Ascertaining the bad guys; or is it a good guy?: SOY

SO, I have finally gotten around to publishing this article on soy. While nobody probably knew it was coming, I’ve gotta say that soy consumption and its physiological effects have been subjects weighing heavily on my mind for some time. Soy has always seemed to me to be a kind of iffy foodstuff. Still, I went into doing this article in an attempt to be as unbiased as possible. Besides a “for what it’s worth,” I’m not sure what such an assertion means to you, but I definitely wanted to learn of any and all healthful attributes of soy and went in with hope that something that’s so prevalent in our current food supply might be fine and dandy.

On one hand, there’re many opponents of soy who point out the crop’s big-business ties, high percentage of GMO soy amongst the aggregate crop, and estrogen-inducing qualities. On the other hand, we have folks who would say that the meat industry has an equal amount of plants (anti-pun not intended) who have made soy out to be bad to boost sales of their possibly-unsustainable fare. These folks, the vegan ranks among them, talk of the high, almost complete, protein availability of the crop, as well as its potential to combat certain cancers and heart disease.

So, who is right? Coming into this, I was just as confused as anyone; but those who know me best know I have avoided soy for a long time because it just didn’t sit well with me, despite claims from either side. Now, after much research, I am glad to say I have come to a conclusion and also glad to share my findings with you. As with everything discussed by me, it is going to be long-winded. So, if you can’t stand suspense, scroll on down. Sure takes the fun out of the journey of discovery I hope you’ll take with me, though! Anyhow, onward!

There ain’t no good guys, there ain’t no bad guys…


As I’m finding with mostly everything food-related, there are certain goods and bads in the ingestion of soy. I wanted to make this more simple for myself and just kind of list the pros and cons of eating soy, but I found the line is a bit too blurred in this case.

Most mentions of the “good” of soy lie in its aformentioned cancer and heart disease-fighting properties. So, what’s the scoop on that? Lots, really; it should first be said and noted that any disease combating abilities of soy are not just because of the soybean itself, but mostly because of its inherent (and inherently estrogenic) isoflavones (with a compound called genistein being the most potent) and a peptide called lunasin. Again, I can’t really talk in polar circumstances, so I’m simultaneously going to tackle the goods and bads of isoflavones and lunasin below; hope it isn’t too confusing!

Heart health

Most studies linking soy ingestion to heart health show its cholesterol-lowering effects. Compared with casein protein (from milk), soy protein was found to lower intestinal cholesterol absorption and increase the fecal loss of steroids. Genistein, the isoflavone I mentioned above, was the guy found to be directly responsible for this, lowering both HDL and LDL cholesterol, as a group which received soy with genistein extracted only saw beneficial readings in HDL cholesterol numbers. Again, there was a casein (milk) group, who showed negative effects on both HDL and LDL cholesterols, and a higher incidence of atherosclerosis.

However, I would like to stop and point out a few things in the face of this evidence. Firstly, I am unsure why in so many studies (including the much-vaunted China Study), the animal protein of choice is casein. As I’ve reported elsewhere, casein is a terrible substance for human consumption for its stopping of nutrient absorption and histamine release. Not that I’m some big meat advocate from Big Meat, but I think whey or fish would most certainly be a better source of protein for a study. Next, I have to say that soy’s- and in particular, genistein’s- benefits do not seem to be across-the-board. Other studies have found that genistein had little effect on blood lipid profiles and that cholesterol-lowering effects are higher in men. The cited study does, however, state that women who took a large amount of isoflavones were prone to gaining bone mass in the spine, however, which might be promising in the face of osteoporosis. Still, and on the subject of cholesterol and blood-pressure lowering, the effects of soy seem to be highly variable amongst individuals; some folks respond well, and others simply have little or no change in cholesterol numbers. This may be due to the fact that soy isoflavones are not always readily absorbed through the intestines and might not show up in certain individuals’ blood stream to garner the cholesterol-lowering effects. Also, along with the unpredictable variance in cholesterol numbers, those who ate 40g soy daily over a 3-month period were shown to have lowered endothelial (artery cell wall) function, which could assist as a precursor to atherosclerosis.


“Luna sin” means “without moon” in Spanish; so, this picture here’s a funny joke. Laugh, or else. By the way, “luna sin” actually means “moon without,” but that doesn’t fit my joke. Peace!


I feel like I’m skipping around a lot, but I’d like to go ahead and skip around some more and get on the subject of Lunasin, the healthful peptide I mentioned earlier.

