News - St Johnís Wort may hold promise against menopausal hot flushes
Hot flushes are the most characteristic and distressing symptom associated with the menopause, and a major cause of reduced quality of life for many menopausal women. Symptoms consist of a sudden rush of heat that typically begins in the chest and may progress to the neck and face, usually in a wave-like sensation. The face may also turn red (flushing) which is often accompanied by sweat. These symptoms are actually an example of your body’s cooling mechanisms in action.
The hypothalamus is the part of your brain responsible for monitoring your real or internal body temperature and keeping it within a specific range. If your temperature increases beyond this range the hypothalamus senses it and brings it back to normal range by activating these cooling mechanisms. Some researchers think that the drop in oestrogen levels during the menopause has a direct effect on the hypothalamus, causing disturbances in its temperature controlling machinery and also narrowing the temperature range at which the body does not find it necessary to actively adjust the internal body temperature. As a result, much smaller increases in body temperature trigger the body’s cooling mechanisms resulting in a hot flush.
The results of a small clinical study suggest that St John’s wort, although best known as a mild herbal antidepressant, may also help to ease menopausal hot flushes. Marjan Khajehei at Shiraz University of Medical Sciences in Iran, and colleagues randomly assigned 100 women, with moderate to severe hot flushes, to take drops containing either St John’s wort extract or a placebo for eight weeks. The results showed that the group taking the St John’s wort experienced a greater reduction in daily hot flushes, declining from four a day to less than two a day by the eighth week. In contrast, the placebo group experienced an average of 2.6 hot flushes per day by the eighth week. The duration and severity of hot flushes were also reduced in the group taking the St John’s wort extract. St John’s wort contains phytoestrogens, compounds with weak oestrogen-like activity derived from plants, which may help to explain the benefits seen in this study.
While the results of this study are encouraging, the research team needs to do more work to confirm that the herb eases hot flushes and to determine whether phytoestrogens are responsible for this effect.
Abdali K, Khajehei M, and Tabatabaee HR. Effect of St John's wort on severity, frequency, and duration of hot flashes in premenopausal, perimenopausal and postmenopausal women: a randomized, double-blind, placebo-controlled study. Menopause 2010; 17:326-31.