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 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.

Evidence is inconsistent on whether red clover isoflavones are helpful for menopausal hot flashes,1,2,7,10,15with the largest trial failing to find benefits.10

A small and poorly reported double-blind, placebo-controlled study provides weak evidence that red clover isoflavones might be helpful for cyclic mastalgia.6

Although soy and, possibly, soy isoflavones 8have been found to reduce cholesterol levels, two trials enrolling a total of more than 100 women failed to find red clover isoflavones helpful for this purpose.3,9However, in a double-blind, placebo-controlled comparative study of 80 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.11

One very small double-blind study found hints that red clover isoflavones might slightly improve blood pressurein post-menopausal women with diabetes.12

Preliminary evidence suggests that red clover isoflavones may help prevent or treat osteoporosis.13

In a 6-month, double-blind study, use of red clover isoflavones failed to enhance or harm mental function.14

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.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.