Soya-noia could Destroy-ya!

From Mark Sisson's Weekend Link Love this past weekend comes this:  Soy protein present in egg yolks and chicken tissues.  Ruh roh!!  Mark writes:
It’s confirmed: meat and eggs from soy-fed chickens contain soy isoflavones. The title of the article – “Soy protein present in egg yolks and chicken tissues” – isn’t quite accurate, but soy isoflavones are often phytoestrogens and thus somewhat concerning.
Boys are reaching puberty younger than ever before, a new study shows, but “it’s unclear why.” Perhaps the phytoestrogens from soy-fed chicken products are involved?

I'm sorry but this sort of thing really grates on me leading to unnecessary dietary angst.     It is one thing to avoid things where soy is directly added or direct soy products such as soy milk, tofu soy protein in processed foods, and even the beans themselves.  If that's an issue for you, that's between you and your body.  It's also fine by me to avoid commercially raised chickens/eggs for various reasons from questioning of the treatment of the chickens, to sustainability, to the use of unnatural diets, antibiotics, and hormones.  Again, to each their own.

I just don't think it's helpful to needlessly demonize two of the most economical protein sources out there: eggs and chicken.  Doing so is, frankly, irresponsible!  Dare I say especially so for someone who purportedly is trying to help people improve their health while making a living doing so.  Or is it only those who can afford and have access to pricey non-commercial alternatives that we care about?  Remember too, that Mark's Sample Menu cited eating "chicken (with the skin on!)" as a "regular" for dinner, and thus leftovers often topping off his Big Ass Salad.  Do we really need to burden those struggling to make ends meet that at least opt to buy chicken and cook it at home with more stressors?  Heck, I am far from struggling and I just, gasp!, purchased a butt ton (well a whopping $10 worth) of chicken legs from Stew Leonards for $0.69/lb.  I am not worried over this chicken harming my health, and if I had young boys, I'd not worry in the least feeding it to them either.  I hope after reading this blog post, any who might be wary and worried, will no longer be either.

Organic Soy-free Eggs 1 dozen Carton
First off, let's look past the past the scare-mongering headline at the link.  First I note it's to Health Impact News Daily, subtitled:  News that Impacts Your Health that Other Media Sources May Censor! Oooooohhhhhh.  Such claims have me switching to the browser in which I've installed my new AMH (Anti-Mercolaesque Hyperbole) plug-in.  Who puts out Health Impact News Daily?   Tropical Traditions, an outfit dedicated to over-hyping the miracles of the coconut.  Atop this "news" article we see this is a cleverly disguised advertisement for their soy-free eggs.   These eggs come from chickens:
"raised by family farmers [that] eat a coconut-based soy-free feed mixture that is certified organic, with no genetically modified grains (no GMOs!). 
Yeah, because as we all know, soy may well be an unnatural food for the chicken, but chickens have a long evolutionary history of consuming coconuts.  C'mon!!  From the egg link:
Almost all commercial eggs, including those that are organic or marketed as "Omega 3" eggs, are from chickens fed high concentrations of soy. So if eggs are a part of your diet today, so is soy protein, whether you realize it or not. 
Now when one thinks of soy proteins, as Mark rightly points out, isoflavones are not really what comes to mind.  The Tropical Traditions use of this renders this "health news" scientifically bankrupt from the get-go.  

Alright, so maybe they are just suffering from Mercolaperbole, but we shouldn't disregard the good underlying science out of hand because of this.  These cases, however, tend to counter the old adage about smoke and fire.

But, I look into it a bit because I know a thing or two about soy isoflavone doses, because I took max strength Estroven when I went through menopause.  And this soya-noia almost kept me from even trying this inexpensive (especially getting it from Costco)  remedy.  Either the isoflavones or something else in there, or the synergistic mix really did help me, particularly with my most severe symptom of night sweats.  What is the concentration in this max strength Estroven?  A "mere" eighty milligrams, 80 mg.  Let's keep that number in mind.  For a 100 to 200 lb woman, this works out to a dose of 0.8 to 0.4 mg/lb/day.

So let's look at the HIND cited study:  QUANTIFICATION OF SOY ISOFLAVONES IN COMMERCIAL EGGS AND THEIR TRANSFER FROM POULTRY FEED INTO EGGS AND TISSUES.  First, they looked at the soy isoflavone  (from hereout, SI) content of commercial eggs.  The graph at right shows their results (you can click to view full size).  

