Soy Foods for Menopause Hot Flash Symptoms

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Soy can be considered a first-line treatment for menopausal hot flash and night sweat symptoms.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Is the consumption of soy the reason why there isn’t even a word for hot flash in Japanese, as I explored in my last video? Approximately 80 percent of perimenopausal and postmenopausal women surveyed choose to try natural means to deal with symptoms, and the single most common approach was soy. But does it work?

Outside of an Asian context, soy milk may be a greater source of isoflavones than soy foods, and that seems ready-made for a randomized trial against dairy milk or another plant milk control. Soy milk consumption has been associated with fewer hot flashes and night sweats, and skim milk with worse menopausal symptoms. But when actually put to the test against each other, there does not appear to be any difference. There have been studies showing that randomizing women to soy milk can reduce hot flashes and vaginal symptoms as much as 70 percent compared to the control group. But without a placebo control, we’re not sure how much of that is the placebo effect.

To truly blind study subjects, soy isoflavones were extracted out and stuffed into capsules, to be pitted against identical looking “sugar pill” placebo capsules. More than a dozen such clinical studies have been performed—randomized double-blind, placebo-controlled trials—and indeed, the equivalent of about two servings of soy foods a day worth reduces hot flash frequency by about 20 percent more than placebo, and hot flash severity by around 25 percent more than placebo––compared to more like a 30 to 40 percent net reduction from estrogen hormone therapy. Soy isoflavones have also been shown to improve other menopausal concerns, including vaginal dryness, bone loss, memory, and cognitive functions more generally, as well as depression.

There have been a few trials in which soy was pitted head-to-head against hormone therapy. One found their efficacy comparable, in terms of reducing hot flashes, muscle and joint pain, and vaginal dryness. In the other, hormones worked twice as well––a 54 percent reduction in hot flash scores taking the standard estrogen/progesterone combination, compared to 24 percent over placebo in the soy isoflavone group. Not only did the hormones work better, but they can work quicker. Three months are required for soy isoflavones to achieve half their maximal effect, whereas the same is achieved after just three weeks with estrogen. Of course, soy has the benefit of no increased risk of cancer and clots; in fact, if anything, a reduction in breast cancer risk throughout the lifespan, and lower risk of cardiovascular disease.

The bottom line, wrote one consensus panel of experts, is that soy can be considered a first-line treatment for menopausal hot flash and night sweat symptoms. One convenient whole food source of soy is soy nuts, which are dry roasted soybeans. Harvard Medical School’s Center of Excellence in Women’s Health funded a randomized crossover study of a half cup of unsalted soy nuts a day (divided into three or four portions, and spaced throughout the day) and achieved a 50 percent reduction in hot flashes within two weeks. What’s inconvenient about soy nuts is the formation of advanced glycation end products in the roasting process––though about four times less than that of roasted real nuts, or other roasted legumes, and ten times less than a serving of something like roasted chicken. But something like edamame or canned soybeans would be better.

Some menopausal women use isoflavone supplements, but most just add soy foods to their diet. I think that’s the way to go. Supplement mislabeling and contamination issues aside though, isolated isoflavones have been shown to improve artery function and decrease high blood pressure. Soy foods can also lower LDL cholesterol, which may explain the lower associated cardiovascular disease risk. Besides the lower breast cancer risk, soy eaters are also less likely to get prostate cancer, colorectal cancer, and lung cancer.

In a previous video, I noted that those eating plant-based tend to have significantly fewer hot flash-type symptoms. What if you combined a plant-based diet and soybeans? Two randomized controlled trials found that reduced-fat plant-based diets with a daily half cup serving of cooked whole soybeans can reduce the number of serious hot flashes by 84 to 88 percent within twelve weeks. Overall, most randomized to the plant-based group ended up free of moderate-to-severe hot flashes, compared to about 95 percent still suffering in the control group.

Please consider volunteering to help out on the site.

Motion graphics by Avo Media

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Is the consumption of soy the reason why there isn’t even a word for hot flash in Japanese, as I explored in my last video? Approximately 80 percent of perimenopausal and postmenopausal women surveyed choose to try natural means to deal with symptoms, and the single most common approach was soy. But does it work?

