Full Transcript NutritionFacts Introduction 0:00 Doesn't it seem like when it comes to nutrition, there are more opinions than 0:04 [music] facts to go around? Every day we hear new theories about 0:08 diets and supplements and >> [music] 0:10 >> best foods to eat. Well, my role is to take the mystery out of good nutrition 0:15 and look at the science. Welcome to the NutritionFacts Podcast. I'm your host, 0:20 Dr. [music] Michael Greger. Today we look at how specific foods have 0:25 been shown in [music] randomized controlled trials to improve the 0:27 symptoms of menopause. There's a great variety of symptoms 0:32 suffered by women undergoing menopause. There's the so-called vasomotor symptoms 0:37 like night [music] sweats and hot flashes, difficulty sleeping or full-on 0:41 insomnia, vaginal dryness and pain during sex, as well as adverse effects 0:45 on mood including full-blown depression. Might exercise help? Exercise can 0:51 certainly help with physical and psychological quality of life in 0:54 general, but unfortunately, there's no evidence for the effects of exercise on 0:58 menopause specific symptoms. You know, researchers are getting 1:02 desperate when they try to see if giving people pig placenta will help. Spoiler 1:08 alert, it doesn't. 1:10 Well, we know oxidative stress, which is a consequence of excessive free oxygen
Plant-Based Diets and Menopause Symptoms 1:15 radicals or impaired antioxidant defense, is linked not only to diseases 1:19 such as diabetes, obesity, and cardiovascular disease, but also 1:23 menopausal symptoms like hot flashes. Low free oxygen radical defense is 1:28 associated with more menopausal symptoms, just like having a diet with 1:31 more antioxidants is associated with fewer menopausal symptoms. 1:35 In fact, a high intake of fruits and vegetables may delay the onset of 1:39 menopause in the first place, thought to be because the presence of antioxidants 1:43 in fruits and vegetables may counteract the adverse effects of free radicals on 1:46 the number and functional eggs you still have in your ovaries. Whereas the reason 1:50 high meat consumption has been related to degenerative diseases may not just be 1:55 the saturated fat and cholesterol, but the pro-oxidation products generated 1:59 during their production, storage, digestion, and the metabolism 2:04 of meat. Similarly, since a pro-inflammatory diet 2:07 has also been associated with higher menopause specific somatic symptoms, 2:11 meaning like hot flashes and sleep issues, 2:14 that would mean moving towards a more plant-based diet packed with 2:18 anti-inflammatory components like fiber and away from pro-inflammatory foods 2:22 containing saturated fat and cholesterol. No wonder whole plant foods 2:26 intake has been associated with fewer menopausal symptoms. 2:30 In terms of specific foods, poultry and skim dairy products may be particularly 2:35 bad, whereas soy milk seemed to help. So, women may derive benefit from lower 2:40 consumption of poultry and skim dairy and a greater consumption of vegetables 2:44 and soy milk. You don't really know though until you put it to the test. And 2:48 indeed, women randomized to drink soy milk reduced their menopausal symptoms 2:52 by 20% within 12 weeks. No wonder that those eating strictly 2:57 plant-based diets report less bothersome menopausal symptoms. Among women 3:01 undergoing menopause, vegans reported less bothersome symptoms and within the 3:06 diet groups, more vegetables and in the immediate group, less flesh food was 3:10 associated with less bothersome symptoms as well. So, eating a plant-based diet 3:14 may be helpful for women in their menopausal transition who prefer a 3:18 natural means to manage their symptoms. Consistent with all the other studies 3:22 demonstrating reduced menopausal symptoms in those consuming greater 3:26 quantities of plant-based foods and less meat. 3:30 But again, maybe there are other reasons healthier eaters have fewer symptoms. 