For many years, a substance called the “Bowman-Birk Inhibitor” (presumably named for its discoverers?) was thought to be the source of some of the cancer prohibitive properties of soy, but it was recently discovered that this inhibitor was only a protective shell for the real hero: lunasin. From the studies I’ve read, lunasin seems to be a promising substance in the realm of cancer research; but here comes another “however:” There are a few issues with lunasin in soy that I must express. Firstly, the bioavailability (percentage that one can reasonably expect to absorb on a consistent basis) is only about 4.5% in healthy men after the consumption of 50 whole grams of soy protein. Also, different soy products show variations of the amount of lunasin, if any, ingested; in order of most to least-containing lunasin soytypes: soy hydrolyzate, soy protein isolate, soy protein concentrate, soy flour & flakes, and finally isoflavone-enriched products, which were found to contain no lunasin. So, you heard it here first: A label touting that something has “added isoflavones” is meaningless and simply a selling point.

Also bad for the soy camp: Since the initial finding of lunasin in soy, it has gone on to be found in meaningful amounts in barley, wheat, and amaranth, as well as being cloned and synthetically created, finding novel usages by that vehicle. I’ll finish this lil’ section up by pointing out that lunasin, while a useful substance to help in the prevention of cancer, has no effect on pre-existing cancer. Just a little informational aside to anyone who is diagnosed and thinks soy, or by extension wheat or barley, is gonna “save the day.” Sorry!

More on isoflavones and the dreaded estrogenic effects

Okay, so far this is sounding like a diatribe; I’m really not trying to come off as negatively biased, but the studies are speaking for me. Let’s try for something positive, here:

I have found evidence that soy isoflavones/phytoestrogens improved hot flash symptoms in up to 40% of women over a 12-week period.

I kind of feel bad in saying that’s kind of where the good news for pro-soy folks ends, however. I mentioned genistein, before; along with lunasin, it has been studied as a preventative for disease and as I mentioned, has been cited as a source for lowering cholesterol numbers. It is a mildly estrogenic compound, called a phytoestrogen, and thus has raised many red flags for the soy-averse. I’d like to quell said “soy-averse” people’s fears, here, but I’m afraid the studies don’t back up such lulling.

Most, if not all, of genistein’s cancer-fighting properties come from its status as an estrogenic compound; that is, it interacts with estrogen receptors and the like which seem to have close relationships with cancer growth. What seems to be the mechanism, oddly, is the ability of these phytoestrogens to be anti-estrogenic, decreasing the estrogen reception concentration of our cells and thus the normal growth that might occur (whether it be natural growth or a cancerous tumor growth) in the absence of such inhibition. It’s sort of a frightening concept to me; that in a healthy non-cancerous individual, this phytoestrogen would be limiting growth. To that end, genistein actually competes with the natural estrogens in your body, with prolonged exposure actually dampening the estrogen receptor activities of your cells. Again, as some cancerous cells are prone to needing a lot of estrogen, this could be a good thing. However, and in the last study I cited, (and this is highly weird) genistein in moderate amounts acts as a growth helper for estrogen-dependent breast cancer cells, but as a deterrent of their growth at very high amounts in the body. As I’ve already stated, having high amounts in the body for prolonged periods gives us estrogen resistance in our cells; so, to me genistein seems like a double-edged sword that might only be appropriate used as a high-dose medicine for a short time to repel cancer, not as a daily food where moderate amounts might actually cause cancer. The difference in the phytoestrogen equol (synthesized from genistein) to its natural estrogen colleague estradiol is that apparently the latter (as with all natural estrogens) stimulates DNA synthesis where equol does so very weakly or not at all, which leads to its more anti-estrogenic (cell stunting) properties.

Still, it seems genistein is a factor in the production and/or stimulation of cells called TGF Beta 1s, which help with cell growth, and are apparently inversely related to atherosclerosis in that TGF beta 1s are present in a magnitude around 5 times more in healthy subjects than those with atherosclerosis. They also have shown promise in assisting patients with a rare disorder called Hereditary Hemorrhagic Telangiectasi, who often have terrible nosebleeds (Korzenik JR, Barnes S, White RI Jr., 1998). I just like to pepper in a few potential positives here and there, y’know!

Let’s talk about sex, ba-by~

“Yo SOY él/ella.” The jokes just keep a’rollin’.

So, speaking of estrogens: The big deal for most people, especially men, is the effect of phytoestrogens on sperm count and fertility and the like. Worry not, I looked into it and MORE.