It is very important to note that "isoflavones were found in the egg yolk of all commercial egg samples analyzed in concentrations ranging from 33 to 120 μg of isoflavones/ 100g of egg yolk."  Note:  MICROgrams of SI per 100g of egg yolk, where a large egg yolk is 17g.  Let's round up to 20g per yolk, and use the maximum SI content of commercial eggs and do the calculation: 

In commercial eggs currently available at your run-of-the-mill, plebeian-frequented, addict-patronized grocery store, soy isoflavone content is at most 0.024 milligrams per large egg yolk.  
(I'm presuming there wasn't much to be alarmed over in the whites).  Let's put that in context with maximum strength Estroven at 80 mg, you'd have to consume 3333 commercial eggs of Brand 8.  Even presuming anything would happen at 1/1000th of that dose, we're still talking 3 eggs to reach just that!

A little more math for context.  
  • On the "In" Side:  In the study (thesis) they then fed chickens for 28 days, regular feed, soy enhanced diet and a SI-enhanced feed that included 500 mg SI/100g.  I Googled a bit and found that your average American egg-layer weighs around 6 lbs and consumes around 100g feed per day.  Therefore, in order to produce the "alarming" levels in this study, they fed these chickens over 6X the dose of concentrated SI that menopausal women might consume as a supplement (max strength!).  On a pound for pound basis?  These chickens received over 80 mg/lb/day ... compared with a 150 lb menopausal woman taking maximum strength Estroven getting around 0.5 mg/lb/day.  
  • On the "Out" Side:  For now just meaning the SI content of eggs produced, they found roughly 1000 micrograms = 1 milligram (1 mg) per 100g egg yolk.  So, this is up from 33 to 120 μg per 100g egg yolk.
Thus, expose egg-laying chickens to 160X the dose of soy isoflavones a menopausal woman might take in a supplement and their eggs will contain, in the yolk, a level roughly 10X the maximum level currently present in commercially available eggs.  This thesis did indeed demonstrate that high levels of SI in the diet can impact egg/tissue levels.   Anyone wanna go in on my Menovum (copyright, trademark and all those dibbs laid here!) egg project?!  LOL.  Beyond that, however, was this at all significant in the global scheme of things?  No.

Let's look at eggs vs. chicken muscle -- aka "chicken".  In the mega SI dosed chix, the eggs were found to have about 1000 μg/100g yolk while the muscle was found to have roughly one-tenth that, at 100 μg/100g.  For those not in the metric groove, if you ate one full pound of Estrovenofied chicken meat, you would get 450 μg SI or less than half a milligram "exposure".  But -- investors, are you hearing me??!! -- you can achieve that with just 2 jumbo Menovums!!!  Whoa boy, I'm probably giving some opportunistic shyster ideas here :(:(  Here's a better idea, I suppose, foie gras from these chix!  A whopping just over 7000 μg = 7 mg per 100g liver was found in those chickens.  Woo hoo!! Stop me before I kick off the next scam (folks omega-3 eggs are a scam, just check the numbers, just eat the fish oil yourself!).

But ... but ... what about cumulative effects?   There appear to be none ... at least not on what we consider a truly long term.  In the study they fed the chickens this diet for 28 days, the isoflavones peaked at around 10 days.  Further, isoflavones in eggs of the high SI chickens became undetectable after 10 days of switching the chix to a soy-free diet.   This would argue strongly against any claims that consuming these eggs or chicken meat may lead to an accumulation of SI to deleterious effect.

OK, now time to take Mark Sisson to task here for his rank speculation about the role of soy chicken feed as possible culprit in early puberty in boys.  There's a saying that with great power comes great responsibility.  I'm told this is biblical in origin, but I think one can be of any religious persuasion or none at all and agree with that adage.  Through the sheer volume of his website traffic, Sisson wields great influence and is about as powerful a figurehead in the community as any.  With that power does come great responsibility, whether he wants it or not, and such episodes of flippant speculation are not helpful here.

One doesn't even need to be scientific about this, just apply some common sense.  Whole egg consumption is down, and while chicken consumption is up (quite a lot), a goodly portion of that is the dreaded skinless/boneless chicken breast and fast food mangle-ations thereof.  Trace isoflavones in the diets of boys these days?  Highly unlikely.  About as unlikely as a chicken eating coconut.  


bentleyj74 said…
Say! Maybe having the soy process through the chickens first is beneficial. Maybe it allows the consumption of the "yay for soy" components at lower levels minus the "nay for soy" components. Hasn't the argument about the role of soy in oh so many healthy cultures been that theirs was fermented and at much lower total loads?

Missed my calling as a spin doctor
Aaron said…
"For those not in the metric groove, if you ate one full pound of Estrovenofied chicken meat, you would get 450 μg SI or less than half a gram "exposure"."

