endocrinol . 2005;21:257-264.
Last reviewed April 2009 by EBSCO CAM Review Board
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