News Flash on Hot Flashes
The change of life. . .the suspension of menses. . . THE MENOPAUSE! I’m 46 and not yet experiencing the symptoms of menopause, but it’s one of my favorite topics to research as this phase of life is inevitable, and I’d like to set myself, and others, up for a successful transition!
While hormone replacement therapy (HRT) is a common way to alleviate some of the less than pleasant symptoms of menopause, such as hot flashes, I am most interested in diet and exercise interventions to ease these menopausal indicators.
The WAVS Study
In the vein of nutritional interventions for symptoms of menopause, I recently read an original study titled
“The Women’s Study for the Alleviation of Vasomotor Symptoms (WAVS): a randomized, controlled trial of a plant-based diet and whole soybeans for postmenopausal women,” published in April of 2021 in the journal Menopause. (1)
The term “vasomotor” simply refers to the constriction or dilation of blood vessels, and vasomotor symptoms (VMS) are commonly referred to as hot flashes or flushes, and night sweats.
The authors begin by referencing data from the 1980s that showed women in Japan, who primarily ate a plant-based diet with a lot of soy foods, had significantly fewer hot flashes than women in Western countries who primarily ate a Western-style diet heavy with animal origins and processed foods. In subsequent years, meat, dairy, protein, and fat consumption all increased in Japan. The authors explain
“Dietary changes in Japan were paralleled by changes in menopausal symptoms. In a 2005 study, hot flashes were reported twice as frequently as in the 1980s. . . . Despite Westernization, soy intake remains much higher in Japan, compared with the United States, suggesting that overall dietary changes, rather than changes in soy intake, may be responsible for the increasing vasomotor symptom frequency.”
So this team of researchers wanted to home in, not just on soy consumption, but also a lower-fat, plant-based (vegan) diet with a soy supplementation.
Who’s being Studied?
Let’s first look at who the researchers were studying, specifically, “postmenopausal” women. To understand this term, we need to understand all THREE phases of natural (vs medically or surgically induced) menopause.
(1) Perimenopause - or the menopause transition - can start 8 to 10 years before menopause and is characterized by ovaries producing less estrogen. It lasts until the ovaries stop producing eggs.
(2) Menopause - the phase when ovaries stop being produced and women stop menstruating. A woman has to have gone 12 consecutive months without a period to be considered in menopause.
(3) Postmenopause - the phase where a woman hasn’t menstruated for a year, and specifically the population researched for this original study.
The participants were postmenopausal women, specifically aged 40 to 65 with moderate to severe hot flashes at least twice daily and no periods in the preceding 12 months. The criteria that excluded people from participating in this study included: use of hormonal medication in the previous two months, smoking, substance abuse, history of an eating disorder, use of weight loss meds in the preceding 6 months, women currently trying to lose weight, BMI less than 18.5 kg/m2, soy allergy, and current consumption of a low-fat, vegan diet with daily soy consumption.
What’s being studied
The objective of the WAVs study was to
“assess the effects of the combination of a low-fat plant-based diet and soybeans on the frequency and severity of menopausal hot flashes.”
The Dietary Intervention
Participants in the Intervention group (the group who had diet modifications vs the Control group of participants who altered nothing about their diet) were asked to adhere to a
“low-fat, vegan diet, based on fruits, vegetables, whole grains, and legumes and to minimize added oils and fatty foods (eg nuts, nut butters, and avocados).”
In addition, the participants in the intervention group were asked to consume 1/2 cup of whole, cooked soybeans on a daily basis. Alcoholic beverages were limited to 1 per day, and a B12 supplement was provided to the women following the vegan diet in the Intervention group.
Restrictive or Just Right?
So right there, you’ve got a prescriptive and possibly difficult dietary lifestyle for a lot of women to follow. This doesn’t render the study invalid so much as it may not be generalizable to a large population of women, unless they are willing to make what could be considered drastic changes to diet. While I typically eat a low-fat vegetarian diet with an emphasis on fruits, vegetables, whole grains, and legumes, it would be really tough to “minimize the added oils,” nuts, nut butters, and avocados, as well as dairy. And while I don’t drink alcohol, I know plenty of women who would find limiting their alcohol intake to one drink a day restrictive at best. One generalizable aspect of this diet is that besides the soybeans, no other foods were provided to the participants, showing that this IS a diet that could be followed in a home, rather than a clinical setting, for at least 12 weeks.
What Did the Results Show?
The results are promising. Here’s how the results differ between the Intervention and Control Groups.
