Soy isoflavones in foods or supplements, and some herbal remedies may help reduce menopause symptoms like hot flashes and vaginal dryness, according to a review of 62 studies.
But not all complementary therapies have an effect.
"Hot flashes, night sweats and vaginal dryness are very common symptoms of menopause, affecting up to 80 percent of menopausal women," said senior author Dr. Taulant Muka of Erasmus University Medical Center in Rotterdam, The Netherlands. "Many women in Western countries try herbs or other products from plants to manage these symptoms," he noted, but these "natural" products may not necessarily be useful or safe.
"Our results simply indicate that some plant-based therapies, such as soy and red clover, can be beneficial in reducing menopausal symptoms, but some others not (e.g. black cohosh and Chinese medicinal herbs)," Muka told Reuters Health by email.
The researchers extracted data from 62 randomized controlled trials of plant-based alternative therapies and their effects on hot flashes, night sweats and vaginal dryness: 36 addressed phytoestrogens - estrogenlike molecules from plants such as soy or red clover, 16 tested black cohosh and 10 tested other medicinal herbs.
Together, the trials included more than 6,600 women ranging in age from 18 to 75 years old, and followed for between four weeks and two years.
Using phytoestrogens was associated with fewer hot flashes during the day and with less vaginal dryness, but did not influence night sweats.
Some studies tied black cohosh therapies to a lessening of overall menopause symptoms score but not specifically to fewer hot flashes or night sweats. Chinese medicinal herbs were not associated with a decrease in menopause symptoms, according to the results in JAMA.
In early postmenopause, hormone replacement is an effective therapy for menopausal symptoms, Muka said, but it may not be an option for women at increased risk of breast cancer.
Phytoestrogens like those found in soy can act like estrogen in the body, Muka said. "This may explain the aggregate beneficial effects on menopausal symptoms we found for phytoestrogens."
The long-term efficacy and safety of these plant-based therapies is unclear, however, and "healthy lifestyle changes form the backbone for easing the discomfort related to menopausal symptoms and keeping you healthy in the long run," he said.
You should discuss any natural or herbal products with your doctor before taking them, and ask about potential medication interactions, Muka added.
There is little evidence for long-term effectiveness - or risks - of plant based therapies, since most studies only last 12 to 16 weeks, he said.