Wednesday Bubble: Soy takes another hit
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Welcome to the new home of Flashfree! Our URL has changed but the same content that you’ve grown to know and ‘love’ is the same.
Let’s kick off http://flashfree.me with the latest and ‘greatest’ report on soy: it does not help menopausal symptoms or prevent bone loss.
Isn’t this contrary to what’s been reported previously, at least with regards to women with the ability to produce S-equol?
In this latest nail to the soy coffin, research appearing in the Archives of Internal Medicine suggests that part of the issue in proving or disproving the utility of soy for menopause is the lack of trials of long duration, consistent use of low doses of soy isoflavones, small number of participants and too much breadth and depth of age and menopausal status. However, the SPARE trial (Soy Phytoestrogens as Replacement Estrogen), aimed to change this paradigm by examining the effect of daily 200 mg soy isoflavones in tablet form in 248 women between the age of 45 and 60. All participants had been in menopause for one to five years or for six to 12 months. These women were studied for two years, were instructed to take the active pill or placebo tablet before breakfast, and stop taking any hormones for at least six months before the study started. Calcium was supplemented in women who were taking less than 500 to 1000 mg daily. Importantly, women taking the isoflavone tablets were actually receiving a dose equal to approximately twice that normally obtained through food in Asian diets.
At the study’s end, the researchers found that women taking soy or placebo were on equal footing and that soy did not appear to prevent bone loss or reduce bone turnover. Moreover, soy did not appear to have any significant effect on hot flashes, night sweats, libido or vaginal dryness. They also say that even though women who are able to produce S-equol in their guts were likely to benefit from soy compared to women who are not, they did not see any specific benefit when these women were studied separately. Although not considered a dangerous side effect, constipation was experienced by more than a third of women taking soy.
So, what are we to think? Some studies say soy is effective, particularly among S-equol producers while others, like this well designed trial, show that it is now. However, there has been some data suggesting that the ratio of specific isoflavones may play an important role, and there is no information in the published study about this ratio other than to say that the soy supplement used is similar to those obtained in health food stores.
When it comes to soy, the verdict isn’t quite out yet, although the studies that have been conducted to date can’t seem to tease out what’s what. As always, use caution and lower your expectations. There are other non-hormonal approaches that may provide greater benefit when it comes to bone loss and menopausal hot flashes and other symptoms.
Want to read more on soy isoflavones? Check out the Flashfree archives.
Read MoreMore on soy? Oh joy!!
A close friend of mine wrote me the other day to tell me about an article she had seen. In it, the author claims that using soy sauce will help to alleviate hot flashes. However, the author neither backs this claim with any evidence or provides information on how much soy sauce you’d need to obtain the minimal level typically associated with some sort of reduction in menopausal symptoms.
Because there’s a ton of bad information floating around the interwebz, I wanted to break it down for you, right here and now. I also encourage you to peruse the archives because I’ve written a ton of posts on soy isoflavones.
Here’s what we know thus far about soy and soy isoflavones:
- Soy isoflavones are plant-based compounds that are believed to mimic the action of natural estrogen in the body. Therefore, researchers have been dissecting and studying the properties of soy for years in order to determine if this alternative to hormone replacement can help alleviate hot flashes and night sweats, and possibly even promote bone health in menopausal women.
- The deeper researchers delve into the properties of soy, the more they are learning. For example, the ratio of the most plentiful soy isoflavones, i.e. daidzein and gensistein, are important, and a metabolite of daidzein called S-equol appears to be the most potent in terms of preventing flashes and sweats. S-equol is produced in the gastrointestinal tract however the ability to actually manufacture it depends on the presence of certain microflora. Consequently, only 30% to 60% of individuals are actually able to produce S-equol on their own (although this figure is believed to be higher among Asians and vegetarians).
- Studies that have examined the role of a soy-based diet, mostly among Asian populations, typically focus on four main foods that are rich sources of soy isoflavones: tofu, miso (fermented soybean paste), natto (sticky, fermented soy food rich in vegetable protein) and fried tofu. Soy sauce and soy oil do not contain isoflavones! Therefore, using either in cooking will not prevent hot flashes or night sweats.