Weight Loss: Mean body weight decreased by 3.5 kg in the Intervention group and increased by 0.8 kg in the Control group
Physical activity: No significant change in either groups
Frequency of Total Hot Flashes: (Number of hot flashes) Decreased 79% in the Intervention group and 49% in the Control group
Moderate-to-severe Hot Flashes: (Severity) Decreased 84% (from 4.9 to 0.8/day) in the Intervention Group and 42% (3.8 to 2.2/day) in the Control Group. (It’s interesting to note here that apparently, overall, the participants in the intervention group were experiencing more moderate to severe hot flashes than those in the control group at the start of the study).
Nighttime Moderate-to-Severe Hot Flashes: In the Intervention group, 59% (10/17), became free of nighttime moderate-to-severe hot flashes during the 12-week intervention. For those in the Control group, there was no change in nighttime moderate-to-severe hot flashes during the intervention period. Being that night-sweats are a typical culprit of sleep disturbances in menopausal and postmenopausal women, this could be a promising insight for sufferers of night sweats.
Limitations of the Study
The Limitations section of a research article is my favorite because it really shows how self aware and transparent the authors are about their study design. For this WAVs study, the authors declare the limitations of the study are its small sample size, a possible placebo effect, and inability to reveal long-term effects because the intervention was only 12 weeks in length.
Regarding the limitation of the sample size, sample size (whether small or large) doesn’t necessarily speak to the accuracy of a study, whereas the effect size, which is independent of sample size, can indicate strength or weakness of association. Specifically, the larger the effect size, the stronger the relationship between two variables, such as diet and hot flashes. The effect size for vasomotor symptoms in this study was -2.5, which shows a strong association. *
Authors’ Conclusion
The authors concluded their article with this:
“The combination of a low-fat plant-based diet and whole soybeans was associated with reduced frequency and severity of hot flashes, the elimination of moderate-to-severe hot flashes for the majority of participants, and quality-of-life improvements in vasomotor, psychosocial, physical, and sexual domains.”
They further suggest more studies are needed, specifically regarding
“. . . to identify the relative roles of a plant-based diet and soy supplementation, and the role of diet-induced microbiome changes in isoflavone metabolism.”
Personally, I’d love to see more studies on the alleviation of hot flashes with less restrictive diets, such as a vegetarian diet that includes fish and low- or non-fat dairy, along with the addition of soybeans or other soy-based products such as soy milk and tofu.
What Do the Results Mean for Us?
So what does this mean for us ladies ranging from pre-menopausal to post-menopausal? The take-aways for me would be that once hot flashes start, and if they become a problem, it would be good to:
1) Start journaling the frequency and severity of hot flashes and night sweats (vasomotor symptoms) when they occur. The WAVs study asked participants to record their hot flashes using the My Luna mobile app.
2) Consider increasing whole foods and decreasing animal-based foods, for an emphasis on a plant-based diet.
3) Consider decreasing fatty oils, and fatty foods including nuts, nut butters, coconut, avocados, etc
4) Increase consumption of soy, specifically whole cooked soybeans (1/2 cup), in your diet.
Note, edamame, which are immature green soybeans, are not the same as whole, mature soybeans that were used in this study. According to a post on the Harvard T.H. Chan School of Public Health, 1/2 cup of whole, cooked soybeans has an isoflavone content almost 3 time as what you would get in the same serving of edamame. (2)
Until next time. . .
Thanks for taking the time to stop by QuickBites and learn how changes to your diet can ease hot flashes!
REFERENCES
(1) Neal D. Barnard, MD, FACC,1,2 Hana Kahleova, MD, PhD,1 Danielle N. Holtz, BS,1, Fabiola del Aguila, PhD,1 Maggie Neola, BS, RD,1 Lelia M. Crosby, BA, RD,1, and and Richard Holubkov, PhD3. “The Women’s Study for the Alleviation of Vasomotor Symptoms (WAVS): A Randomized, Controlled Trial of a Plant-Based Diet and Whole Soybeans for Postmenopausal Women.” Menopause: The Journal of The North American Menopause Society Vol. 28, no. No. 10, pp. 000–000 (February 25, 2021). https://doi.org/DOI: 10.1097/GME.0000000000001812.
(2) Boston, 677 Huntington Avenue, and Ma 02115 +1495‑1000. “Straight Talk About Soy.” The Nutrition Source, August 6, 2018. https://www.hsph.harvard.edu/nutritionsource/soy/.
(*) You can read more Effect Size here:
Sullivan, Gail M., and Richard Feinn. “Using Effect Size—or Why the P Value Is Not Enough.” Journal of Graduate Medical Education 4, no. 3 (September 2012): 279–82. https://doi.org/10.4300/JGME-D-12-00156.1.
and
“What Does Effect Size Tell You? | Simply Psychology.” Accessed August 28, 2021. https://www.simplypsychology.org/effect-size.html.