By Margarita Nahapetyan
There is little scientific evidence that herbal remedies can relieve symptoms of menopause, suggests a new independent review, and some of them may even have serious side effects and be potentially dangerous if interacted with other treatments.
According to the review, for the past 7 years a large number of women have turned to herbal remedies to relieve menopause symptoms. Herbal treatments may be taken to ease hot flashes, night sweats, sleeplessness, mood swings, tiredness and loss of libido that may occur caused by the sharp fall in estrogen levels. It is estimated that 30 to 70 percent of women in industrialized countries experience vasomotor symptoms during menopause, which can last anywhere from 4 to 12 years.
The study, titled 'Herbal medicines for menopausal symptoms,' was published in the latest issue of the Drug and Therapeutics Bulletin, by the British Medical Association. In their study, the researchers conducted 26 clinical trials on the safety and effectiveness of herbal medicines, often taken for menopausal symptoms, such as black cohosh (Actaea racemosa), wild yam extract, chaste tree, sage leaf, red clover extract (Trifolium pratense), dong quai (Angelica sinensis), ginseng (Panax ginseng), evening primrose oil (Oenothera biennis), hops and kava kava. Black cohosh is the root of a native North American plant, red clover contains plant versions of estrogen, Dong quai is a root used in Chinese medicine, evening primrose oil is extracted from the seeds of the wild flower, and ginseng root has been used in Asian medicine for a millennia.
The UK Medicines and Healthcare products Regulatory Agency (MHRA) has given a Traditional Herbal Registration to Menoherb, which contains black cohosh, under a scheme designed to boost the safety of herbal products on sale. But clinical trial data on black cohosh are "equivocal," the article said, with some studies suggesting that the remedy works well, while others are of a different opinion, suggesting that it does not relieve symptoms effectively. Several placebo-controlled trials failed to find significant benefits from black cohosh for vasomotor symptoms or vaginal dryness, but the 3 other trials have suggested benefits of the herb. Black cohosh also may be associated with liver toxicity.
Amongst the other remedies commonly used there is "no convincing evidence" that red clover extract is effective at all. Red clover contains phytoestrogens, and a meta-analysis of five trials of red clover extract found no difference between the remedy and placebo for the frequency of hot flashes. Very little evidence was found that dong quai, evening primrose oil, wild yam, chaste tree, hops, or sage have benefits in menopause treatment. Dong quai has the effect as that of warfarin and may be linked to photosensitivity. Evening primrose oil is a source of linoleic acid and gamma linolenic acid is assumed to increase the risk of seizures when given with medicine that can cause seizures. Ginseng is considered to be well-tolerated, but has been linked to headaches and gastrointestinal problems, according to the review.
"Such products are often assumed to be 'safe' on the grounds that they are 'natural,' and many patients do not tell their doctors that they are taking herbs," said journal editor and review author Ike Iheanacho. "In reality, however, herbal medicines have pharmacological actions, and so can cause unwanted effects and have potentially dangerous interactions with other medicines (both herbal and conventional)." Iheanacho suggests that doctors need to make sure if their patients are taking herbal remedies in order to have an idea about the potential risks and benefits.
Few years ago, some studies suggested that hormone replacement therapy, which replenishes hormone levels and makes menopause symptoms more tolerable, may increase the risk of breast and ovarian cancers and also lead to heart attacks, strokes and blood clots. The use of herbal medicines to treat menopausal symptoms is widespread, but there is a lack of licensed products available on the market. Much of the published studies were not rigorous enough to establish a real value of the products and to assess their safety and effectiveness. Many studies included just few participants, the trials were too short to provide precise details and give answers to questions posed. It is possible that different ways of procession of the same herb made it difficult to compare trial results, the review concluded. "There are a fair number of studies but when you drill it down to the ones that can give you useful information, those are in the minority," Iheanacho said.
Jenny Jones of the Herb Society said: "A lack of evidence does not necessarily mean a lack of effect. Not much clinical research has been done and we do need more. But there is not enough of the funding to do this type of work.
MHRA is implementing the Traditional Herbal Medicinal Products Directive, which will start operating in 2011. This will mean that all over-the-counter herbal remedies will have to conform to the Traditional Herbal Medicines Registration Scheme, and meet safety and quality standards.