Red clover's therapeutic uses

Definition: Natural plant product used to treat specific health conditions.

Principal proposed use: Menopausal symptoms

Other proposed uses: Acne, cyclic mastalgia, eczema, enhancement of mental function, high blood pressure, high cholesterol, osteoporosis, psoriasis

Overview

Red clover has been cultivated since ancient times, primarily to provide a favorite grazing food for animals. Like many other herbs, however, 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 have 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 Winters’s cancer-cure tea.

Special red clover extracts high in substances called isoflavones have arrived on the market. These isoflavones produce effects in the body somewhat similar to those of estrogen, and for this reason, they are called phytoestrogens (“phyto” indicates a plant source). The major isoflavones in red clover include genistein and daidzen, also found in soy, as well as formononetin and biochanin.

Therapeutic Dosages

A typical dosage of red clover extract provides 40 to 160 milligrams (mg) of isoflavones daily. Some evidence suggests that eighty mg daily is a sufficient dosage to reduce menopausal hot flashes.

Therapeutic Uses

Evidence is inconsistent regarding whether red clover isoflavones are helpful for menopausal hot flashes. A small and poorly reported double-blind, placebo-controlled study provides weak evidence that red clover isoflavones might be helpful for cyclic mastalgia.

Although soy and, possibly, soy isoflavones have been found to reduce cholesterol levels, two trials enrolling a total of more than one hundred women failed to find red clover isoflavones helpful for this purpose. However, in a double-blind, placebo-controlled comparative study of eighty people (both men and women), a red clover extract modified to be rich in biochanin did reduce LDL (bad) cholesterol, while one enriched in formononetin did not.

One very small double-blind study found hints that red clover isoflavones might slightly improve blood pressure in postmenopausal women with diabetes. Preliminary evidence suggests that red clover isoflavones may help prevent or treat osteoporosis. In a six-month, double-blind study, use of red clover isoflavones failed to enhance or harm mental function.

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 antitumor activity in the test tube. 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.

Scientific Evidence

Menopausal hot flashes. In a twelve-week double-blind, placebo-controlled trial of thirty postmenopausal women, use of red clover isoflavones at a dose of eighty mg daily significantly reduced hot flash symptoms compared with placebo. Benefits were also seen in a ninety-day study of sixty postmenopausal women given placebo or eighty mg of red clover isoflavones. However, a much larger study (252 participants) failed to find benefit with eighty-two or fifty-seven mg of red clover isoflavones daily.

Two other studies also failed to find benefit. One, a twenty-eight-week double-blind, placebo-controlled crossover study of fifty-one postmenopausal women, found no reduction in hot flashes among those given forty mg of red clover isoflavones daily. No benefits were seen in another double-blind, placebo-controlled trial that involved thirty-seven women given isoflavones from red clover at a dose of either 40 or 160 mg daily. Contrary to these results, a study in 2021 found positive results for the use of red clover in postmenopausal women.

Safety Issues

Red clover is on the US Food and Drug Administration’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 by 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. However, the study was much too short to determine red clover’s long-term effect on cancer risk. Safety in young children and in 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. One double-blind study of postmenopausal women found that the use of red clover isoflavones at a dose of eighty mg daily for ninety days resulted in increased levels of testosterone. The potential significance of this is unclear. The same study found that red clover isoflavones reduced the thickness of the uterine lining, a finding that suggests low possibility of increasing the risk of endometrial cancer.

Important Interactions

Persons who are taking hormones or blood-thinning drugs—such as warfarin (Coumadin), heparin, clopidogrel (Plavix), ticlopidine (Ticlid), pentoxifylline (Trental), or even aspirin—should not use red clover unless they are under a physician’s supervision.

Bibliography

Atkinson, C., et al. “The Effects of Phytoestrogen Isoflavones on Bone Density in Women.” American Journal of Clinical Nutrition, vol. 79, 2004, pp. 326-333.

Hidalgo, L. A., et al. “The Effect of Red Clover Isoflavones on Menopausal Symptoms, Lipids and Vaginal Cytology in Menopausal Women.” Gynecological Endocrinology, vol. 21, 2005, pp. 257-264.

Howes, J. B., K. Bray, et al. “The Effects of Dietary Supplementation with Isoflavones from Red Clover on Cognitive Function in Postmenopausal Women.” Climacteric, vol. 7, 2004, pp. 70-77.

Mohsen, Akbaribazm, et al. “Pharmacological and Therapeutic Properties of the Red Clover (Trifolium pratense L.): An Overview of the New Finding.” Journal of Traditional Chinese Medicine, vol. 41, no. 4, 2021, pp. 642-649. doi:10.19852/j.cnki.jtcm.20210324.001.

"Red Clover." Icahn School of Medicine at Mount Sinai, www.mountsinai.org/health-library/herb/red-clover. Accessed 20 Aug. 2023

"Red Clover." National Center for Complementary and Integrative Health, Oct 2020, www.nccih.nih.gov/health/red-clover. Accessed 20 Aug. 2023.