- In a more recent review of soy products published in the American Journal of Epidemiology, researchers evaluated the dietary habits of 1,106 Japanese women between the ages of 35 and 64 over six years to determine a possible association with hot flashes or lack thereof. All participants were asked to record what they were eating as well as the serving size; included were nine specific soy products (miso soup, tofu, deep-fried tofu, fried bean curd, dried bean curd, natto, houba miso, soy milk and boiled soybeans).
The findings? There was an inverse association between eating soy and hot flashes – those women eating the greatest amount of soy, i.e. 115.9 grams/day, that contained the greatest amount of isoflavones, i.e. 50.8 grams/day, had the highest amount of protection against developing hot flashes and a 6% lower risk than women who consumed the least amount for developing hot flashes over the course of the study. Moreover, the results were upheld even after researchers accounted for factors such as age, menopausal status and total daily caloric intake. Notably, if soy sauce or oil actually contained isoflavones, an individual would have to consume at least 4 ounces of soy sauce daily to obtain any benefit.
Most importantly, when it comes to soy, even supplements aren’t created equal. If you are going to go that route, speak to a licensed practitioner who specializes in herbal medicine and look for a supplement that notes standardized manufacturing on its label. Simply walking into a drugstore to make a purchase is a sure way to guarantee that skimping on price often means skimping on quality.
There’s a lot more we need to learn about soy before making blanket recommendations. Soy is more complex than researchers originally thought. And a few drops a day? No way!
Read MoreDem bones! Isoflavones, S-equol and aging
I love it when readers of this blog point me to research that I might have missed or just not stumbled across. That happened a few weeks ago after I wrote a post on soy and safety. By following the links, reader Carol Land directed me to a newly published study on S-equol and bone health.
S-equol is a metabolite of a major soy isoflavone called daidzein. It has a particular affinity for estrogen receptors and possesses some estrogen-type activity of its own. S-equol is produced in the gastrointestinal tract however the ability to actually manufacture it depends on the presence of certain microflora. Consequently, only 30% to 60% of individuals are actually able to produce S-equol on their own (although this figure is believed to be higher among Asians and vegetarians).
The surge in interest in S-equol is related to its potential for augmenting the benefits of isoflavones; in fact, it is possible that women who are naturally producers of S-equol actually experience greater effects from soy products, and this is especially true when it comes to bone health.
I cannot stress enough the importance of bone health as we age. Declining levels of estrogen are a primary cause of bone loss and resulting osteoporosis in women; indeed, one in five American women over the age of 50 have osteoporosis and about half will experience a fracture in the hip, wrist or spine as a result. What’s more, because osteoporosis is silent in its early stages, causing no symptoms, it’s critical that bone loss is halted or at least slowed either before or during the most critical phases strike. There is no time like the present to take preventive measures, even if you are in your 30s and 40s.
Where does S-equol fit in?
For the first time, researchers have shown the daily S-equol supplements taken by women who are not naturally producers of S-equol, may improve bone metabolism and attenuate bone loss!
In this 1 year study of 356 healthy, postmenopausal Japanese women between the ages of 41 and 62, daily intake of 10 mg S-equol via supplement markedly reduced markers of bone resorption in blood and urine compared to women taking placebo pills or 2 mg or 6 mg of S-equol daily. In fact, in women taking the 10 mg dose for a year, declines in a urinary marker of bone resorption (i.e. DPD) were roughly 21% greater compared to placebo. Measures of whole body bone mineral density also showed that S-equol supplementation protected against bone loss, although not to the extent as bone resorption. These results remained even after changes in height, weight, body mass index, lean and fat mass were accounted for. No participant experienced serious side effects from taking S-equol and hormone levels were not adversely affected.
Does this mean that you should rush out and purchase S-equol supplements?
One of the primary limitations of this study is that the process of bone recycling can take as long as 18 months and the time required to complete a cycle may actually increase with age. Thus, the duration of time that the women were studied might be too short to draw any definitive conclusions. Hence, you may want to wait before you start taking S-equol. However, the evidence that’s building continues to put the weight on the benefits versus risks side. Only time will tell. Meanwhile – here’s to your bone health. Keep on doing all you can do to keep dem bones.