3:34 You can't prove cause and effect until 3:39 you guessed it, an interventional trial to see if changing your diet actually 3:43 reduces symptoms. And in this study, where women were encouraged to decrease 3:48 fat and increase fruit, vegetable, and whole grain intake, they were 3:51 significantly more likely to eliminate their vasomotor symptoms like hot 3:55 flashes and night sweats compared to the control group. So, it's certainly not 4:00 all or nothing. And within a plant-based diet, those randomized to a meat-free 4:04 diet with daily flaxseed oil, walnuts, and almonds did better than those 4:09 randomized to the same diet, but with daily extra virgin olive oil. After 16 4:13 weeks, the vegetarian diet that was rich in omega-3s did better reducing 4:18 vasomotor symptom frequency. In fact, even just 2 tsp worth of ground 4:22 flaxseeds a day alone can significantly decrease menopausal symptoms to about 4:27 the same extent as hormone replacement therapy, but without the side effects. 4:34 In our next story, does soy food consumption [music] 4:37 explain why Japanese women appear so protected from hot flashes? 4:42 When women hit menopause and their ovaries shut down, the estrogen level in
Soy, Hot Flashes, and Hormone Comparisons 4:47 their body drops 95%. This is good news for the endometrium, the lining of the 4:52 uterus. Otherwise, the constant estrogen signaling could eventually result in 4:57 endometrial cancer. In fact, maybe that's why menopause 5:01 evolved to protect the uterus from cancer. 5:05 Lower estrogen levels are also good for lowering breast cancer risk. In 5:09 postmenopausal women, relatively high blood levels of estrogen are associated 5:13 with more than double the increased risk for breast cancer. 5:18 Estrogen levels drop 95% at menopause, but not to zero because other tissues 5:24 can make estrogen like our own fat cells. This probably explains the 5:29 increase in breast cancer risk in obese postmenopausal women. More fatty tissue 5:34 means more estrogen production. Then we learn that soy phytoestrogens 5:40 can block the production of estrogen such that drinking a glass of soy milk 5:44 with each meal can cut estrogen levels in half in premenopausal women, 5:50 but levels in postmenopausal women are already down 95% and because of that, 5:55 many women suffer from hot flashes. Might lowering levels even further with 6:00 soy make menopausal symptoms even worse? Estrogen treatment very effective 6:06 reducing menopausal symptoms. Unfortunately, the downside is not only 6:11 the uterine cancer, but blood clots, strokes, and cognitive impairment. 6:16 Taking progesterone type compounds with the estrogen helps prevent the uterine 6:21 cancer, but increases the risk of heart attacks, 6:24 more stroke risk, breast cancer, more clots, and dementia. So, what's a woman 6:30 to do? Well, the 80% hot flashes figure is not 6:35 universal. Uh maybe 80 to 85% in European and 6:39 American women, but it may be as low as just 15% in 6:44 places like Japan. In fact, there's not even a word for it in the Japanese 6:48 language, which supports how relatively rare it is. 6:53 Maybe the phytoestrogens in soy are helping? 6:58 The association between soy product intake and the occurrence of hot flashes 7:03 was examined by following a thousand Japanese women before they started 7:06 menopause over time to see who developed hot flashes and who didn't. And those 7:12 women who were eating like 4 oz of tofu a day appeared to cut their risk in half 7:17 compared to women who only ate like an ounce or two a day, suggesting soy 7:20 products are protective. But maybe soy intake is just a marker 7:25 for a healthier diet overall? A study in China found that consumption 7:30 of whole plant foods in general seemed to be associated with decreased 7:34 menopausal symptoms. So, to see if soy was something special, you'd have to put 7:39 it to the test. Studies like this of soy phytoestrogens in pill form showed 7:45 extraordinary results, a significant drop in hot flash presence, number, and 7:49 severity from 100% of women suffering at the beginning to only 31% suffering by 7:55 the end of 3 months. The average number of hot flashes 7:58 dropped from about 120 months down to 12. 8:03 But the problem with studies like these is that there's no control group to 8:07 control for the placebo effect. If you look at all the hormone trials, 8:12 even the women who got the placebo sugar pills had up to a 60% reduction in hot 8:18 flashes over the years. That's why any therapy purported to 8:23 reduce such symptoms must be assessed in blinded trials against the placebo 8:28 because of the large placebo effect. You know, and also because menopausal 8:32 symptoms often decline on their own over time. 8:37 Uh but it's important to recognize how powerful the placebo effect can be. 8:41 Over the past 20 years, more than 50 clinical trials have evaluated the 8:44 effects of soy foods and supplements on the alleviation of hot flashes. 