The effects of soy on men, at least in regard to fertility and testosterone, are mixed; one study found that the typical amount of soy isoflavones consumed by most east Asian men (40mg) was not enough to exert any ill effects (volume, movement, fertility) on the semen of healthy young men. However, another study found that upping the dose to 70+ mg a day does have slight adverse effects on biologically-active sex hormones (lowered testosterone to estrogen ratios) but also with that carried a potential benefit against prostate cancer (which is apparently stimulated with high testosterone and low estrogen), which is less-often seen amongst asian populations. Also, I guess one would have to eat about twice as much as normal; and that might be more damaging from the oxidative stress from high caloric intake than any ill effect on testosterone. There are somewhat alarming studies done on animals which relate isoflavone intake to infertility; here with sheep (that were actually grazing on clover, not soy, and had adverse effects to fertility due to the isoflavones/equol in that plant), and here with cheetahs who were fed high amounts of genistein-containing soy, and had breeding and liver problems. Still, the human studies don’t seem to show these problems, though the research on humans so far is sadly negligible. I guess take the animal studies with a grain of salt.

Of more worry to me than the lowered testosterone/fertility issue, again, is the issue of the effects of phytoestrogens and another big problem with soy isoflavones in the body: their penchant to be goitrogenic.

What does that mean? Well, if you’re not familiar with goiter, it’s a sick-looking dysfunction of the thyroid which causes a large bulge to develop in your neck (I’ll leave you to image search for that one). There are numerous older studies which link goiter in infants to soy formula consumption, but the practice of enriching soy infant formulas with iodine in the 1960s seemingly cured all that. In one case of a baby with hypothyroidism, however, iodine supplementation was not enough. “One case,” you might repeat skeptically, but another study confirmed that teenagers fed soy formula as infants had a much-higher incidence level of thyroid problems when compared to their breastmilk-fed siblings and counterparts (31% vs. 13%). On the subject of infants: Studies show infants fed a daily regimen of soy-containing formulas have isoflavone exposure levels from 6-11 times what adults receive, comparing body weights. The circulating concentrations of isoflavones in the infants fed soy formulas were up to 22,000 times higher than normal blood estrogen concentrations, which may be sufficient to exert adverse biological effects. Breast milk and cow milk isoflavones were barely detectable. What about healthy adults? Well, a study of 37 normally healthy subjects (those who had never goiters or serum antithyroid antibodies) showed that in doses of 30g of soy a day for 3 months, half of the group (of folks taking for 3 months; 17 total were in this group) experienced malaise, constipation, and, at worst, goiter, which seemed to have reversed itself after 1 month of cessation of soy intake. The study authors warned against soy intake in older (61+) adults. In the interest of “jumping around” again, but still staying on the subject of the elderly, this study found that amongst individuals eating various amount of tofu and studied for a period of around 30 years, those who ate the most had brain atrophy events, resulting in cognitive disabilies including Alzheimer’s, with reduced incidence in those who consumed less tofu. ANYWAY…

Other effects on women

At least one study confirms that a high soy intake reduces the chances of contracting breast cancer, at least in Asian women; those who had high intakes their entire life into adulthood showed the least incidence, followed by those with varying intakes, and last with those in the low-intake category. The problem with we westerners in taking this in (including perhaps those of Asian descent who have lived their entire lives on a western diet) is that the results for western women fed high-soy diets have been insignificant in terms of prevention of breast cancer. That and the aformentioned worry (and seeming requirement) that a high soy intake is necessary and a physiological amount damaging, and that high soy intakes lead to estrogen resistance in cells and…well. Excessive amounts of estrogen in general seem to cause detrimental effects to developing fetuses and the like; this study in rats compared genistein (in an estrogenic dose of 50 mg/kg/day) to diethylstilbestrol, a synthetic estrogen, and found 35% and 31% case incidences of adenocarcinoma, respectively.

Jumping around again (but slightly on that thought) I found another interesting study that shows that the synthesis of equol (the phytoestrogen made from consuming genistein) can be lowered in high soy diets if you eat a high-fat diet, as well. However, this seems counter-productive in that the cancer-fighting effects of high genistein intake are negated, and you’d take on so many more calories from consuming the fats. Add to that the fact that the fats may inhibit equol’s synthesis to physiological levels (again, the minimum amount to illicit a bodily response; in this case, a potential cancer response) and you just can’t seem to win for losing with this stuff!