Isn't a microgram one millionth (1/1000000) of a gram? Half a gram would be 500,000 μg, right?
CarbSane said…
Thanks for catching my type Aaron ... fixed! Yes 450 micro = 0.45 milli
CarbSane said…
Oops, meant typo ... But since I'm posting again, my mention of metric was to put the dose per 100g into poundage.
Puddleg said…
Soy isoflavones are found in all sorts of foods that are very natural for wild chickens to eat; they are fairly prevalent in legumes.
I have a horrible allergy to soy, so I would hate to eat these eggs, but I can take soy isoflavone supplements (which have a good profile for being protective against hepatic fibrosis) with no obvious ill effects. Not that I do this often, but I've always found them to be inert whereas unfermented soy causes a condition that could be misdiagnosed as leprosy within minutes.
So I think the hype about isoflavones is just that. You don't want massive doses, like in soy milk, but it's a normal part of the food supply for anyone eating beans, dhal, and sprouts.
CarbSane said…
The "news" article was hyperbole -- there was no "soy" in the eggs, just minute amounts of isoflavones.
Unknown said…
I'm not sure how I feel about this, in the NYT article they describe measuring puberty by "growth in the size of the testicles," where they measured boys' testicles with some kind of device and also took note of pubic hair, and from there we take a gigantic leap to some kind of sciency thing that is contained in the yolk of chickens who are fed soy. So is Primal in favor of large testicles or smaller testicles? And if you are a parent of a child do you even take note of testicular volume? I would think that immense testicular volume is Primal as all get out and a Primal parent would brag about how their son needs a wheel barrel to carry them, but in any case I doubt that a big topic at is "My son's balls are too big," how did we even get on the subject of testicular volume in adolescent boys, now we are probably all on some kind of watch list. In any case the real test for puberty in boys is the "Spanking The Monkey" test, when eating eggs from chickens who are fed soy makes a difference in Spanking The Monkey then we may have something to talk about, until then to me it seems like Six Degrees Of Separation, you've got weird doctors measuring kids' testicles and then you have chickens getting fed soy products, how do these even connect?
Steven Hamley said…
This document from the USDA suggests isoflavones are in many foods and the amount in commercial eggs is pretty low. The concern with soy should not be that it simply has isoflavones, but the amount it has, which is roughly 100-1000 times higher than most other foods.
Sometimes one can see how the over obsessing with the minutiae of dietary details can actually cause the confusion and obsession over dietary choice often seen in comments on food blogs, unless a significant part of your daily intake is soy based why is this an issue? Another case of a certain type of food being demonised , now in the paleosphere foods possess magical properties and we have the likes of bulletproof coffee free of fungal toxins, highly specified supplements and pseudoscience everywhere. Soy products are demonised by the Weston A Price foundation who seem to be gaining influence and credibility in the paleosphere because it is in their interest to promote raw milk, an antithesis to soy milk , most of the paleo gurus seem to be of a certain ideological mindset that provides the drive behind this so called lifestyle .
blogblog said…
This comment has been removed by the author.
blogblog said…
My first job as a food scientist was in the egg industry. One of the first things I discovered that eggs are highly variable depending on the chickens' diet. I saw blood red yolks and white yolks. I even saw yolks that turned pink when cooked (due to the chickens eating some sort of weed.)
blogblog said…
Paleo is a religion that relies on spurious science.

Contrary to the Weston Price dogma liquid milk was rarely consumed in Western countries until the 20th century. Milk was invariably made into cheese or butter. The whey and skim milk was used as pig food.
I have this image in my head of a flock of wild chickens gathering around a coconut and pecking the shit out of it. Maybe they should change the name from "coconut" to "chickenut".
CarbSane said…
I can see it now -- KFC switches to chickenut oil fried chicken!
CarbSane said…
Interestingly in some of the stuff I found on soy before I decided to try Estroven many of the claims made for coconut oil are seen for the isoflavones.

Hmmm, I see a marketing angle for my Menovums -- all the good stuff transferred to the egg (why would it go there if it wasn't good?) and none of the nasties. Thanks bentley!
CarbSane said…
Interesting document. I am open to the arguments against soy as staple direct food, but I'm also wary of controversies like this dominated by hyperbole and short on results. Even looking for studies on efficacy of isoflavones for menopause, the results are rather less than a home run with deliberate bolus dosing, but something in the Estroven definitely helped me.

I seem to have attracted some anti-WAPF spam with this post.
CarbSane said…
@bb: This melds with my memory and experiences growing up. Just as we Americans are always missing the govt encouraged intakes of fruits and veggies, so, too, in the 60's and 70's we weren't drinking enough milk. When you look back at nutrition guidelines (and they existed before 1980 folks, just not so overtly government centralized) the recommended milk intakes were quite large and I recall bugging my Mom about this. We didn't drink milk in our house, though it was used in recipes. The schools had the milk program we were strongly urged to participate in (I'm thinking if this were nowadays, it would be mandatory) to make sure we got at least 1c a day. When a food is pushed as a means of preventing deficiencies, and requires lots of pushing, it's usually a good sign that we are "underconsuming" that food. The wisdom of whether the food is good/bad/indifferent aside, I think such is indicative of historic/traditional consumption -- e.g. represents a change.

