- Cow clover
- Wild clover
- Purple clover beebread
- Cow grass
- Meadow clover
- Purple clover
For Patients & Caregivers
Red clover may help reduce some menopausal symptoms.
Red clover contains compounds known as isoflavones (also found in soy) that show estrogenic activity in laboratory experiments. The isoflavones in red clover include biochanin, daidzein, formononetin and genistein. However, when used in the body, the effects of red clover isoflavones are less clear. They seem to have estrogenic activity, but so far have not been found to relieve menopausal symptoms or cause the endometrium to grow. A study of menopausal women found that red clover extract improved the elasticity of major arteries. Loss of elasticity may occur through menopause. This can contribute to increases in blood pressure that cause the heart to work harder. However, it is not known if red clover can protect against the development of heart disease, and this will require more clinical trials.
In laboratory experiments, red clover extract can stimulate the production of estrogen receptor-positive breast cancer cells, indicating that this herb may not be helpful for women with estrogen-sensitive cancers. Red clover was also shown to stop the growth of normal prostate cells and increase resistance of prostate cancer cells to high-dose radiation in lab experiments.
Patients should avoid the use of red clover during radiotherapy for prostate cancer, or if you have estrogen receptor-positive cancers.
- To relieve chest congestion
No scientific evidence supports this use.
- To relieve the symptoms of menopause
The red clover product Promensil® was no better than placebo in treating menopausal symptoms.
- To prevent heart disease in post-menopausal women
A few clinical trials have looked at the effects of red clover on development of risk factors for heart disease in postmenopausal women, with no strong evidence that it helps. Most studies found that red clover had no effect on blood cholesterol or triglyceride levels. One clinical trial found that red clover increased the elasticity of major arteries, which may help prevent a gradual rise in blood pressure that can contribute to heart disease.
- To stop muscle spasms
No scientific evidence supports this use.
- You are taking warfarin or other blood thinners: Red clover can increase the risk of bleeding.
- You have a hormone-sensitive disease such as estrogen receptor-positive breast cancer, ovarian cancer, endometriosis, or others: Red clover may have estrogenic activity and should be avoided or used cautiously by patients with these estrogen-sensitive diseases.
- You are taking methotrexate: Red clover may cause toxic effects, including severe vomiting and pain in the upper abdomen.
For Healthcare Professionals
Red clover is a perennial herb traditionally used to treat skin disorders such as psoriasis and eczema, whooping cough, and mastitis. It contains compounds known as isoflavones that act as phytoestrogens. A red clover isoflavone extract is widely promoted as a dietary supplement to relieve menopausal symptoms.
In vitro studies indicate that red clover extract acts as an estrogen agonist and stimulates proliferation of ER-positive breast cancer cells (1). However, Biochinin A, a red clover isoflavone, was shown to inhibit aromatase activity and expression (2), thereby conferring a protective effect. In other studies, isoflavone-enriched extracts of red clover demonstrated neuroprotective effects in human cortical neurons (3) (4) and reduced skin aging in mice by increasing the amount of collagen (5).
Clinical data show that red clover isoflavone supplementation improves menopausal symptoms compared to placebo (6) (7) (8). However, conclusions from systematic reviews are conflicting: one suggests marginal benefit whereas the second found no evidence of effectiveness (9) (10). In postmenopausal women, red clover supplements were shown to alleviate vasomotor and menopausal symptoms (18). Red clover isoflavones may also improve bone loss but more data are needed (11). In a small study, dietary isoflavone intake improved arterial compliance, an index of the elasticity of large arteries, which is an important cardiovascular risk factor (12).
Red clover was shown to inhibit growth of normal prostate cells and increase resistance of prostate cancer cells to high-dose radiation in vitro (15). Patients should avoid use of red clover during radiotherapy for prostate cancer.
Formononetin, a red clover isoflavone, induced apoptosis in human breast cancer cells by activating the Ras-p38 mitogen-activated protein kinase in ER-positive breast cancer cells (23). Biochanin A, another red clover isoflavone had inhibitory effects on the activity and gene expression of aromatase, an enzyme that catalyzes the conversion of androgen to estrogen (2). It also protected dopaminergic neurons against lipopolysaccharide-induced damage via inhibition of microglial activation and generation of pro-inflammatory factors (3). An isoflavone-enriched fraction too showed neuroprotective activity in human cortical neurons, which is thought to be due to antioxidant and estrogenic effects (4).
In a study of rats, red clover isoflavones reduced skin aging induced by estrogen deprivation following ovariectomy (5).
- Case report: Subarachnoid hemorrhage was reported in a 53-year-old woman following use of an herbal supplement containing red clover, dong quai, and Siberian ginseng for hot flashes associated with perimenopause. Her symptoms resolved after discontinuing use of the supplement (16).
Anticoagulants / Antiplatelets: Red clover may increase their effects (20).
Cytochrome P450 enzymes: Red clover can inhibit CYP1A2/2C8/2C9/2C19/2D6 and 3A4, and may interact with substances metabolized by these enzymes (17).
Methotrexate: Red clover has been reported to cause toxicity, resulting in severe vomiting and epigastric pain, when used along with methotrexate injections (19).