---
created_at: '2013-11-29T02:36:43.000Z'
title: Soy's Negative Effects (2009)
url: http://www.menshealth.com/nutrition/soys-negative-effects
author: 001sky
points: 52
story_text: ''
comment_text: 
num_comments: 46
story_id: 
story_title: 
story_url: 
parent_id: 
created_at_i: 1385692603
_tags:
- story
- author_001sky
- story_6817587
objectID: '6817587'

---
“Men aren’t supposed to have breasts,” he says today in a quiet Texas
drawl. “It was like my body was feminizing.”

A lean and wiry man, the breast development stood in stark contrast to
the rest of his body. But it was not Price's only symptom.

His beard growth had slowed, he’d lost hair from his arms, chest, and
legs, and he’d stopped waking up with morning erections.

“My sexual desire disappeared,” he says. “My penis—I won’t say it
atrophied, but it was so flaccid that it looked very small in comparison
with the way it used to be. Even my emotions changed.”

**Related: **[The Men’s Health Guide To Erectile Dysfunction: Everything
You Need to Know to Keep Your Penis Healthy For
Life](https://www.rodaleu.com/courses/the-mens-health-guide-to-erectile-dysfunction?utm_source=MensHealth&utm_medium=article&utm_campaign=soy's-negative-effects)

The first three doctors Price consulted diagnosed him with gynecomastia,
or the abnormal enlargement of the mammary glands in men.

Tests further revealed that estrogen levels in his bloodstream were
eight times higher than the normal limits for men, higher even than the
levels typically seen in healthy women. Price’s estrogen was so high, in
fact, that the doctors were at a loss to explain it. One physician
became so frustrated he eventually accused Price of secretly taking
estrogen.

“He thought I was a mental case,” says Price, still angry as he recalls
the experience.

Dispirited and in pain, he decided to try one more doctor, this time a
fellow military man.

**Related Video: **

He made an appointment with Lieutenant Colonel Jack E. Lewi, M.D., chief
of endocrinology at the San Antonio Military Medical Center. During that
first meeting, neither doctor nor patient had any inkling of just how
long and complex this medical mystery would prove to be.

 

Dr. Lewi initially checked for “usual suspect” lifestyle factors known
to trigger gynecomastia, from alcoholism to certain herbal ingredients,
like tea-tree oils and lavender. With those ruled out, Dr. Lewi was left
with a more dreaded suspect: an estrogen-secreting tumor.

Over the next few months, Dr. Lewi ran multiple tests, checking Price
for
[cancer](http://www.menshealth.com/health/cancer-second-most-common-man-killer)
of the testicles, adrenal glands, chest, and lungs.

The good news: When the final test came back negative, Price was in the
clear on all fronts. The not-so-good news: Dr. Lewi still had no clue
what was causing his patient’s hormones to go haywire. But he was
determined not to be the fourth doctor to leave James Price in limbo.

In the classes that Dr. Lewi teaches to medical students and residents,
he has long offered this advice: If you’re not finding the right
answers, you’re not asking the right questions.

Though he’d asked Price about his lifestyle and habits innumerable
times, he decided to go back once again, and this time to make his
questions as specific as possible.

**Related: **[Top Cancer Doc Gives 5 Lifestyle Strategies to Avoid
Cancer](http://www.menshealth.com/health/stay-cancer-free)

“I said, ‘Let’s go over your diet, meal by meal, and you tell me every
single thing you eat and drink.’ He said, ‘Sure, Dr. Lewi. I get up and
usually have some cereal.’ I said, ‘Do you put anything on it?’ He said
‘[Soy
milk](article.do?category=other.diseases.ailments&channel=health&conitem=43f999edbbbd201099edbbbd2010cfe793cd____).’”

Price explained that he’d developed [lactose
intolerance](http://www.menshealth.com/nutrition/you-might-be-lactose-intolerant)
in recent years and had switched to [soy
milk](article.do?category=other.diseases.ailments&channel=health&conitem=43f999edbbbd201099edbbbd2010cfe793cd____)
exclusively. It had, in fact, become one of his favorite drinks, a great
thirst quencher in the Texas heat.

 

Dr. Lewi suddenly felt his excitement building. He asked Price how much
soy milk, on average, he drank each day.

“He told me, ‘Probably about 3 quarts,’” recalls Dr. Lewi about the
moment that changed everything.