8:49 Compiling the best ones together, the placebo groups got about a 20% drop in 8:53 hot flash severity. The soy groups achieved about a 45% drop. So, on 8:58 average, the soy did about 25% better than control. 9:04 There've been two studies that compared soy phytoestrogens head-to-head against 9:08 hormones, and in one study, they actually seemed 9:11 pretty comparable in terms of reducing hot flashes, muscle and joint pain, and 9:15 vaginal dryness compared to placebo. Though in the other, soy did better than 9:20 placebo, but estrogen and progesterone therapy did better than them both. But 9:27 the soy has the benefit of not increasing cancer, heart disease, and 9:31 stroke risk. Finally today, approximately half of the 9:36 variability of age of menopause among women is explained by genetics, but 9:41 behaviors or circumstances can help explain the rest. Since 1970, 9:47 the proportion of women having their first child after age 35 increased 9:51 nearly tenfold. This may introduce a longevity penalty 9:56 on their children as those born to older mothers don't tend to live as long. But 10:02 mothers having children later tend to live longer themselves. For example, 10:06 female centenarians were found to be nearly four times more likely to have 10:10 had children after age 40 than women who died by their 70s.
Menopause Timing, Genetics, and Lifestyle Factors 10:15 This doesn't necessarily mean delaying kids will make you live longer. Smoking, 10:21 for example, could be a confounder causing both early menopause and early 10:25 death. Or maybe delayed reproductive aging is just a sign of slower aging in 10:30 general. However, some have suggested the biological changes of pregnancy 10:35 might have a rejuvenating effect even going so far as to suggest a parabiosis 10:40 mechanism, bathing in the blood of babies, but just not in a Countess 10:44 Bathory sort of way. To sort between these possibilities, 10:49 researchers studied the longevity of brothers of women who gave birth after 10:53 age 45 and that of their wives. The brothers with late fertile sisters 10:59 lived longer, but their wives did not. This suggests a genetic robustness cause 11:05 rather than a rejuvenation effect. And the fact that the longevity benefit 11:09 didn't extend to their wives suggests it's not due to a confounder like 11:13 socioeconomic strata. On the other hand, women who experience 11:17 extremely early menopause, the 1% who stopped menstruating by age 39, 11:23 may be at risk for diminished longevity and should therefore be counseled to 11:27 adopt a particularly healthy diet lifestyle. 11:31 Approximately half of the variability of age of menopause between women is 11:36 explained by genetics. Other than smoking, what other behaviors 11:41 or circumstances can help explain the rest? 11:45 Factors that don't appear to affect the age of menopause include exercise, 11:50 obesity, alcohol, coffee, or vitamin D status. 11:55 Interestingly, women who've been married tend to arrive at menopause later. Some 12:01 suggest it may be the influence of male pheromones given the fact that exposure 12:05 to male armpit odor makes women's cycles more regular. But turns out that male 12:11 cohabitation alone doesn't appear to matter. It may 12:15 be the sex. Married older individuals tend to have more sex. And indeed, pre- 12:21 and perimenopausal women average age 46 who reported sex weekly were 20% less 12:27 likely to experience menopause over the subsequent decade than those reporting 12:31 sex less than once a month. You can very well imagine how this could 12:36 be a result of reverse causation. Though instead of more sex leading to later 12:41 menopause, a later menopause may have instead led to more sexual engagement. 12:45 The relationship between tobacco use and early menopause is thought to be 12:50 mediated by the toxic effects on the ovaries of the polycyclic aromatic 12:54 hydrocarbons in the smoke. Among non-smokers, 12:59 this PAH exposure is almost entirely from food, mostly grilled, barbecued, 13:04 and smoked meats. Could this explain why in the Harvard 13:07 Nurses' Health Study II, higher plant protein intake was associated with 13:11 significantly lower risk of early menopause? Feed female monkeys a diet 13:16 high in animal protein, not only did they get more atherosclerosis, 13:20 but also an acceleration of ovarian aging. 