I don't want breasts on my hairy chest
May 31, 2013 4:46 PM Subscribe
Should men be concerned about consuming a Venti cupful of soy on a daily basis?
I've read questions here before about soy and women, but not about soy and men.
Since soy contains phytoestrogens (isoflavones) that may mimic the activity of the hormone estrogen (or so I've read), are there any possible/likely impacts on a man's health or physiology that he should be concerned about if he consumes, say, the equivalent of one Starbucks Venti cup of soy every day?
I'd like the answers just to address the estrogen aspect since I'm already aware of other nutritional aspects of soy such as sugar and fat.
Thank you.
I've read questions here before about soy and women, but not about soy and men.
Since soy contains phytoestrogens (isoflavones) that may mimic the activity of the hormone estrogen (or so I've read), are there any possible/likely impacts on a man's health or physiology that he should be concerned about if he consumes, say, the equivalent of one Starbucks Venti cup of soy every day?
I'd like the answers just to address the estrogen aspect since I'm already aware of other nutritional aspects of soy such as sugar and fat.
Thank you.
As a biologist, I agree with treehorn+bunny based on what I've read in the literature. Early reports to that effect were based on (weak) rodent studies.
posted by Cygnet at 5:01 PM on May 31, 2013
posted by Cygnet at 5:01 PM on May 31, 2013
The Weston A. Price Foundation/WAPF is the source of this pernicious myth. I find this breakdown to be plain and helpful whenever someone asks me this question (I get it a lot because I'm vegan and maybe we eat more soyfoods, I think?).
Here is a video of Mark Messina (author of the above-linked Soybean isoflavone exposure... paper), summarized: "Clinical research shows that soy does not lower testosterone levels, raise estrogen levels or affect sperm count."
The Vegan R.D. briefly discusses soy and estrogen, accompanied by an exhaustive list of references.
Enjoy your soy!
posted by divined by radio at 5:06 PM on May 31, 2013 [2 favorites]
Here is a video of Mark Messina (author of the above-linked Soybean isoflavone exposure... paper), summarized: "Clinical research shows that soy does not lower testosterone levels, raise estrogen levels or affect sperm count."
The Vegan R.D. briefly discusses soy and estrogen, accompanied by an exhaustive list of references.
Enjoy your soy!
posted by divined by radio at 5:06 PM on May 31, 2013 [2 favorites]
Anecdote: I was on a soy-heavy diet for a while, and I found that it made me anxious and mood-swingy. I can't say it was because of the phytoestrogens, but it happened.
The theory is that the phytoestrogens compete with endogenous estrogen, binding to the estrogen receptors in our systems but not actually doing what the estrogen is supposed to do. Whether this is true or not, I don't know.
posted by gjc at 5:14 PM on May 31, 2013
The theory is that the phytoestrogens compete with endogenous estrogen, binding to the estrogen receptors in our systems but not actually doing what the estrogen is supposed to do. Whether this is true or not, I don't know.
posted by gjc at 5:14 PM on May 31, 2013
You gotta eat a lot o' soy for the bad effects. From VeganHealth.org:
posted by daveliepmann at 5:34 PM on May 31, 2013 [1 favorite]
Summary: It requires twelve servings of soy (and probably much more for most men) to have any sort of noticeable feminizing effects. While one epidemiological study raised concerns about soy and sperm quantity (14), two clinical studies have shown no effects of soy on sperm quality or quantity (15, 126).It seems that in large amounts soy may have feminizing effects. But I don't claim any expertise and will be reviewing the papers cited above.
Case Reports
In 2011, there was a case report of a 19-year old vegan male who was eating a great deal of soy foods - enough to provide 360 mg of isoflavones per day, the equivalent of about 14 servings (10). He also had type 1 diabetes. After eating this way for a year, he developed low free testosterone levels and erectile dysfunction. After ceasing the soy products (and vegan diet), his symptoms normalized within a year. Interestingly, his thyroid hormone appeared normal 15 days after ceasing the diet (though was not measured while on the diet). Of course, there was no reason why he needed to stop being vegan rather than just cutting way down on, or eliminating for a period, soy foods.
