Soy Milk Benefits For Women

Common word of mouth and some studies have it that soy-based foods contain estrogenic properties that will halt anabolic and growth processes in bodybuilders. Unfortunately, the problem with information is that there are two kinds: information and misinformation.

In this article, I will assess the pro's and con's of soy-based foods and disseminate research studies and expert opinions to arrive to a strong and formidable conclusion about soy being a bodybuilder's friend or foe. Often times in the fitness industry, hot new trends get a spin.

For instance, one can find any one positive factor and put a spin on it to make it seem like a good thing. Obesity for example, we know it is detrimental to overall well-being, however, one could argue it is an effective means for preventing osteoporosis.

This same kind of spin has occurred with regards to soy. However, I am going to start this in-depth analysis as Bill O'Reilly starts his show The Factor with,

Adversaries propose the notion that plant estrogens called phytoestrogens (the chemical name is isoflavones) reduce testosterone levels and they also make the association that soy brings about feminine characteristics with excess estrogen levels.

It is highly probable that these same cynics are not natural bodybuilders, which is a conundrum in itself considering excess testosterone (anabolic steroids) actually induces real life feminine characteristics in men (Birkeland et al. 1994).

Furthermore, this is just folklore at best that soy-based foods or any foods that have estrogenic properties are associated with feminine characteristic or hormonal outcomes. Bottomline: It is all hogwash.

Now, the support for this magical food source that I am about to provide will be scientifically, logically and rationally-based and it will literally shock you as to how good soy foods really are.

What follows is an unbiased view from both sides on the issue. This is uncommon on most internet articles or even paper-copy articles of which most writers will only cite references to support their claim. However, in order to be fair in the critique and to avoid implications of bias, I will provide arguments from both sides.

Ultimately, a verdict will be reached regarding each claim based on the reliability, credibility, and logical inference and deduction from the supporting evidence.

Claim One

Claim: Soy Suppresses Testosterone

Supporting Evidence:

Some studies have shown that soy consumption is associated or inversely related to suppression of testosterone levels (Dillingham et al., 2005; Gardner-Thorpe et al., 2003; Habito et al., 2000; Nagata et al., 2000, Ziesel et al's study [as cited in Squires]).

Rebuttal: Soy Does Not Significantly Suppress Testosterone

Supporting Evidence:

Some studies have also shown that soy consumption is not associated or inversely related to suppression of testosterone levels (Kurzer, 2002; Maskarinec et al., 2006; Mitchell et al., 2001; Nagata et al., 2001).

The Dillingham et al. (2005) study was meant to investigate soy protein's strong association with reducing prostate cancer risk by modulation of serum hormones. They made no such implication of the modest testosterone reductions being associated with feminine traits or negative health consequences. However, they did argue for soy having favorable effects on prostate health in men.

The Gardner-Thorpe et al. (2003) study also found soy to have advantageous effects against prostatic disease and heart disease. The idea of these testosterone reductions making these men less manly or smaller was not indicated.

Interestingly, in the Nagata et al. (2000) study, they may have concluded the inverse relationship of soy intake and testosterone levels, but they also stated that these correlations were of borderline significance.

In fact, in a study published 1-year later, Nagata et al. (2001) found no change in testosterone with soy consumption. In the Maskarinec et al. (2006) study, it was suggested that the reduction in prostate cancer risk could be regulated by a non-hormonal mechanism.

Thus, soy does not reduce testosterone concentrations, but actually lowers a man's risk of prostate cancer.

Furthermore, the studies that found testosterone levels to slightly decrease classified the relationship as correlation or association. This does not mean that the outcome was based on cause. In correlation, it is not a cause-effect outcome, rather, it is just a relationship, but the logic to that relationship is not fully understood.

In other words, who is to say that these lower testosterone levels in these subjects was not a result of eating a diet lower in saturated fat and higher in dietary fiber? It is commonly known that low-fat and/or high-fiber diets are correlated with lower testosterone levels (Berrino et al., 2001; Dorgan et al., 1996; Hamalainen et al., 1983; Hamalainen et al., 1984).

However, with a bodybuilder who includes variety in the diet such as eating lean red meat, dairy products and poultry in moderation in conjunction to proper intense training, soy's modest testosterone reducing effects would be counterbalanced, but the prostate and other health benefits would be reaped.