Outside of an Asian context, soy milk may be a greater source of isoflavones than soy foods, and that seems ready-made for a randomized trial against dairy milk or another plant milk control. Soy milk consumption has been associated with fewer hot flashes and night sweats, and skim milk with worse menopausal symptoms. But when actually put to the test against each other, there does not appear to be any difference. There have been studies showing that randomizing women to soy milk can reduce hot flashes and vaginal symptoms as much as 70 percent compared to the control group. But without a placebo control, we’re not sure how much of that is the placebo effect.

To truly blind study subjects, soy isoflavones were extracted out and stuffed into capsules, to be pitted against identical looking “sugar pill” placebo capsules. More than a dozen such clinical studies have been performed—randomized double-blind, placebo-controlled trials—and indeed, the equivalent of about two servings of soy foods a day worth reduces hot flash frequency by about 20 percent more than placebo, and hot flash severity by around 25 percent more than placebo––compared to more like a 30 to 40 percent net reduction from estrogen hormone therapy. Soy isoflavones have also been shown to improve other menopausal concerns, including vaginal dryness, bone loss, memory, and cognitive functions more generally, as well as depression.

There have been a few trials in which soy was pitted head-to-head against hormone therapy. One found their efficacy comparable, in terms of reducing hot flashes, muscle and joint pain, and vaginal dryness. In the other, hormones worked twice as well––a 54 percent reduction in hot flash scores taking the standard estrogen/progesterone combination, compared to 24 percent over placebo in the soy isoflavone group. Not only did the hormones work better, but they can work quicker. Three months are required for soy isoflavones to achieve half their maximal effect, whereas the same is achieved after just three weeks with estrogen. Of course, soy has the benefit of no increased risk of cancer and clots; in fact, if anything, a reduction in breast cancer risk throughout the lifespan, and lower risk of cardiovascular disease.

The bottom line, wrote one consensus panel of experts, is that soy can be considered a first-line treatment for menopausal hot flash and night sweat symptoms. One convenient whole food source of soy is soy nuts, which are dry roasted soybeans. Harvard Medical School’s Center of Excellence in Women’s Health funded a randomized crossover study of a half cup of unsalted soy nuts a day (divided into three or four portions, and spaced throughout the day) and achieved a 50 percent reduction in hot flashes within two weeks. What’s inconvenient about soy nuts is the formation of advanced glycation end products in the roasting process––though about four times less than that of roasted real nuts, or other roasted legumes, and ten times less than a serving of something like roasted chicken. But something like edamame or canned soybeans would be better.

Some menopausal women use isoflavone supplements, but most just add soy foods to their diet. I think that’s the way to go. Supplement mislabeling and contamination issues aside though, isolated isoflavones have been shown to improve artery function and decrease high blood pressure. Soy foods can also lower LDL cholesterol, which may explain the lower associated cardiovascular disease risk. Besides the lower breast cancer risk, soy eaters are also less likely to get prostate cancer, colorectal cancer, and lung cancer.

In a previous video, I noted that those eating plant-based tend to have significantly fewer hot flash-type symptoms. What if you combined a plant-based diet and soybeans? Two randomized controlled trials found that reduced-fat plant-based diets with a daily half cup serving of cooked whole soybeans can reduce the number of serious hot flashes by 84 to 88 percent within twelve weeks. Overall, most randomized to the plant-based group ended up free of moderate-to-severe hot flashes, compared to about 95 percent still suffering in the control group.

Please consider volunteering to help out on the site.

Motion graphics by Avo Media

Doctor's Note

If you missed the previous video, see Menopausal Hot Flashes Are Not Inevitable. 

What about soy and breast cancer? See my video Is Soy Healthy for Breast Cancer Survivors?

I recently did a series on vaginal menopause symptoms, including: 

For more on how to live your longest, healthiest life, preorder my new book How Not to Age. (As always, all proceeds I receive from all of my books are donated to charity.)

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