A 2008 case report described a 60 year old man who developed gynecomastia (the enlargement of the mammary glands in a male) after drinking 3 quarts of soymilk (the equivalent of 12 servings) a day (123). His breasts returned to normal after discontinuing the soymilk.
Gynecomastia - Male Breasts
In contrast to the case report above, in a 2004 study, 20 men with prostate cancer were given either 450 mg (amount found in about 18 servings of soy) or 900 mg (amount found in about 36 servings of soy) of isoflavones for 84 days (124). Two of the men, who had no gynecomastia at baseline, receiving the 900 mg developed mild cases of gynecomastia. One man was taking a drug that likely increased the gynecomastia. Two men had hot flashes probably related to the isoflavones. Given the very large amounts of isoflavones they were taking, this study should allay fears of feminization in men rather than cause any sort of alarm.
posted by daveliepmann at 5:34 PM on May 31, 2013 [1 favorite]
Treehorn+Bunny cited research to demonstrate soy has no adverse effects in men. There are two problems, however:
1. Medical conclusions are often revised given new, better research and methods. At times, to opposite conclusions.
2. There are verified cases of men legitimately suffering from breast growth and related hormonal changes. Note, soy was consumed at high levels, not moderate.
OP, presumably you are asking for both scientific as well as a personal level of comfort regarding the consumption of soy. Part of your answer has to do with your race. Certain racial communites have longevity of soy in their diet and therefore have acclamation (ex. Japanese men). Western, black, white men have little such acclamation. This can make a difference.
posted by Kruger5 at 5:47 PM on May 31, 2013
1. Medical conclusions are often revised given new, better research and methods. At times, to opposite conclusions.
2. There are verified cases of men legitimately suffering from breast growth and related hormonal changes. Note, soy was consumed at high levels, not moderate.
OP, presumably you are asking for both scientific as well as a personal level of comfort regarding the consumption of soy. Part of your answer has to do with your race. Certain racial communites have longevity of soy in their diet and therefore have acclamation (ex. Japanese men). Western, black, white men have little such acclamation. This can make a difference.
posted by Kruger5 at 5:47 PM on May 31, 2013
This is anecdotal, not scientific, FWIW. When I was pregnant and reading various materials on unmedicated childbirth, breastfeeding, attachment parenting, etc., I read a number of things about The Farm, a vegan commune in Tennessee (don't know if it's still around). The diet there was heavily soy-based. The men there seemed to father an average of 4 children (some couples had many more), all conceived after they and their wives had been living there and eating the soy-based diet for a significant period of time. The children were weaned from breast to the soy-based diet by toddlerhood. No apparent effect on fertility in either gender, and no evidence that I could find mentioned of any hormonal abnormalities in men, women, or children.
My brother consumes soy daily (not huge amounts), and has no abnormalities (other than his oddballness, which he was born with). He is Western and white.
posted by RRgal at 6:08 PM on May 31, 2013
My brother consumes soy daily (not huge amounts), and has no abnormalities (other than his oddballness, which he was born with). He is Western and white.
posted by RRgal at 6:08 PM on May 31, 2013
The feminization issue sounds like it isn't actually an issue. However, it might be worth considering the effects of high consumption of soy on brain aging. (That study is about tofu, not soy milk, but they're similar as far as both being non-fermented soy products.)
posted by Lexica at 6:30 PM on May 31, 2013 [2 favorites]
posted by Lexica at 6:30 PM on May 31, 2013 [2 favorites]
I always feel compelled to point out to soy-paranoids that most of Asia has been eating soy for nearly 3000 years yet Asia is not famous for its moobs. So just relax already.
posted by chairface at 6:41 PM on May 31, 2013 [8 favorites]
posted by chairface at 6:41 PM on May 31, 2013 [8 favorites]
When I was a lazy vegetarian, and getting *all* of my protein from soy, I definitely noticed symptoms that now, with benchmark experience of my body and mood at different, test-verified hormonal balances, I would identify as low-testosterone / high-estrogen.
