The findings, published in Menopause: The Journal of the North American Menopause Association, reviewed 19 previous studies that examined more than 1,200 women.
Although the effectiveness of soy in alleviating hot flashes has been inconclusive, with some studies suggesting soy to be beneficial and others suggesting otherwise, much of the discrepancy is due to small sample sizes and inconsistent methodology, according to the authors.
"When you combine them all, we've found the overall effect is still positive," said Melissa Melby, a medical anthropology professor at the University of Delaware and co-author of the study.
Examining the impact of soy isoflavones, chemicals found in soy that exert a mild estrogen-like effect, Melby and her colleagues found:
Ingesting at least 54 milligrams of soy isoflavones daily for six weeks to a year reduces menopause hot flash frequency by 20.6 percent and severity by 26 percent, compared to a placebo.
The total reduction in frequency and severity might be even greater due to the placebo effect.
In longer duration studies (where women consumed soy isoflavones for 12 weeks or more), the decrease in hot flash frequency was approximately threefold greater than in shorter-duration trials.
Isoflavone supplements with higher levels (at least 19 milligrams) of genistein, one of the two main types of isoflavones, were more than twice as effective at reducing hot flash frequency than lower amounts.
Melby called the genistein result particularly notable because the compound is the primary isoflavone in soybeans and soy foods, suggesting that, "Eating soy foods, or using supplements derived from whole soybeans, may work better for women."
Each gram of soy protein in soybeans and traditional soyfoods provides approximately 3.5 mg of isoflavones. Two glasses (16 oz) of soymilk or seven ounces of tofu provide approximately 50 mg of isoflavones.
The interest in soy and menopause stems from observational evidence in Japan, where researchers have found the low frequency of hot flashes in Japanese women might be attributed to the high soy consumption that often begins in utero and continues throughout their lifespan.
"Soy is probably more effective in these women," Melby said. "But if you're 50 and you've never touched soy, it's not too late. We've found that it still helps."
Andrea Boyle Tippett | EurekAlert!
The importance of biodiversity in forests could increase due to climate change
17.11.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig
Win-win strategies for climate and food security
02.10.2017 | International Institute for Applied Systems Analysis (IIASA)
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
20.11.2017 | Life Sciences
20.11.2017 | Materials Sciences
20.11.2017 | Life Sciences