The estrogen-inducing effects of genistein have also been shown to cause lower birth weights to rat pups whose mothers were fed high amounts of the substance, with the offspring having weakened appetites. This is particularly interesting in the female offspring, who were more likely to gorge on salt, with female rats consuming 90% more than controls (68% more overall, meaning that males also gorged). Again, this is a rat model, but its implications on humans could be meaningful; sodium is often blamed for blood pressure problems (though I’m not certain I agree with that) and a higher incidence of body fat. Back to HU-MON women, it seems that women consuming 60g soy daily for one month have both delayed and lengthened menstrual cycles. That’s cause for alarm to me, though I’m sure it would be much worse for the confused woman experiencing it.

More claims from the opposition

I suppose other things to worry about, so says such poorly-sourced “doctors” like Joseph Mercola, are the dangers of trypsin inhibitors in soy and the supposed adverse effects of unfermented soy. I’d like to explore these two claims, a bit.

First, trypsin inhibitors: What are they? Well, basically they’re a miracle of evolution. In animals, we mostly see the change in outward form in some way over time which detracts or confuses predators i.e. the camouflaging abilities of chameleons or certain fish. In the plant kingdom, trypsin inhibitors do the same thing in a more microcellular way. Basically, plants evolve to make themselves less nutritionally desirable to certain predators so that they might stop gobbling them up. Trypsin inhibitors are part of this plan; they attempt (very well, usually) to stop the absorption of whatever beneficial nutrient they contain from being utilized by the predator that eats them (I suppose in the “plant hope?” that said predator will discontinue consuming). It’s a pretty novel concept, in my view, and has even been found being used by animals (in this case, the egg of a certain bird). Despite what people like Mercola might have you believe, soy is not the only plant food to contain trypsin inhibitors. Lima beans, for example, contain roughly 2 times the amount of trypsin inhibitors that are found in soy. I guess in his defense, it is more reasonable to assert the dangers of the inhibitors in soy since soy is so prevalent in food products nowadays where limas are not. It’s also a strange wonder what effects these inhibitors might be having; in one study, when soy was added to a nutritionally-complete liquid formula at 20 g, it increased absorption rates of copper, iron, zinc, and magnesium. However, as it was increased, finally to 40 g/day, the absorption surpluses shrank to deficits of said minerals.

Another “inhibitor” of note in soy is a type called a “protease inhibitor.” Protease inhibitors stop viruses from replicating. Protease inhibitors in soy only seem to inhibit carcinogenesis in the initial promotion and not during the tumor or radiation states (sounds a lot like lunasin, mentioned before), but I suppose this could be a good preventative measure.

Anyway, onward to the whole fermented vs. unfermented soy debate: I suppose Dr. Mercola is referring to the fact that unfermented soy is less-desirable since it has all the isoflavones intact and fermented soy (like what you find in tempeh and soy sauce) has negligible amounts. Well, in this case I might even have to burst the staunch Dr. Mercola’s bubble: Fermentation of soy seems to decrease isoflavone content of soy food products as he said, but increase bioavailability of remaining isoflavones as their presence in urine becomes increased. What does this mean, exactly? Hard to say, but if you follow that a physiological amount of isoflavones may cause cancer and that urinary excretion of equol denotes bioavailability, it might be best to come to the conclusion to simply stay away from either variety (fermented or unfermented).

For you bodybuilders, out there:

Many protein supplements contain protein derived from soy, so let’s take a look at what it does for protein synthesis i.e. muscle gain:

In a study where subjects were given different types of protein supplements and the synthesis of protein and growth of muscle was measured at rest and after strenuous exercise, soy was found to be far inferior to whey protein (though soy was found to be superior to the sickly casein protein, proving that animal proteins are not always preferable just because of their amino acid content).

Now, I’m no advocate of the whole protein powder or supplements craze. I think for the money one is shelling out for whey, for example, he or she could get a cheaper and better protein meal out of a nice fatty fish like salmon; however, undenatured whey protein has been shown to have very promising effects on glutathione levels in the body, doing everything from almost erasing joint pain from the elderly to, perhaps, cancer prevention. I have an article coming up on that, so I’ll save it, but the basic point I’m making is that soy, with its above-mentioned nutrient-blocking and lower protein synthesis dilemmas should not be seen as the go-to protein for bodybuilders. Most items containing it, protein bars and shakes, are pretty much chemical-laden candies anyway, and should be avoided for all the odd preservatives as much, if not more, as for the soy they contain.