Over the past decade,
[soy](article.do?category=other.diseases.ailments&channel=health&conitem=43f999edbbbd201099edbbbd2010cfe793cd____)
foods and good health have become inextricably linked in the national
consciousness.

According to annual U.S. consumer attitude surveys by the United Soybean
Board, 85 percent of those polled in 2008 rated soy products as
“healthy,” a significant increase from the 59 percent who in 1997
thought this was the case. Many men, to be sure, are hard pressed to
explain why soy is supposed to be so healthy, but they take it on faith
that they should embrace the bean.

“It’s something you need to train yourself to like, you know, for the
health benefits," my friend Larry, a distance runner, opined recently.

“Tofu’s the modern equivalent of cod liver oil,” added another buddy,
Bill. Three times a week, his wife stir-fries tofu with chard. “It’s
this gunk she calls superfood. I call it soylent green.”

He pauses a beat before adding, “I guess I’m grateful she gets me to eat
it.”

**Related: **[The Best Sources Of Protein For
Men](http://www.menshealth.com/weight-loss/worlds-best-protein-sources)

Long the foundation of a vegetarian diet, tofu provides protein with
little of the saturated fat and none of the moral indigestion that comes
with meat.

Moreover, in the past decade, research has emerged suggesting that
scarfing down soy may also play an active role in extending our lives.
In 1999, [soy
protein](article.do?site=MensHealth&channel=nutrition&category=diet.strategies&conitem=4e1a99edbbbd201099edbbbd2010cfe793cd____)
earned a highly coveted FDA-allowed health claim: Diets that include 25
grams—about a pound of tofu—a day may reduce the risk of heart disease.

**Related: **[30 Easy Ways to Save Your
Heart](http://www.menshealth.com/health/heart-saving-tips)

Add to this the number of studies showing that soy protein might also
help protect against prostate cancer, and suddenly the stuff starts
looking like powerful medicine for men.

Of course, most medicines have side effects.

And when you consume soy protein, you’re actually courting the Mr. Hyde
side of two natural drugs: genistein and daidzein. Both act so similarly
to estrogen that they’re known as phytoestrogens (plant-produced
estrogens).

Soybeans couldn’t care less about human sex characteristics—genistein
and daidzein may have evolved to act as chemical defenses against fungi
and grazing animals. (They aren't very effective deterrents, apparently,
since soy meal is widely used to feed livestock.)

But when humans consume these compounds in high enough quantities, they
may experience gender-bending nightmares like James Price’s.

**Related: **[How to Banish Your Man
Boobs](http://www.menshealth.com/fitness/banish-your-man-boobs-0)

What’s more, studies of these phytoestrogens in leading peer-reviewed
medical journals suggest that even lower doses—such as the amount in the
25-gram [soy
protein](article.do?site=MensHealth&channel=nutrition&category=diet.strategies&conitem=4e1a99edbbbd201099edbbbd2010cfe793cd____)
target cited by the FDA—have the potential to wreak hormonal havoc.

Here are a few of the recent findings across the life stages of men.

**Babies: Weaned On the Bean**

A whopping 35 percent of bottle-fed babies in the United States receive
at least some of their protein from soy.

The American Academy of Pediatrics (AAP) is taking steps to change this:
It recommends that all infants who cannot be breastfed be given
cow’s-milk formulas as the first preferred alternative. Healthy
full-term infants should be given soy formula only when medically
necessary, the AAP’s 2008 report states.

**Relate: **[5 Parenting Hacks You Won’t Find In Baby
Books](http://www.menshealth.com/guy-wisdom/easy-parenting-hacks)

Babies with an extreme form of lactose intolerance fall into this
category, but many others who suffer from colic and excessive crying are
switched to soy formula despite a lack of proven benefits.

Paul Cooke, Ph.D., a reproductive biologist at the University of
Illinois, has studied mice raised on enough genistein to make their
blood levels comparable to those of human infants fed soy formula.

Among other worrisome findings, he discovered significant shrinkage of
the thymus gland, a key part of the immune system. “The thymus,” says
Cooke, “is like a finishing school for white blood cells—it’s where they
go to mature.”

Whether the same effect occurs in human infants is difficult to say, but
a 2001 study in the Journal of the American Medical Association surveyed
over 800 adults, ages 20 to 34, who were fed either soy-based or
cow’s-milk formulas during their infancy.

One of the few differences to emerge was that the group raised on soy
formula regularly used more asthma and allergy medications in adulthood.
Was this just a quirk of the sampling—or could it represent a subtle
impairment of immune function?