Another factor to investigate in the testosterone suppression claims is the methodology of their supporting studies. Some of these studies had their participants either exclusively consume soy (Habito et al., 2000; Zeisel et al's study [as cited in Squires]) OR they mega dosed on soy to isolate the effects of soy (Habito et al., 2000; Ziesel et al's study [as cited in Squires]).

In Habito et al's (2000) study, the only difference was that in one group subjects had 150 grams of lean meat protein, in the other group; they had 290 grams of tofu. Nearly double the amount of soy protein in comparison to the lean meat protein.

Again, in the real world, most people would not just eat soy-based foods in exclusion of others, nor would they mega dose. Hence, these findings have limited ecological validity (real-world application).

Squires (2004) reported the following:

Most concerns about soy have centered on the fact that it is a rich source of isoflavones, substances that mimic the effects of the female hormone estrogen.

To determine what these plant-based chemicals might do, Steven Zeisel and his colleagues at the University of North Carolina at Chapel Hill fed mega doses of soy to men as part of a recent National Cancer Institute study.

Nipple discharge, breast enlargement and slight decreases in testosterone occurred with the mega doses. But, 'We still couldn't find anything that was serious, and we went up to doses that are probably 30 times what you could get from normal foods,' Zeisel said. 'I don't think that there are a lot of estrogenic worries. Your testicles will not shrink and you won't have massive breast enlargement' from eating soy.(p. HE01).

Conversely, ones testicles would shrink from long-term use of anabolic steroids.

Verdict Of The Claim: Guilty On All Counts

1. Distortion and bias of research findings to sell or promote meat and dairy proteins as the be all.
2. Not viewing both sides of the issue, but instead only citing studies that support the claim.
3. Extrapolating insignificant findings to support an irrelevant claim.
4. Putting a spin on the findings by making an extrapolation or blind inference into hormonal alterations of which were actually found to promote better health.

Claim Two

Claim: Soy Protein Does Not Aid In Muscle Growth

Supporting Evidence:

One study using pigs as subjects, suggested that soy protein intake induced protein degradation (Lohrke et al., 2001).

Rebuttal: Soy Protein Aids In Muscle Growth

Supporting Evidence:

One study using rats as subjects, suggested that soy protein prevented protein degradation (Nikawa et al., 2002). Three studies actually looked at the effects of supplementing with animal protein vs. soy protein during a resistance training program in humans (Brown et al., 2004; Candow et al., 2006; Haub et al., 2002).

In Haub et al's (2002) study, it was shown that there were no significant differences in strength, hypertrophy, muscle cross-sectional area, or muscle creatine levels when comparing meat protein vs. soy protein consumption during resistance training (Haub et al., 2002).

Unbelievably, I came across an anti-soy article online that distorted the findings indicating that there was a 30% increase in muscle cross sectional area compared to soy!

Personally, I do not know where this interpretation came from because I actually looked at the full-text article and the authors made it statistically and graphically clear that there were no significant differences in muscle cross-sectional area and concluded that the key factor in regulating muscle strength and hypertrophy was adequate protein intake, independent of the protein source (Haub et al., 2002).

In Candow et al's (2006) study, it was concluded that protein supplementation increase muscle strength and size, independent of the protein source.

In another study looking at the effects of a whey and soy supplemented diet in mice found that both protein sources had positive effects on antioxidant status and resulted in enhanced body composition (Elia et al., 2006).

Another study showed that skim milk led to greater muscle growth compared to soy protein (Wilkinson et al., 2007). However, it was found that milk and soy each led to a positive net protein balance (Wilkinson et al., 2007).

Therefore, as I said earlier, skim milk certainly is a great source of protein and it has its place in my diet, but, so does soy. In the Brown et al (2004) study, a comparison was made between whey and soy protein bars and their influence on lean body mass in college males in a weight training class.

It was found that both protein sources led to greater gains in lean body mass, however, only the soy protein preserved two aspects of antioxidant function, whereas the whey protein did not counteract the oxidative stress of exercise as effectively (Brown et al., 2004).

Remember that when it comes to making gains in the gym, it is not necessarily the workouts that promote growth; workouts stimulate growth, while nutrition determines how effective the response is to the stimulus. Thus, with the inclusion of soy, one may see greater and better recovery time, which would mean one could see better gains in the gym.

Squires (2004) reported the following:

As a protein source, soy ranks at the top of the list. But no need to take massive doses of soy protein supplements or powder to build more muscle. Eating a soy burger, a handful of soy nuts or a soy smoothie after a weight training session is plenty to help repair muscle, according to Jeff Potteiger, an exercise physiologist at Miami University in Ohio (p. HE01).

Now, I know many may disagree with this report above with soy being at the top of the list, I do as well. I personally believe whey, casein, and branched chain amino-acids (leucine in particular) to be at the top of the list.

In fact, it is well-known that whey and casein protein proteins are the best absorbed and provide the best results (Hansen, 2005). Furthermore, Hansen (2005) had no negative things to say about soy protein. He just mentioned that fact that since soy is derived from plant sources, it is an incomplete protein and may not be digested or absorbed as well as milk proteins (Hansen, 2005).

However, if soy protein is taken in combination with whey and/or casein, the protein quality or lack of essential amino acids are no longer issues (Hansen, 2005; Margen et al., 1991). Thus, the point being made here is that including soy as a protein source can add variety to one's diet and protein-source arsenal.

Verdict Of The Claim

This 30% difference claimed by this anti-soy writer is similar to saying 3/10 people saw better gains with the meat protein, which is not even significant looking at from a common-sense point of view. However, as a well-informed and critical reader of information, one should certainly respect the statistical level of significance of 0.05 when interpreting findings.

So, in this study (Haub et al., 2002), there were no significant differences, thus one can slice the results any which way, but at the end of the day, no significant differences. Therefore, one needs to question the motives (i.e. personal bias, selling something, protection of product sales) for certain individuals taking results from research studies out of context.

Paul and Elder (2001) suggested the following excerpt for identifying questionable professional thinking:

This professional seems to be viewing the situation in a questionable manner because... (here you are trying to determine whether the professional seems to have been influenced by some vested interest to exclude relevant information or whether the professional was simply engaging in poor-quality thinking because of naiveté or similar reason (pg. 303).

Claim Three

Claim: Soy Protein Is Associated With Testicular Cell Death And Infertility

Supporting Evidence:

Some studies have suggested that one of the compounds in soy (genistein) induces testicular death and infertility in laboratory animals and human cells in test tubes (Anderson et al. 1997; Casanova et al., 1999; Hopert et al., 1998; Kuma-Diaka et al., 1999; Setchell et al., 1987; Strauss et al., 1998).

Rebuttal: Soy Protein Suppresses Cancer Growth

Supporting Evidence:

Many studies have shown that soy consumption actually deters proliferation of cancer cells (Geller et al., 1998; Hillman et al., 2001; Santibanez et al., 1997; Squadrito et al., 2003).

A preponderance of studies have also shown soy to be beneficial in prevention of heart disease, prostate cancer, diabetes, and osteoporosis (Colacurci et al., 2005; Jacobsen et al., 1998; Omoni & Aluko, 2005; Taku et al., 2007; Tikkanen et al., 1998; Vitolins et al., 2001; Wiseman et al. 2000; Zhan & Ho, 2005).

Verdict Of The Claim: Guilty As Charged

Sometimes in research, findings have statistical significance, but this does not mean they have practical significance.

Gay & Airasian (2003) stated the following:

The fact that results are statistically significant does not automatically mean that they are of any educational value, that is, that they have practical significance...

Statistical significance only means that your results would likely occur by chance a certain percentage of the time, say 5%. This only means that the observed statistical relationship or difference is probably a real one, but not necessarily an important one (pg. 495).

Interpreting findings from animal studies is in of itself an irrelevant inference.

Brody (1998) reported the following:

Though nearly all that is known about the cancer risk of chemicals in foods comes from studies of laboratory animals exposed to very high doses of each suspect chemical, the committee urged caution in drawing conclusions from animal studies about cancer risks in humans.

Animal studies have limitations, the report pointed out, because the bodies of animals and people might handle a chemical differently, and the effects of ingesting a single substance in isolation may differ from the effects of consuming it as part of a varied diet. Also, an animal study uses very large doses of a chemical that people are exposed to in only minute amounts (pg. 184).

The committee referred to in the above excerpt was the Research Council Committee, and the report was 'Carcinogens and Anticarinogens in the Human Diet,' which was based on an exhaustive review of scientific reports and other relevant information (Brody, 1998).

The Benefits Of Soy

For the intensive purposes of this discussion, I will use soy milk as the common example reference food. Furthermore, I will use milk as the opposing example reference food. This is an important comparison as it is relevant to the concept of this article.

In past years, milk has always been referred as a man's kind of food source with the media mentioning that milk does a body good, milk is good for bones, and that milk will make one grow big and strong. However, I am in no way making the claim that whey and casein are not good protein sources, nor that milk in moderation is not good. I am simply using both food sources as an analogy to symbolize soy as those supporting soy and milk for those against soy

First of all, it was Arnold Schwarzenegger himself who became a believer that a vegetarian could build big muscle and become a champion bodybuilder (Schwarzenegger, 1998). This vegetarian goes by the name of Bill Pearl. Accordingly, Soy milk has several benefits worth investigating.

A Good Protein Source For Bodybuilders

Soy milk has a good amount of protein per serving (~7 grams per cup). When one thinks of soy-based foods, do me this favor. Check the protein content in the ingredients please. In most cases, you will find a wonderful macronutrient profile which is mostly protein, complex carbs, and healthy fat with fiber to boot!

Additionally, there are different brands of soy milk that contain different concentrations of carbohydrates, fat, total calories, and fiber. Research has shown that the lower carbohydrate and higher fiber brands have lower glycemic and insulinemic indices (Torres et al., 2006).

Low Glycemic Index and Insulinemic Index and Soy's Fat-Burning Effects

A lot of people know skim milk has a low glycemic index, but many do not know that skim milk has a high insulinemic index (Ostman et al., 2001).

In other words, although blood glucose levels stay normal, milk spikes insulin. And if we recall, insulin is a potent inhibitor of fat oxidation (Manore & Thompson, 2000; McArdle et al., 2001). However, soy milk has been shown to have both a low glycemic and insulinemic index (Blair et al., 2006; Torres et al., 2006). Thus, soy milk allows one to stay in fat-burning mode longer.

In addition, there have been studies that have actually found soy protein intake to be associated with improved fat oxidation markers (Morifuji et al., 2006). In fact, it has been found that soy protein leads to greater reductions in body fat content and blood glucose levels compared to casein (Nagasawa et al., 2002) or whey protein (Aoyama et al., 2000).

Environmental Enhancement

As if the aforementioned reasons are not good enough, soy milk is even involved in saving our planet! Some products are proud to claim their products to be made by 100% wind energy (Helping the Environment, 2007). Thus, soy indirectly helps in preserving the atmosphere and preventing further global warming.

Antioxidant Capacity And Healthy Fats

For this one, I'd like to borrow a line from Ocean's Eleven. Remember when Brad Pitt was calmly and confidently making demands to the Casino owner on his cell phone in the casino? The line that comes to mind is, 'I got two words for you, mini-bar.' Well, I got two words for you, 'Iso-flavones.'

Isoflavones have favorable effects on reducing prostate cancer, heart disease, and cholesterol (Taku et al., 2007; Vitolins et al., 2001; Zhan & Ho, 2005). Incredibly, soy milk also has alpha-lipoic acid (ALA).

Some soy milk products contain upwards of 300mg of ALA omega-3's; a serving of 2% milk contains only 20mg of ALA omega-3's. Research has shown ALA to aid in the fight against free radicals and oxidative stress (Packer et al., 1995; Packer et al., 1997).

Tastes Great

Sorry, but this is true. Personally for me anyway, I find soy milk to taste so much better than milk. However, to provide better proof than personal opinion, soy was the proud recipient of the 2007 American Culinary Chefs Best Award for Best Taste.

Forum Threads:

• Soy Milk or Skim Milk?- Started By DCpapi07
  'Which is better for mucle growth?'
• To all Soy-haters: let's have a look at milk.- Started By Dr.P
  'The interesting thing is that cow milk may very well have some estrogenic impact as it apparently contains real estrogens: estrone and estradiol. the total amounts are not very high and apparently they are closely related to the fat fraction of the milk.'
• How's soy milk compare to regular milk?- Started By Someguy150
  'I've been using Silk Enhanced (more vitamins) soy milk for weeks instead of regular milk now. It tastes similar or better to me, and the nutritional value (to skim milk) is also very similar.'

Arnold's Exact Words On Milk

In the movie pumping iron, Arnold replied to a spectator about milk. The spectator asked, 'Do you drink milk?' Arnold replied, 'No I drink no milk.' 'Milk is for babies, when you grow up you have to drink beer.' So, as Arnold said, Milk is for babies.

Summary

Honestly, Soy sounds like a bodybuilder's best friend to me, based on all these nutrient values and benefits.

• Low sodium AND high potassium which equates to a good pre-contest food. Interestingly, soy milk has just about the perfect balance/ratio of these two electrolytes.
• Low caloric value. A cup of light plain soy milk has 70 calories per cup.
• Low glycemic AND insulinemic index means one will stay in a fat-burning state with lower insulin levels and higher glucagon levels.
• High protein source, dare I say more about this being important to bodybuilders?
• Heart health. Often, bodybuilding is associated with bad health and for good reason. With the unfortunate widespread use of anabolic steroids, diuretics, and testosterone prohormones, it is no surprise that bodybuilding has sort of gone back into the closet.

In fact, one recent study (Brown et al., 2006) found prohormones do not even produce any ergogenic or anabolic effects in men, but it found that the use of these supplements can actually raise the risk for certain negative health risks. However, with the advent of natural bodybuilding, bodybuilding can be one of the healthiest endeavors one can partake.

If done the right way, one can eat healthy with variety, balance, and training that includes ever-important cardio. The logic to natural bodybuilding is: You are what you eat AND you are what you do. It is not, you are what you take.

The answer to this debate is quite simple; Everything in moderation. In my personal opinion, when we receive exogenous testosterone (anabolic steroids), this sends the signal to the body that there is an abundant supply of testosterone coming from the outside, so the body shuts off endogenous testosterone production.

This is why many former anabolic steroid users shrink in body size so substantially, that you can't even recognize them later in life. Their bodies stop producing testosterone naturally, which by the way confirms the common side effect of shrinkage of the testes.

On the other hand, when there are low levels of testosterone in the body, this sends the signal for the body to actually increase testosterone production. Thus, one may deduct that if soy products actually incur minor reductions in testosterone, this may actually lead to an increase in endogenous production of testosterone! Who would have thought, huh!?

The key to this entire riddle is everything in moderation, which leads to balance (homeostasis). Personally, whey and casein are the top protein sources one can consume, lean red meat and dairy products have many benefits and I personally consume these food sources on a regular basis.

However, the point of this article was to understand that soy protein has several benefits and can be included as part of a regular diet. So the next time you read or hear of someone saying soy halts gains in the gym, just smile to yourself and continue walking with that impeccable truth of knowing you are creating variety in your diet (via not blogging about how it sucked to eat tuna every other meal) and you are doing your body and health good while still winning bodybuilding shows.

And finally, I'd like to revise Arnold's notion and finish with, 'Milk is for babies, when you grow up you have to drink soy milk.'

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The information provided in this article is for educational and informational purposes only and does not serve as a replacement to care provided by your own personal health care team or physician. The author does not render or provide medical advice, and no individual should make any medical decisions or change their health behavior based on information provided here. Reliance on any information provided by the author is solely at your own risk. The author accepts no responsibility for materials contained in the article and will not be liable for any direct, indirect, consequential, special, exemplary, or other damages arising from the use of information contained in this or other publications.

Copyright © Ivan Blazquez, 2007. No part of this publication may be reproduced or transmitted in any form without the prior written permission of the copyright holder and author of this publication.

James Price’s breasts had been painful and swollen. It looked as if gum balls were implanted underneath each nipple. The slightest touch triggered throbs.

For Price, a retired U.S. Army intelligence officer who once flew attack helicopters in Vietnam, these changes were more than just physically uncomfortable.

“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

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.

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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 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.

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“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.’”

Price explained that he’d developed lactose intolerance in recent years and had switched to soy milk 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 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.”

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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 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

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

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 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.

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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

“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

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.”

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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

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.”

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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

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.

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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?

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

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

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

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.”