Read MoreSoy. Is it safe?
For years, researchers have been exploring the potential of soy isoflavones — naturally-occurring plant estrogens — for alleviating menopausal symptoms such as hot flashes, atrophy and bone loss. Thus far, certain components of soy, including genestein and S-equol have shown the most promise. However, are they safe? And, as the adoption of soy as a viable alternative to risk-ridden hormone replacement therapy continues to grow, and women turn to supplements rather than food-based soy, is there anything that they need to worry about in terms of side effects?
Researchers recently evaluated this question in a study of 403 postmenopausal women who took either 80 mg soy tablets, 120 mg soy tablets or placebo tablet daily for two years. The particular type of soy isoflavones used were hypocotyl isoflavones, which are a byproduct of soy protein and (very rich in daidzein – the second most plentiful isoflavone in soy. The effects of the supplements were measured at the study’s start, at one year and at the end via blood tests and a well-woman examination (i.e. mammogram, pap smear, x-rays to measure bone density). A smaller group of women also had ultrasounds done to determine any possible effects on the lining of the uterus or development of fibroids.
Although the primary goal of the study was to determine the effects of this type of soy supplement on osteoporosis and bone loss, the researchers discovered that taking soy supplements during this time period did not present any major risk to health and did not affect thyroid function. Although one participant developed breast cancer during the study and one, endometrial cancer, 1) utrasounds in the subgroup of women who received them did not show any uterine thickening and 2) the rate of cancer development in this study, only two women over a two year time period, was considerably lower than statistically likely in a general population of women. Both of these factors support the contention that soy isoflavones are not likely to promote either cancers.
So, is soy safe over the long-term? It appears that it is. HOWEVER, bear in mind that the type of soy used in this study is are very different that the type that is commonly sold over the counter, which commonly contain higher percentages of genistein, the most plentiful isoflavone component in soy.
And what about osteoporosis? This particular paper did not address those specific results, although others have. Thus far, the results have been mixed. However, this particular study, better known as OPUS (Osteoporosis Prevention Using Soy)is one of the largest and most comprehensive to date and those findings are likely to come to light soon.
In the interim, if you are going to be taking soy in supplement form, be mindful that your exposure is likely to be as one to four times that a typical Asian diet and as much as 100 times that of a typical Western diet. While these level do not appear to be harmful, herbal and plant medicines are not without risk so as always, the rule of thumb is be vigilant and speak to a health practitioner first.
Read MoreNewsflash: hot flashes and soy…more on genistein
There’s some exciting news on the soy isoflavones front: for the first time, researchers have shown that a synthetic formulation of genistein, a plant-based estrogen component of soy, may actually reduce both the frequency and severity of hot flashes. Genistein is an interesting isoflavone, in that studies have linked it to some truly potentially important benefits, including preventing or reducing heart disease risk and attenuating bone loss in menopausal women. While the verdict is still out on its role in these conditions, it does appear to influence hot flashes and only in the best way possible! Moreover, this is the first time that a synthetic formulation has shown to have some degree of benefit in this regard.
Granted, this is a small study of only 84 menopausal women, 40 of whom took synthetic genistein for 12 weeks and 40 who took a sugar placebo tablet. The results? By the study’s end, women taking 1, 30-mg capsule daily reduced the number of hot flashes by half (51%, from about 10 per day to 5 per day) and also experienced significant declines in how long they lasted. The synthetic formulation, which was standardized, was also shown to be safe and did not detrimentallly impact the lining of the uterus. Notably, however, the researchers did note that there are not enough data to recommend isoflavones to women who’ve had breast cancer or at high risk for developing, even though current data suggest that exposure does not adversely affect breast tissue density or cancer cell proliferation, meaning that it is likely that with more study, they will ultimately prove safe for use in breast cancer patients.
Your key take-away is that there may be a viable option for women who are flashing but want to stay away from hormones. However, this is what we still need to know:
- Will genistein work on larger groups of menopausal women?
- Is formulation important?
- Is the 30 mg dose the lowest dose that will confer these sort of benefits?
- Are there any other factors that these women had in common that might be influencing outcomes?
As with any novel data like these, it’s great to be cautiously enthusiastic. Stay tuned!
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