It will be the first to directly compare the impact of the herbals with a standard hormone treatment.
The results could have a significant outcome on the advice given to women seeking alternatives to HRT, which has recently been found to increase risk of stroke and, in some forms, breast cancer.
Recent studies in Europe suggest that both black cohosh and red clover may help reduce hot flashes brought on by the menopause. Both herbs contain components that act in a similar way to female hormones in the body but there is a lack of consistent evidence to support their benefits in major trials.
Use of herbal supplements to treat menopause symptoms has however surged following the findings of three large-scale trials on HRT linking the treatment to increased risk of breast cancer, heart attacks, stroke, dementia and most recently, age-related hearing loss.
While some scientists have sought to keep the risk in perspective, saying that it remains very low, many consumers will be keen to find alternatives. Just this week researchers said they had halted the latest study on HRT, testing Wyeth's Premarin which contains 0.625mg of oestrogen only, as it increased the risk of stroke from 21 per 10,000 women each year to 29 in 10,000.
The herbals research, taking place at Northwestern Memorial Hospital, in collaboration with researchers at the UIC/NIH Center for Botanical Dietary Supplements and Northwestern University, will determine the role of botanicals in the management of menopause over one year. It will also test their ability to relieve additional menopausal symptoms, such as insomnia, mood disturbances and sexual problems.
"Many women already use these products for the relief of menopausal symptoms; however, studies have not yet been conducted to show these botanicals should replace hormone replacement therapy (HRT) as the first line of treatment for the short-term relief of hot flashes," said Dr Cate Stika, chief of the division of obstetrics and gynecology, Northwestern Memorial Hospital.
"This study is particularly important in light of the recent confusion surrounding the use of HRT. Many women are asking about alternatives and we need to be able to provide a solid, evidence-based response," she added.
She added that there are a variety of herbal formulations available on the market but little data to determine if they are truly effective or what effect they have on the body, especially with long-term use.
The vast majority of women (about 75 per cent) will experience hot flashes during menopause and may exhibit other problems such as depression, mood swings, sleep disorders, vaginal dryness and joint pain.
"Hormone therapy is still a valid choice for women with significant hot flashes because it is proven to work. The purpose of this study is to determine if these botanicals are also effective under a rigorous scientific protocol. The majority of previous studies are only short-term," added the researcher.
The team, being sponsored by the National Institutes of Health and the National Center for Complementary and Alternative Medicine, will monitor health effects and quality of life over approximately 14 study visits. Lipid levels, bone turnover and effects on the endometrial tissue in the uterus will be assessed, as well as any long-term effects and possible risks associated with use of these botanicals.