“I don’t know the answer,” says Cooke. “But the point is I don’t think
anyone knows. There are 20 million people in the United States alone who
have consumed soy formula as infants. When people ask me about doing
experiments, I tell them we already are—with a large chunk of the
country’s population.”

For now, at least, the United States is gambling that widespread use of
soy formula won’t lead to long-term consequences.

In 2005, Israel’s health ministry recommended that soy products be
limited in young children and, if possible, avoided altogether in
infants. In issuing such a caution, Israel joined France, New Zealand,
and Australia in officially embracing a better-safe-than-sorry approach
for the next generation.

**Teens to 20s: Faux Muscle Fuel**

Most weightlifters, whether they’re dedicated competitors or occasional
gym rats, understand the importance of protein in muscle building and
repair. And research has shown that the timing of when you swallow that
protein is just as critical—a fact that’s created a market for
easy-to-consume protein supplements.

**Related: **[Workout Nutrition: What and When to Eat to Build
Muscle](http://www.menshealth.com/nutrition/workout-nutrition-for-muscle-building)

“It’s kind of hard to throw a steak down right before or after a
strength workout,” says William Kraemer, Ph.D., a professor of
kinesiology and a preeminent researcher of strength training and human
performance at the University of Connecticut.

Protein supplements allow an athlete to dump a scoop of powder in with
some juice and chug what he needs, when he needs it.

Giant canisters of the stuff line the shelves at GNC and similar
health-food stores nationwide, each brand touting its unique
muscle-building properties. The most common sources of protein used in
them are soy, whey, and casein.

But the latter two, which come from animal sources, are more expensive
to produce than soy. The question currently being debated by strength
trainers and researchers is this: Does soy’s relative affordability come
at a cost to muscle gains?

**Related: **[The Best Protein Powder For
Men](http://www.menshealth.com/nutrition/best-whey-powder)

In a 2005 study in the Journal of Nutrition, researchers comparing soy
to casein concluded that “the biological value of soy protein must be
considered inferior to that of casein protein in humans.”

Among other disadvantages, the researchers found, a significantly larger
portion of soy is degraded to the waste product urea. Moreover, it
contributes to less protein synthesis in the body.

"A protein like whey has much more robust biological effects than soy,”
acknowledges Kraemer.

In terms of strength gains, however, he says more research is needed
before he can provide definitive guidelines.

“But my personal opinion is that soy protein is cheaper and whey protein
is higher quality,” he says. “There are also concerns that soy might
decrease a man’s testosterone production and increase his estradiol
production, which we tend to associate with female hormone production.”

**Related: **[Is Testosterone Therapy
Safe?](http://www.menshealth.com/health/low-testosterone-treatment)

After retiring from military service, James Price and his wife, Donna,
moved to a small farm in Texas.

He had a commercial pilot’s license and split his time between flying
and working the land. His passion was raising and training quarter
horses that he broke himself. Price lived the kind of cowboy lifestyle
that few of his friends, even those decades younger, had the stamina to
sustain.

Donna cooked well-balanced meals, nothing fancy, just standard American
fare. It was a good life.

Then Donna developed glioblastoma multi-forme, a lethal type of brain
cancer. When she died, Price, then 55, was left to cope not only with
his grief but a radical change in his daily routine. Not surprisingly,
the diet of the new widower took a hit.

“All of a sudden,” he says, “I was living on not-so-healthy meals I’d
make for myself.”

**Related: **[5 Healthy Eating Hacks For Guys Who Hate to
Cook](http://www.menshealth.com/nutrition/easy-ways-eat-healthy)

He saw a product advertised on TV called Ensure; it was supposed to
provide adults all the vitamins and minerals and other vital nutrients
necessary for health. He also started drinking milk, a favorite from his
childhood that he figured would supply protein and other nutrients.

Unfortunately, Price soon discovered he was lactose intolerant.

“I switched to soy milk because it’s lactose-free,” he says, “and I had
heard that soy milk is supposed to be good for you.”

He tried it and liked it. Soon soy milk became a regular item on his
shopping list, something he bought on autopilot.

In the wake of Donna’s death, Price’s body as well as his emotions began
to change, often in ways that were hard to separate from normal grief.

Mood swings and a decrease in libido are not unusual companions to
bereavement. But Price had a nagging sense that something was off.