That said if you're not consuming massive amounts of soy and if you're getting protein from other sources as well, I don't think you should worry at all.
posted by sixswitch at 7:39 PM on May 31, 2013
That said if you're not consuming massive amounts of soy and if you're getting protein from other sources as well, I don't think you should worry at all.
posted by sixswitch at 7:39 PM on May 31, 2013
There does seem to be a correlation between increased tofu consumption in Hawaii and an increase in dementia when elderly but (as far as I can remember, not a scientist, etc) the results of the Hawaii brain-ageing study aren't seen happening elsewhere, even in areas with much higher tofu consumption.
There might be a link between brain-ageing and aluminium in Hawaiian tofu rather than with the soy beans directly, or there might be some other factor involved.
A lot of the scare stories about soy are coming from one pro-dairy campaign group called WAPF who are very good at getting coverage in the press.
posted by BinaryApe at 2:02 AM on June 1, 2013 [1 favorite]
There might be a link between brain-ageing and aluminium in Hawaiian tofu rather than with the soy beans directly, or there might be some other factor involved.
A lot of the scare stories about soy are coming from one pro-dairy campaign group called WAPF who are very good at getting coverage in the press.
posted by BinaryApe at 2:02 AM on June 1, 2013 [1 favorite]
A lotta people have stories about what particular foodstuffs (in this case, soy) do to them.
As someone with an autoimmune disease connected to diet, I can tell you, dude, I trust all the studies, and none of the stories. Sheesh, I don't even really trust my own stories I tell myself about foods, and I am someone who has had great incentive to track my food & reactions, and made quite detailed attempts to do so. There are just way, way too many confounding factors, cognitive biases, and not too mention the placebo effect which will often be stronger than any other sideeffect.
Studies say you're fine unless you're eating at tonne of tofu, I wouldn't worry abot it.
posted by smoke at 2:40 AM on June 1, 2013 [2 favorites]
As someone with an autoimmune disease connected to diet, I can tell you, dude, I trust all the studies, and none of the stories. Sheesh, I don't even really trust my own stories I tell myself about foods, and I am someone who has had great incentive to track my food & reactions, and made quite detailed attempts to do so. There are just way, way too many confounding factors, cognitive biases, and not too mention the placebo effect which will often be stronger than any other sideeffect.
Studies say you're fine unless you're eating at tonne of tofu, I wouldn't worry abot it.
posted by smoke at 2:40 AM on June 1, 2013 [2 favorites]
Several answers have expressed skepticism about medical research. It is true that such findings can evolve or be reversed over time. Howevere, I would point out that the studies I linked to are not just small preliminary studies - they are meta-analyses of the available literature that encompass numerous studies. If you want to get a sense of how solid the conclusions are, read the papers. Meta-analyses are not the be-all and end-all of scientific research but their conclusions do carry more weight, generally speaking.
posted by treehorn+bunny at 1:25 PM on June 1, 2013 [2 favorites]
posted by treehorn+bunny at 1:25 PM on June 1, 2013 [2 favorites]
I always feel compelled to point out to soy-paranoids that most of Asia has been eating soy for nearly 3000 years yet Asia is not famous for its moobs.
This.
"Certain racial communites have longevity of soy in their diet and therefore have acclamation (ex. Japanese men). Western, black, white men have little such acclamation. This can make a difference."
Is there any scientific evidence that acclimation to a soy diet has anything to do with its effects?
posted by pravit at 2:54 PM on June 1, 2013 [1 favorite]
This.
"Certain racial communites have longevity of soy in their diet and therefore have acclamation (ex. Japanese men). Western, black, white men have little such acclamation. This can make a difference."
Is there any scientific evidence that acclimation to a soy diet has anything to do with its effects?
posted by pravit at 2:54 PM on June 1, 2013 [1 favorite]
This thread is closed to new comments.
1. Hamilton-Reeves JM, Vazquez G, Duval SJ, et al. Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis. Fertil Steril 2010;94:997-1007.
2. Messina M. Soybean isoflavone exposure does not have feminizing effects on men: a critical examination of the clinical evidence. Fertil Steril 2010;93:2095-104. (see attached PDF)
posted by treehorn+bunny at 4:52 PM on May 31, 2013 [7 favorites]