ABSTRACT
Red clover (RC) is a herbaceous perennial plant that inhabits temperate and subtropical areas throughout the world. Native Americans traditionally valued RC for treatment of external skin problems and lung, nervous, and reproductive system ailments. Herbalists have employed it as a blood cleanser, expectorant, alterative, and sedative. With the recognition of its high content of mildly estrogenic isoflavones, the plant has gained popularity as a treatment for menopausal symptoms. Clinical evidence is presently lacking to support the efficacy of semipurified RC isoflavone extracts for alleviation of vasomotor and prostate cancer=benign prostatic hyperplasia (BPH) symptoms. Limited evidence suggests possible efficacy in prevention of osteoporosis and improvement of arterial compliance, a risk factor for atherosclerosis. Current RC isoflavone products do not contain a protein fraction, which precludes analogous comparison with isoflavone studies utilizing dietary soy [Glycine max (L.) Merr.] or soy protein isolates (SPIs) for various clinical outcomes. RC isoflavone extract preparations may also differ from soy isoflavone extracts in content of minor chemicals, many of which have not yet been identified, quantified, or tested for biological activity. The need for long-term studies of RC isoflavone supplements is great, as placebo effects, especially for menopausal symptoms, may persist several weeks. Also, thyroid disease and cancer patients may face a potential, yet undefined, risk from long-term exposure to isoflavones and other compounds in RC.