“I was becoming much more sentimental,” he recalls, describing his
emotions as almost feminine. “I’d break out and cry at a sad movie, that
kind of thing. It just wasn’t like me.”

When Price began dating again, it was as if the sexual aspect had
evaporated. “I enjoyed the company of women,” he says, “but it was just
like they were my friends. Even if I had wanted to do anything physical,
I couldn’t have.”

**Related: **[5 Easy Ways to Increase Your
Manpower](http://www.menshealth.com/health/5-easy-ways-increase-your-manpower)

The gynecomastia that eventually developed became deeply humiliating for
Price. He stopped wearing T-shirts even on the hottest days, fearing his
friends and neighbors might see the telltale bumps beneath the fabric.
His breasts by this point resembled the buds of a pubescent girl.

Never once in the subsequent yearlong ordeal of medical testing did it
cross his mind that soy milk might be the cause.

“I had no idea,” he says. “I never gave it a second thought.”

The day Dr. Lewi asked him to stop drinking the stuff, he immediately
complied. He also began checking the ingredient labels on all other
items he regularly consumed. If Dr. Lewi was right, going cold turkey on
soy just might begin to reverse the symptoms.

Over the next several months, blood tests revealed Price’s estrogen
levels were, indeed, dropping steadily back toward normal.

Even better, the extreme nipple tenderness began abating. Eventually,
his breasts stopped hurting completely and he gradually began feeling a
little more like his old self.

Dr. Lewi, who had searched the medical literature extensively when
trying to solve Price’s case, had come across no papers linking soy to
gynecomastia.

Realizing his obligation to warn other doctors about the possibility, he
told Price he wanted to follow him for several more months and
eventually write up his case for a medical journal.

Price readily agreed, grateful for the chance to spare others from his
ordeal.

**20s to 40s: Privates in Peril**

In a Harvard study published last year in the journal Human
Reproduction, Jorge E. Chavarro, M.D., Sc.D., and his colleagues found a
strong association between men’s consumption of soy foods and decreased
sperm counts.

**Related: **[4 Ways to Boost Your
Fertility](http://www.menshealth.com/sex-women/fertility-cheat-sheet)

Ninety-nine men reported their intake of 15 different soy-based foods,
then underwent semen analysis. Those in the highest category of daily
soy intake averaged 32 percent fewer sperm per milliliter of ejaculate
than those who went sans soy.

Dr. Chavarro cautions that this doesn’t prove cause and effect, and that
it’s too early to counsel men to avoid soy foods in the hope of boosting
fertility.

“But clearly, this story is just starting,” he says. “More studies need
to be conducted.”

If shooting blanks is worrisome, how about being unable to shoot at all?
Two other recently published papers reveal that at least one soy
component clearly impairs erectile function in animals—and may do so in
men as well.

The studies, published in the Journal of Andrology and Urology
respectively, looked at the effect of daidzein on the sexual function of
male rats.

Moderate doses of the phyto-estrogen administered either in youth or
adulthood significantly affected the quality of their erections. Among
other changes, the daidzein-exposed males produced less testosterone,
had softer erections, and experienced biochemical changes to their
penile tissues that left these tissues less elastic and less capable of
complete blood engorgement.

**Related: **[10 Myths About Erectile
Dysfunction](http://www.menshealth.com/health/erectile-dysfunction-myths)

While acknowledging that rat results do not always directly translate to
humans, the authors of the first study suggest that this time there’s
reason to believe they will.

They cite, among other things, a 10 percent higher incidence of erectile
dysfunction in Chinese men known to consume high amounts of soy compared
with Americans who avoid it.

The authors of the Urology study sound a similar warning. They argue
that it’s reasonable to believe that men who consume lots of daidzein
could experience tissue changes similar to those seen in another mammal.

Yufeng Huang, M.D., a coauthor on both papers, says that the “moderate”
dose used in the animal studies leads to approximately the same blood
level of daidzein in men who eat soy every day, a common practice in
Asia. He believes soy represents a novel and previously overlooked risk
factor for ED.

“We are now recommending that soy be avoided by patients with erectile
dysfunction,” Dr. Huang says. And because erectile dysfunction increases
with age, he also suggests that men ages 40 and above limit their soy
intake.

**Related: **[Do You Need Erectile Dysfunction
Drugs?](http://www.menshealth.com/health/erectile-dysfunction-drugs)

**50s and Beyond: Brain Drain**

Last summer, Eef Hogervorst, Ph.D., of England’s Loughborough
University, and other researchers published a study on soy products and
dementia risk.