This community is famous for romanticizing the past in terms of food consumption. When Lustig brought up HFCS in formula I was surprised to learn how prevalent bottle feeding was in the 50's. My generation ate plenty of carbs in the 70's and we weren't fat. Stuff like that. Lately Fat Head has been talking about old cookbooks and such and the focus on meats. I have a 1950 cookbook I'm inclined to posting some citations from.
Unknown said…
Darn you and your logic and critical thinking. Can't anyone go on a rollicking dietary witch hunt without you coming along and spoiling all the fun? Shew.
Anonymous said…

'Current observational studies suggest notable associations between dietary intakes and pubertal timing beyond contributions to an energy imbalance: children with the highest intakes of vegetable protein or animal protein experience pubertal onset up to 7 months later or 7 months earlier, respectively. Furthermore, girls with high isoflavone intakes may experience the onset of breast development and peak height velocity approximately 7-8 months later. These effect sizes are on the order of those observed for potentially neuroactive steroid hormones. Thus, dietary patterns characterized by higher intakes of vegetable protein and isoflavones and lower intakes of animal protein may contribute to a lower risk of breast cancer or a lower total mortality.'

'A higher total and animal protein intake at 5-6 y was related to an earlier ATO. In the highest tertile of animal protein intake at 5-6 y, ATO occurred 0.6 y earlier than in the lowest [(mean, 95% CI) T1: 9.6, 9.4-9.9 vs. T2: 9.4, 9.1-9.7 vs. T3: 9.0, 8.7-9.3 y; P-trend = 0.003, adjusted for sex, total energy, breast-feeding, birth year, and paternal university degree]. Similar findings were seen for APHV (P-trend = 0.001) and the timing of menarche/voice break (P-trend = 0.02). Conversely, a higher vegetable protein intake at 3-4 and 5-6 y was related to later ATO, APHV, and menarche/voice break (P-trend = 0.02-0.04). These results suggest that animal and vegetable protein intake in mid-childhood might be differentially related to pubertal timing.'

ATO=pubertal growth spurt

blogblog said…
I once saw some baby bottles at a museum dating from the 1850s.
blogblog said…
Ironically wild chickens (jungle fowl) are dedicated low carbers. They eat mostly insects and leafy greens and avoid grains.
CarbSane said…
To channel the iconic NYC broadcaster Bob Grant, somebody's gotta say these things, it might as well be me! :D Welcome to the comments Kaleo! I do believe this is a first despite "knowing" each other for a bit.
Anonymous said…
Carbsane, just curious - how did you get your calcium in those days?
CarbSane said…
I presume you are asking about childhood? Well, we did consume a fair amount of dairy. Cheese was sometimes the "protein" at a meal (including cottage cheese) and yogurt was pretty big in our house. Greens were a biggie too. I never broke a bone despite battering my body with athletics and stunts as a kid, so I'm pretty sure I was AOK in this department.
CarbSane said…
Thanks for the excerpts with the links! Helps when I'm time constrained. So if anything primal would accelerate puberty vs. veggie protein. Or did I read that wrong?
Unknown said…
Girl. I've been stalking you for years. You have no idea.
blogblog said…
Bones are mostly made of protein not minerals. This fact seems to have completely eluded the medical profession. A lack of bone minerals makes bones SOFT not brittle.
Puddleg said…
Any pasture-fed ruminant that eats clover should have these isoflavones in its meat and milk, come to think of it.
Puddleg said…
I believe that soy milk was invented and first fed to babies during the Siege of Leningrad, due to lack of cows milk.
CarbSane said…
True about composition, but bone strength is more than just soft v. brittle. Good bone health is associated with turnover, and appropriate rates of resorption and formation. The seeming blinded focus on calcium is troubling, but it makes for a thriving supplement business ;-) When I had my bone density checked at one of those screenings (obviously not the most accurate, but ...) at Costco, it was sponsored by the Caltrate folks and they were selling the supps and handing out samples.

The medical profession is not near as dumb about this as one might think looking at the media-medical advice vis a vis calcium however. The Fosomax's and such target cell turnover.

Sure we need calcium for growing bones, but it would seem dietary requirements may well be overstated. Calcium deficiency? Likely other issues of undernourishment at play.
Anonymous said…
I read it that way, too!
dangph said…
"There's a saying that with great power comes great responsibility. I'm told this is biblical in origin"

No, the saying is from Spider-Man. It has also been attributed to Voltaire, but since no one seems to have his original quote in French, I'm skeptical that he ever said it.
Praxis Developers said…
Such a nice blog...i like it.