13:24 Now, in the original Harvard Nurses' Health Study, animal protein consumption 13:27 was associated with infertility such that replacing even 5% of animal protein 13:32 intake with plant protein could potentially cut the risk of infertility 13:35 in half. But in the Nurses' Health Study II, while plant protein appeared to 13:39 delay menopause, animal protein intake was not associated with menopause age 13:44 either way. And in the UK Women's Cohort Study, those eating more animal protein 13:49 were 60% more likely to experience a later menopause. 13:52 The data is similarly conflicting in vegetarians. Some studies found no 13:58 difference or a later age of menopause in vegetarians, but others found an 14:02 earlier age compared to non-vegetarians. For example, the largest study found 14:07 that vegetarians reached menopause at an average age of 50.1 years compared to 14:11 non-vegetarians at 50.7 years. 14:15 As I noted, premature menopause before age 40 may be detrimental for longevity, 14:21 but being a little earlier within the normal range may actually be beneficial 14:26 for cancer risk. At the same age, 14:30 breast cancer risk is about 40% higher in premenopausal compared to 14:34 postmenopausal women, presumably due to higher exposure to the necessary evil 14:39 hormone estrogen. Breast cancer risk is 3% higher for 14:44 every year later a woman starts menopause and 5% higher for every year 14:49 earlier a girl starts menstruating. On average, women whose periods hold off 14:53 until age 15 appear to live the longest. Vegetarian women tend to have lower 14:58 estrogen levels, perhaps due to higher fiber intake, and interventional studies 15:03 show that switching to a more plant-based diet can reduce circulating 15:06 estrogen levels by more than 40%. This could explain why vegetarian girls 15:11 may hit puberty later and why those eating strictly vegetarian not only have 15:16 lower cancer risk overall, but particularly lower risk for 15:19 female-specific cancers. Age of menopause may not be a factor 15:24 though based on an interventional trial randomizing women on the verge of 15:28 menopause, average age 49, to 2 years of a lower fat diet to reduce breast cancer 15:33 risk. The intervention group ended up eating 15:36 more fiber and therefore more plant-based, but though they did 15:39 experience improvements in mammogram findings, the dietary shift failed to 15:44 influence the timing of menopause. Visit nutritionfacts.org/audio 15:50 to see all the podcast episodes with descriptions that include links to the 15:54 associated videos. Sources cited and other details are 15:58 available on each video's page. Information about my books, How Not to 16:02 Die, [music] How Not to Diet, and How Not to Age, is at 16:04 nutritionfacts.org/books. All proceeds of which I get are donated 16:09 directly to charity. And I've got a new book in the publication pipeline, the 16:14 manuscript for How Not to Hurt on diet and lifestyle approaches to pain 16:19 management. It's been handed in and will be published December 15th. I'm going to 16:24 be doing a series of webinars to feature some of the new research that I 16:27 discovered. Sign up for our free newsletter at 16:30 nutritionfacts.org/subscribe to stay updated on when those will be. 16:37 Nutritionfacts.org is a science-based nonprofit and everything on the website 16:41 is free. There are no ads, no corporate sponsorships, no kickbacks. 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Closing Remarks and Resources 16:48 service as a labor of love as a tribute to my grandmother 16:52 whose own life was saved with evidence-based nutrition. We just have 16:56 like a a Wikipedia-type [music] 16:58 nonprofit model where everything's free and we just hope maybe, you know, one in 17:02 a thousand people will find it so valuable that they'll kick in a few 17:05 bucks so we can continue to churn out new content to help you and your family 17:10 be healthier. Thanks for listening.
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