The researchers focused their attention on older Indonesians, members of
a culture in which tofu has long been a dietary staple. Hogervorst says
her team began the study confident of finding a benefit from tofu’s
phytoestrogens.

“Almost everything we’d learned from animal and cell-culture work
indicated that estrogenlike compounds protect the brain,” she says.

In older men and older women alike, however, they found exactly the
opposite indication: Participants over age 68 who were regularly eating
the most tofu had double the risk of dementia and memory impairment as
those consuming a more moderate amount.

“We were very surprised by this at the time,” says Hogervorst, “but a
new consensus is starting to form now. Hormones and hormonelike products
are not very good for people over 65.”

**Related: **[8 Daily Habits That Will Keep Your Brain Young and
Sharp](http://www.menshealth.com/health/keep-your-brain-sharp)

In terms of soy itself, Hogervorst suspects its reputation is changing.

“For a long time now,” she says, “people have been finding only good
things about phytoestrogens. Gradually, as some contrasting information
accumulates, the paradigm changes 180 degrees and you see people arguing
that phytoestrogens are all bad. The truth probably lies somewhere in
the middle.”

Dr. Lewi's case report on James Price's condition was published in the
May/June 2008 edition of Endocrine Practice, a journal read by many of
the nation’s in-the-trenches endocrinologists. Thanks to this, doctors
now have a newly documented agent to consider when evaluating
gynecomastia.

For his part, Dr. Lewi believes that soy products in moderation can
still be a healthy part of a man’s diet.

“The problem,” he says, “is when a thing like soy is touted as this
wonderful panacea for health, and people end up going overboard on it.”

A final twist in the Price case, however, shows how difficult it can be
to avoid soy. During the follow-up blood testing Price agreed to
undergo, his estrogen levels continued to drop, in a virtually linear
fashion, back toward normal.

Then, several months later, and seemingly for no reason, the positive
trend reversed. As soon as he saw that Price’s estrogen was once again
climbing, Dr. Lewi called his patient.

Before Dr. Lewi could even announce the results, Price said, “I already
know what you’re going to tell me, Dr. Lewi. You’re going to say my
estrogen level is coming up."

Dumbfounded, Dr. Lewi asked Price how he knew that without seeing the
test results.

Price explained that after switching from soy milk to lactose-free milk,
he was in the grocery store one day and bought some more Ensure. Though
he’d followed Dr. Lewi’s advice and checked the labels on virtually
every product he purchased, he’d neglected to check Ensure.

“It’s advertised as having vitamins and minerals and all the stuff you
need to stay healthy,” he says.

**Related: **[The Best Multivitamins For
Men](http://www.menshealth.com/health/best-multivitamins-men)

Only after his breasts started hurting and growing again did it occur to
Price that Ensure might also contain the last thing his body needed. He
checked the label: Ensure contained soy protein. He told Dr. Lewi that
he threw out the rest and was no longer drinking it.

Subsequent blood tests showed that this was enough to send Price’s
estrogen back in the healthy direction.

Several months later, his estrogen levels—once higher than those of most
women—were in the low-to-normal range for healthy men. They’ve remained
in that range ever since, but the physical changes to his penis, his
loss of sexual desire, and his heightened emotions have persisted.

**Related: **[The Male Libido
Crisis](http://www.menshealth.com/sex-women/male-libido-crisis)

And while all pain associated with his breasts has disappeared, the
tissue unfortunately remains swollen, a consequence of fibrotic tissue
changes that take place with long-term gynecomastia.

Although Price remains self-conscious about it, he’s reluctant to try
the only cure—cosmetic surgical reduction. There are too many risks, he
says—bleeding, infection, problems with anesthesia—to justify going
under the knife at this point in his life.

As for other men who might one day develop a similar problem, Price’s
advice is unequivocal: Go to your doctor at the first sign of pain or
swelling. Symptoms caught and treated early are often reversible.

Price also acknowledges that his body may have an above-average
sensitivity to soy’s phytoestrogens.

Still, his experiences have taught him that the foods we eat are not
always what we think they are. Soy protein today is an ubiquitous,
profitable, and often buried ingredient in a bewildering number of
packaged foods. More than most people, Price was doing his best to avoid
it. But he was still tripped up.

“In today’s supermarkets,” he says, his voice weary, “you can’t hardly
get anything without at least some soy in it.”
