DOES IT WORK? Dónal O'Mathúnainvestigates Dong quai and menstrual symptoms
DONG QUAI has been used for centuries in traditional Chinese medicine for a variety of gynaecological problems, including relief of premenstrual syndrome (PMS).
After concerns were raised a few years ago about potential adverse effects from hormone replacement therapy, dong quai became popular as one of several herbal remedies recommended for menopausal symptoms.
Many of these symptoms can be traced to the way levels of oestrogen - the female hormone - drop with menopause. Claims have been made that dong quai is a natural alternative to oestrogen.
In traditional Chinese medicine, more than 500 different herbs are used for menstrual health, but dong quai is said to be the most commonly used herb. In treating women, dong quai is combined with other herbs, but it has become popular in the West as a single-herb product. The remedy is made from a dried extract of the plant's roots.
Evidence from studies
Studies with animals have shown that dong quai contains compounds that affect the uterus. However, the effects vary considerably depending on how the compounds were obtained from the plant material.
Most herbal remedies are made from water or alcohol extracts. In animals, these extracts were found to stimulate the uterus suggesting they have weak oestrogen-like activity.
A volatile oil can also be extracted from the plant roots, giving a water insoluble extract. In animals, this has been found to have anti-oestrogenic activity.
Such conflicting results make it difficult to predict how products might affect women, especially when the precise procedures used to make the remedies are usually not stated on labels.
Only one clinical trial using dong quai for postmenopausal symptoms has been published. Seventy one women with bothersome night sweats or hot flushes took either dong quai or placebo for 24 weeks.
Both the women and the researchers were unaware of who received which treatment. No significant changes were found when the women were given gynaecological examinations, indicating that the herb did not have any oestrogen-like actions.
The number and intensity of hot flushes and night sweats decreased equally in both the dong quai and placebo groups. The most likely explanation for these changes is that dong quai was working via the placebo effect.
One other controlled study evaluated dong quai as part of a multi-herb product. While the herbal remedy reduced the menstrual problems more than placebo, which of the herbs led to the changes could not be determined. In addition, the women were allowed to use conventional medications as needed during the study.
Problematic aspects
Very few adverse effects have been reported with dong quai. However, laboratory studies have produced some worrisome results. One showed that a dong quai water extract mildly stimulated the growth of breast cancer cells.
Dong quai contains several compounds which can cause the skin to become sensitive to sunlight, resulting in dermatitis. Extracts contain several compounds known to interfere with blood clotting.
Therefore, anyone taking blood thinners, such as warfarin or aspirin, could be at increased risk of bleeding if they take dong quai. In traditional Chinese medicine, dong quai is considered unsafe to take during pregnancy, although there are no studies to explain why this might be the case.
Although the volatile oil from dong quai is usually not used in herbal remedies, it has been shown to contain small amounts of chemicals known to be carcinogenic.
Recommendations
Dong quai is one of those herbal remedies with a long history of traditional use, but with no controlled clinical studies to support that use. A few animal studies suggest it could affect women's reproductive systems, but the effects are inconsistent and contradictory.
There is also some evidence that using dong quai carries a number of risks.
However small those risks might be, given the lack of evidence for any benefit, there is no good reason to recommend using dong quai.
• Dónal OMathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University