In the first clinical trial of pomegranate seed oil as a treatment for menopausal hot flashes, women taking the supplement twice a day for 12 weeks got no more relief than women taking a placebo pill containing sunflower oil.
Pomegranate seed oil has been marketed as an alternative remedy for menopausal symptoms, because it is rich in plant compounds, called phytoestrogens, that mimic estrogen.
"Like many herbal remedies, there's no clear evidence that it is effective at reducing menopause symptoms," said Dr. Silvina Levis, who specializes in geriatrics at the University of Miami Miller School of Medicine in Florida but was not involved in the study.
Previous research has found that soy supplements and red clover extract, which also contain phytoestrogens, are not effective at reducing menopause symptoms like hot flashes.
As many as 85 per cent of women experience the symptom many times a day -- a sensation of heat, often accompanied by sweating, rapid heartbeat and anxiety -- before, during or after menopause, according to past studies.
In the current study, researchers led by Dr. Leo Auerbach at the Medical University of Vienna, in Austria, followed 81 postmenopausal women between the ages of 45 and 60. All women experienced a minimum of five hot flashes a day and had gone at least 12 months since their final menstrual period.
Each participant kept a daily diary of menopause symptoms and took two 30-milligram capsules of pomegranate seed oil or placebo pills daily for 12 weeks. At the start and the end of the study period, the researchers also tested the women's hormone levels.
At the beginning of the study, women in the treatment group reported having an average of 11.1 hot flashes a day, and women in the placebo group reported 9.9 hot flashes each day, on average.
After 12 weeks, the women taking pomegranate seed oil saw a nearly 39 per cent reduction in hot flashes, to 6.8 per day, while women in the placebo group saw a drop of nearly 26 per cent, to an average of 7.3 hot flashes a day.
Though women in both groups saw a marked decrease in the frequency of their hot flashes, the 13 per cent difference between the effects seen in the two groups was too small to credit pomegranate seed oil with any real benefit.
Because both sets of women saw an improvement, it was likely attributable to the so-called placebo effect in both groups, according to the researchers.
Most placebo-controlled studies of treatments for menopausal symptoms show a pronounced placebo effect, they note. Other researchers have reported that women in the placebo groups of clinical trials had a reduction in the number of hot flashes of up to 60 per cent.
This suggests that menopausal symptoms may be due to psychological as well as hormonal changes, Auerbach told Reuters Health in an email.
The study found no differences between the participants in their hormone levels before and after the 12-week treatment, but the women on pomegranate seed oil did report a statistically significant improvement in sleep quality and related symptoms.
The study, published in the journal Menopause, was funded by German herbal supplement maker, PEKANA, which also supplied the supplements.
Currently, the United States Food and Drug Administration approves only hormone therapy -- medications containing synthetic estrogens -- for the treatment of hot flashes.
Although hormone therapy is highly effective, it carries an increased risk of stroke and some cancers for certain groups of women, prompting many to seek alternative therapies for symptom relief.
Lifestyle modifications such as regular exercise, weight loss and drinking fewer caffeinated beverages can help cut down on hot flashes, according to Levis.