Red Clover Overview

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.

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 hot flash symptoms as compared to placebo. ¹ Benefits were also seen in a 90-day study of 60 post-menopausal women given placebo or 80 mg of red clover isoflavones. ² However, a much larger study (252 participants) failed to find benefit with 82 or 57 mg of red clover isoflavones daily. ³ 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. ⁴ 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. ⁵

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.

1. van de Weijer PH, Barentsen R. Isoflavones from red clover (Promensil) significantly reduce menopausal hot flush symptoms compared with placebo. Maturitas. 42(3):187-93.
2. Tice JA, Ettinger B, Ensrud K, Wallace R, Blackwell T, Cummings SR. Phytoestrogen supplements for the treatment of hot flashes: the Isoflavone Clover Extract (ICE) Study: a randomized controlled trial. JAMA. 290(2):207-14.
3. Tice JA, Ettinger B, Ensrud K, Wallace R, Blackwell T, Cummings SR. Phytoestrogen supplements for the treatment of hot flashes: the Isoflavone Clover Extract (ICE) Study: a randomized controlled trial. JAMA. 290(2):207-14.
4. Baber RJ, Templeman C, Morton T, Kelly GE, West L. Randomized placebo-controlled trial of an isoflavone supplement and menopausal symptoms in women. Climacteric. 2(2):85-92.
5. Knight DC, Howes JB, Eden JA. The effect of Promensil, an isoflavone extract, on menopausal symptoms. Climacteric. 2(2):79-84.