“Heart healthy” Margarines

Finally, I’d like to touch on the subject of these soy-rich so-called “heart healthy” margarines. You may think this is out of the scope of this arti-cool, but you’re wrong (Dead wrong). Cool jokes aside, I’ve talked to at least a few friends (one of which was diagnosed with bad cholesterol/high blood lipids) who thought it was okay to use these types of margarines due to the fact they didn’t contain any cholesterol and things of that like.

Unfortunately, things are not so clear-cut when it comes to “bad” and “good” fats (I’ve written in extensive detail about that.). Further, aside from the mass confusion of people on how cholesterol does and doesn’t work in the body, there is an equal mass ignorance of the very existence of what are called “phytosterols;” which are cholesterol-like molecules found in plants, and specifically, plant fats/oils. There’s even a disorder similar to hypercholesterolemia called “Phytosterolemia” which, though rare, shows that superfluous plant sterols can have highly adverse effects to our systems.

When one takes into account that these margarines usually have a lot of plant sterols, a good amount of them soy, the “heart healthiness” factor begins to come into question. Not because of the flawed idea that cholesterol or phytosterols are bad for you (please see above mentioned post on fat), but because 1) The omega 6 to 3 ratio of many polyunsaturated fats like soy and especially sunflower/safflower is staggering in favor of omega 6s, which cause arachidonic acid build-up, thus inflammation, thus detrimental effects that can lead to atherosclerosis, and 2) the amount of phytosterols one could get in these margarines is far more than one could easily get from food; for example, one would have to drink about a liter of soybean oil to get the equivalent amount of plant sterols in a tablespoon of margarine.

Again, I suppose this is a rant on the mistaken “goodness” of polyunsaturates rather than on soy itself, and perhaps it doesn’t belong in the article, but I hope it has opened your eyes.


Welp, pals; this has been some mash-up of info on soy. I hope it wasn’t too confusing or that it seemed biased either way. I really tried to give soy a chance here, but all-in-all it seems like a no-go. Let’s review the big points:

Soy has novel cancer-fighting and heart-helping properties, but the ends don’t justify the means. From an optimum health point of view, components of soy go from promising (lunasin) to scary (genistein). Genistein’s disease-pouncing and growth factor-creating effects also come with the added danger of estrogen resistance; and while lunasin seems to offer some hope for understanding and combating cancers, the peptide can also be found in more “western” crops like wheat. So many people eat soy because they believe it more healthy than meats, but endrocrine and thyroid dysfunction paired with the fact that one can get all the essential amino acids from other plant sources (chia seeds, anyone?) if he or she doesn’t want to eat meat, and even those with a vegan diet should be convinced to stay away. Plus, more emphasis should be put on lowering caloric intake per meal and eating simple foods with high nutritional value (this can be done in a tasty way; potatoes, fruits, et cetera- mmm mmm!) than trying to eat a faux version of one’s favorite meat which is, more often than not, highly processed, preservative-laden and far from simple. (I doubt most people are eating plain soybeans)

The “unfermented vs. fermented” debate is moot. As evidenced, even the “safe” unfermented soy can add dangerous levels of isoflavones into one’s system, with enough consumption. The amount of isoflavones lost in the fermenting process is unimportant, as the remaining isoflavones become more bioavailable, thus affecting the body in physiological amounts, thus (as explained earlier) increasing cancer risk.

Ancestral eating habits do seem to make a difference. At least where soy is concerned. We Westerners, no matter how hip, trendy, and health-conscious we try to be, did not have ancestors who gouged on soy. I hate bringing up the “ancestral” card, because there are a lot of complicated factors involved and people (Paleo annoyances. Ahem.) try to use it as an over-simplified justification of their sometimes-ridiculous diets. However, as you’ve seen, the studies are there. Long-time cultivators of the soybean, i.e. East Asians, seem to be much more susceptible to any beneficial effect soybeans have on health.

94% of the US crop of soybeans is genetically-modified. While one could probably find organic (and thus non-GMO) soybeans, with the factors above on her brain, why would she? I have no official numbers for the rest of the world, but already by 2007 over half of the soybean crop worldwide was genetically-modified. For more on that, feel free to peruse my arti-cool on GMO crops.

I could go on, but really: need I? The point has been made, and that is that avoiding soy is the unavoidable path of intelligence. With so many other nutritive food stuffs and protein sources, there is no need to ingest this junk. With the light of this article, I hope you can ignore the health claims you see on labels of soy products, and choose to eat simple (but tasty) healthful foods.

Soybeans might not be good to eat, but here’s this: