Wartman describes the Cornucopia Institute’s recent report in which they describe finding residues of hexane in some soy food ingredients. The Cornucopia Institute gave few details about how much hexane they actually found and there is no evidence that the amounts typically found in soy foods are harmful to consumers. However, in the interest of worker and environmental safety, as well as trying to limit any potential harm from hexane residues, I cannot fault anyone for avoiding soy products produced with hexane. As Wartman points out, there are companies that make soy meats without using hexane, such as Tofurky and Field Roast.

But this is where Wartman and I part ways. While there are legitimate concerns regarding soy, Wartman cherry-picked the studies and ignored the vast majority of research. For the topics in this article, I will cover the full range of research findings, both pro and con.

A little background: Soy contains isoflavones which have the ability to bind to estrogen receptors and can affect thyroid hormone (especially if someone has iodine deficiency). There are about 25 mg of isoflavones in one serving of soy.

Breast Cancer

Wartman implicates soy as a cause for breast cancer, mentioning only one study. Unfortunately, she didn’t cite the study correctly, so it is not clear to which she was actually referring. In any case, here is a run down of the research.

Case-control studies on soy and breast cancer have been generally encouraging to those with soy in their diets, with about half associating soy with a lower risk for breast cancer and the other half showing no effects.

Prospective studies, which are generally a higher level of evidence than case-control, have also been very positive. Of the six studies done on populations with higher soy intakes (about one to two servings per day is the typical upper intake amount), the Singapore Chinese Health Study (21), the Shanghai Women’s Study (22, 23), and the Japan Public Health Center study (26) all found that higher intakes of soy were associated with a reduced risk. The Japan Collaborative Cohort Study (17) and the Japan Life Span Study (30) found no association. The European Prospective Investigation into Cancer-Oxford (24), which contained a large number of vegetarians, also found no association. Regarding the lack of association in the European study, some have speculated that in order to receive benefits from soy, exposure must occur during adolescence when breasts are developing, while Western vegetarians often adopt the diet as adults.

As for women with breast cancer, including those with tumors that grow in response to contact with estrogen (known as estrogen receptor positive), the authors of the recently published Women’s Healthy Eating and Living Study write:

Our study is the third epidemiological study to report no adverse effects of soy foods on breast cancer prognosis. These studies, taken together, which vary in ethnic composition (two from the US and one from China) and by level and type of soy consumption, provide the necessary epidemiological evidence that clinicians no longer need to advise against soy consumption for women diagnosed with breast cancer.

Dementia

Wartman cites the 2000 Honolulu-Asia Aging Study, saying that it linked soy with an increased risk of Alzheimer’s disease and brain shrinkage. Actually, this study does not mention Alzheimer’s Disease, although it did measure cognitive function. Let me sum up the evidence on soy and mental cognition.

There have been twelve short-term (lasting one week to a year) clinical trials looking at the impact of soy on cognition, and all have shown soy to be helpful (44, 45, 48, 49, 47 50, 54, 55, 56) or neutral (51, 52, 57).

Epidemiological studies (unlike clinical trials), examine patterns of soy consumption and cognition in specific populations. One such study found tempeh (a fermented soy food) to be associated with improved cognition (9). Three reports from epidemiological studies have associated tofu with reduced cognition in some groups (2, 9, 53), but increased cognition in another group (42), and neutral in others (42, 53). The harmful findings for tofu in the epidemiological studies are likely due to confounding caused by the fact that people of lower economic status have traditionally eaten more tofu in Asian cultures as well as the fact that some tofu has been prepared using formaldehyde (at least in Indonesia from where some of these reports have come). The research as a whole provides little cause for concern.

Infant Formulas

Wartman suggests that soy-based infant formulas are “Perhaps the most alarming…” While I can understand the concern given that some infants are eating nothing but soy, the most important study to date, tracking adults who were fed soy formula as infants, provides assurance that there is no reason to be concerned about thyroid or reproductive function (95). Furthermore, the American Academy of Pediatrics and the National Toxicology Program considers soy formula safe.

The Beginnings Study is an ongoing study examining the effects of formula on child development (86). It is in its early stages with findings from children only a year old, but to date no negative effects of soy have been found on growth, sex organs, or neurological development compared to children on cow’s milk formula.

Some research shows that is best to choose a soy formula with DHA, and it is important to note that soy-formula is not intended for pre-term infants.

Feminizing Characteristics

Regarding the concern that soy could cause feminizing characteristics in men, there have been two case studies. In one, a man eating twelve servings per day of soymilk developed enlarged, sensitive breast tissue (123). In another, a man with type 1 diabetes was eating 14 servings per day of mostly processed soy foods for one year and developed erectile dysfunction (10), which normalized after ceasing the soy. While I would not recommend eating this much soy, one study used even much higher amounts of isoflavones and found no problems for most men (124).

As for sperm quantity and quality, while one epidemiological study raised concerns, albeit minor, about soy and sperm quantity (14), two clinical studies have shown no effects of soy (15, 126).

Thyroid

I do want to address one more issue that has recently arisen with the publishing of a clinical trial this year in which 16 mg/day of isoflavones in people with mild hypothyroidism appeared to cause an increased rate of advancing to overt hypothyroidism (78). Nine other clinical trials showed no effect of soy on the thyroid compared to placebo in people with presumably healthy thyroids (13, 60, 63, 64, 66, 68, 69, 71, 75) while the remaining five studies found small changes, all without physiological significance (61, 65, 70, 73, 74). People without hypothyroidism should have no problems with soy as long as they get enough iodine, but until we know more, people with mild hypothyroidism might want to avoid soy just to be safe.

Miscellaneous

In Soy: What’s the Harm?, I address other issues Wartman raised, such as mineral absorption (a non-issue) and traditional Asian intakes.

Conclusion

In addition to reducing the risk for breast cancer as mentioned above, soy also provides benefits for preventing prostate cancer, lowering LDL cholesterol, and improving menopausal symptoms. When you add up all the research on soy, there is no reason to think that two servings per day are harmful to most people, and good reason to think soy will provide some health benefits.

Originally published on JackNorrisRD.com

Thanks to Michael Pollan, many Americans are now aware that when a food boasts a health claim it usually means it’s actually not that healthy after all. But there’s one food that consistently flies below the radar despite its numerous health claims when found in processed and packaged foods: Soy. A long-time staple in the American health food repertoire, it is a prominent example of Pollan’s observation. And the research is mounting that soy foods are not only questionable in terms of their benefits, but in fact, may be hazardous to your health.

Most recently, the Cornucopia Institute conducted research on the processing of soy foods and found that the industry commonly uses hexane—a petroleum-based solvent and known neurotoxin—to process soy ingredients found in many “natural” food products.

Thanks to their research and consumer concern, the Cornucopia Institute announced last week that some companies have voluntarily changed their processing practices and eliminated hexane from their products. Unfortunately, there are still well over two dozen “all-natural” nutrition bars and veggie burgers that still use hexane to process soy.

But hexane processing is really just the tip of the iceberg when it comes to problems associated with eating soy—and many of the health problems are unknown to the general public.

In 1999, the FDA approved the health claim that soy is “heart healthy” and reduces the risk of cardiovascular disease. But this wasn’t without controversy. Two researchers for the FDA, Daniel Doerge and Daniel Sheehan stated that they were opposed to the labeling of foods containing soy as heart healthy since there was “abundant evidence that some of the isoflavones found in soy…demonstrate toxicity in estrogen sensitive tissues and in the thyroid.”

The two researchers refer to numerous studies that show the estrogenic quality of soy isoflavones have harmful effects on many in the population. Isoflavones are a type of phytoestrogen, or plant-based estrogen that mimics human estrogen. It functions similarly to other endocrine disruptors (which I wrote about here on Civil Eats) and binds to our estrogen receptors. Consuming soy elevates estrogen levels, which is correlated with increased risk for breast cancer (and other estrogen-sensitive cancers as well), as 80 percent of U.S. breast cancers are associated with estrogen supplementation. In one study reported in the American Journal of Clinical Nutrition, women who already had breast tumors were given a soy drink for 14 days and their breast tumor growth increased significantly.

In another study the researchers for the FDA refer to, consumption of soy is linked to brain aging, shrinking, and the development of Alzheimer’s disease. In this 35-year Hawaiian study of 8,900 Japanese men and 500 of their wives, tofu intake was the only factor that correlated with an increased occurrence of Alzheimer’s disease. The researchers wrote, “This finding is consistent with the environmental causation suggested from the earlier analysis, and provides evidence that soy (tofu) phytoestrogens causes vascular dementia.”

Perhaps most alarming is the use of soy-based infant formulas. They pose such a risk that the health ministers of the United Kingdom and New Zealand have advised parents not to use soy formula. Studies have found that soy-fed infants have estrogen levels an average of seventeen thousand times higher than infants fed human or cow’s milk.

For men, estrogen-rich soy is also problematic. The Israeli Health Ministry warns men to exercise caution in regards to soy consumption as it has been shown to lower virility—since eating soy reduces testosterone and increases estrogen. In one study presented at the 2007 conference of the American Society of Reproductive Medicine, researchers found that in subfertile men, those eating the most soy had forty-one million fewer sperm per milliliter than those who consumed none. The average amount consumed was equivalent to half a tofu patty. In the womb, excess estrogen causes abnormal sexual development and low sperm counts in boys and men.

As is clear from these studies, the phytoestrogens in soy are quite powerful. While other foods (flaxseed, garbanzo beans, and oats, for example) also contain some amount of phytoestrogens, soy contains the highest amount—and since it is often used in such large quantities as a replacement for meat or dairy, it’s more problematic than other foods. Proponents of soy often refer to the long history of its use in Asian cultures but they fail to mention just how much is typically eaten. In Japan the average amount of soy consumed on a daily basis is two tablespoons, in China it’s two teaspoons where it’s eaten as a condiment rather than a replacement for animal products.

In America however, since soy is in thousands of processed foods (usually in the form of soy protein isolate, soy isoflavones, textured vegetable protein, and soy oils) it accounts for a fifth of the calories in the American diet—not to mention the actual soy foods and drinks that some use as a replacement for meat or dairy. Soy isoflavones were actually denied status as “generally regarded as safe,” or GRAS, as a food additive by the FDA due to the many uncertainties surrounding them. A senior scientist for the FDA wrote, “Confidence that soy products are safe is clearly based more on belief than hard data.”

What’s more, unfermented soy (tofu, soymilk, soy cheese, ice cream, yogurt, soy protein shakes, soy protein isolate) contains high amounts of phytic acid which blocks mineral absorption—particularly calcium, magnesium, iron, and zinc; and soy is an unusual protein that is difficult to digest. Soy is also a goitrogen, meaning it depresses thyroid function and interferes with the absorption of thyroid hormones as well as the crucial mineral iodine.

Fermented soy (miso, natto, tempeh, and soy sauce), most commonly eaten in Asian cultures, is easier to digest and contains far less phytic acid. In addition to choosing fermented soy products over others, choosing organic soy products means avoiding the 91 percent of soybeans produced in this country that are genetically modified and highly contaminated with pesticides.

Why haven’t you heard many of these facts and figures when it comes to “heart healthy” soy? Soy production is a major player in the industrial food system. According to the USDA, in 2009 the total acreage of soybeans planted in the U.S. was 77.5 million acres, accounting for the largest source of protein feed and the second largest source of vegetable oil in the world. In 2008-09, the farm value of soybean production was $29.6 billion, the second highest among U.S. produced crops.

So let’s remember Pollan’s decree: “a health claim on a food product is a good indication that it’s not really food, and food is what you want to eat.” And in fact, this applies to nearly every health claim, even the ones that you might not suspect. It’s good to note, too, that when the food in question is one of the largest players in the industrial food system, you can bet we’re not getting the whole story.

Photo: ryoryozo via Flickr

Being mostly-vegan is certainly not easy. It doesn’t make you popular at restaurants, family gatherings or with people who love steak. But with the proper planning, it’s doable. And it’s worth doing because you know you’re living a more socially responsible lifestyle.

Or so I thought. My guiltless self-affirmation was called into question one night when my roommate looked at my dinner, a soy-based veggie burger with soy cheese plus edamame and observed, “Wow, everything you’re eating is made from soy.” Something about this declaration made me take pause. I’d been hearing a lot about soy in a negative context. As someone who loves Silk Soy about as much as I love animals, I’d chosen to ignore it. But if my diet was so soy heavy, I considered that I wasn’t as eco-friendly (or as healthy) as I thought.

The first big question I had about soy was: does it really reduce carbon emissions? A big part of my choice to be vegan was the belief that I was drastically reducing my carbon footprint in doing so. Unfortunately, I found in some cases, the answer is no. In fact, in the Amazon, where deforestation causes about 20 percent of climate change, it is frequently soy that’s causing the problem.

Fortunately, Greenpeace took the lead in pushing for a soy moratorium in Brazil that disallowed the planting of soy on deforested land and it seems to be working. In 2008, CNN reported no deforested land was used to grow soy. This year’s reports are due in a few weeks, but even if the moratorium proves successful, it doesn’t let us off the hook from being conscientious about our soy consumption, and even reducing it.

Of course, vegetarians, or humans in general, aren’t directly consuming the majority of the soy. The BBC reported that around 80 percent of the crop feeds the animals we eat. So we still need to consume less meat to decrease carbon emissions (and our indirect soy consumption), but if we want to be effective in our crusade, we can’t replace that hamburger with a nice slab of tofu, either. If we’re eating soy, we’re responsible for some of the damage.

Sadly, even organic soy products may not be as green as we think. Now, it’s pretty much confirmed that Silk Soy is using beans from Brazil and China, despite the organic label. The Organic Consumers Organization is encouraging people to boycott Silk Soy (yes, my heart is breaking) because of the way workers in these countries are treated and because even with monitoring, these soy farms still threaten the environment.

Even in the U.S., soy is grown most often industrially as a monocrop — a single crop in a giant field — meaning that it requires plenty of pesticides to maintain.  Most of the soy grown on our shores and abroad is also genetically modified, something many argue was not properly tested before being okayed by the USDA. And it is not just vegans who are noshing on it; soy finds its way into most of the products on our supermarket’s shelves these days, in the form of vegetable oil or lecithin, which is used as an emulsifier.

Beyond the environmental implications, the health implications are daunting. While the majority of scientific studies tout soy’s ability to regulate hormones for women, others discuss a connection to breast cancer.  And as for men, soy is said to lower their sperm count in large quantities.  This is all encouraging news for moderation.

In short, there is indubitably a dark side to soy. Though I love the taste of soy products, if being more careful about its consumption is the greener thing to do, I’m committed to doing it. Fortunately, there are plenty of alternatives out there.

A Slate investigation comparing the carbon footprint of soy vs. cow milk reminds us that turning soybeans into milk actually expends quite a bit of energy, as does transporting and distributing it.  We should probably be drinking less of these pre-packaged alternatives to milk, and consider making our own.  That being said, there are also alternatives to consider for health reasons.  My personal favorite is almond milk. Blue Diamond makes several delicious varieties that are fortified with calcium and high in Vitamin E. Oat milk is higher in protein, and Pacific Natural Food’s brand is packed with calcium, iron and riboflavin.

As for the soy-based veggie burger, they may be ubiquitous, but personally, I find bean-based veggie burgers to be more flavorful and less artificial tasting.  You can also reinforce eating and growing locally by making your own veggie burgers. The Savvy Vegetarian has a great all-vegan recipe for black-bean veggie burgers. And if you eat eggs, check out 101 Cookbook’s Ultimate Veggie Burger Recipe using garbanzo beans.

Another oft-overlooked source of protein is in grains. I did some research on gluten-free grains and what I found is that almost all wheat-alternatives are protein-packed and vitamin-rich. Grains such quinoa, spelt and farro offer endless options for recipes, and for health. Each packs its own unique flavor and set of nutrients, and can carry a meal while preventing the vegetarian’s “pasta-again” ennui.

Of course, the best way to ensure you are getting a good quality product is to know your farmer.  Buying soy locally, and eating it in moderation (like they do in Asia, where soy-based food is most popular) and you will be greener and healthier to boot.

Photo: portenna