I first heard of the concern about men and soy about five years ago, with the publication of a tabloid-worthy piece in Men’s Health that promised to reveal “the hidden dark side to soy, one that has the power to undermine everything it means to be male.”
But before you weigh your options—what’s worse, prostate cancer or man boobs?—let me provide a little context. For millennia, after all, soy foods have been consumed in Asia, which boasts significantly lower rates of cancer and heart disease as well as increased longevity. And now, the world’s first man-bra, which comes in a perky print and protects your pecs against the effects of gravity.
Tempting as it is to go off on that tangent, back to the subject at hand. Soy is very nutrient-dense—that is, for the calories, you get lots of bang for the buck in terms of plant protein, soluble fiber, complex carbs, unsaturated fats, and minerals. This is why several generations of Westerners have made an effort to incorporate it into their diet, in the form of tofu, soy milk, infant formula, mock meats, supplements, and snack foods. In part, because it’s cholesterol- and lactose-free, soy has become an almost ubiquitous food additive as well. And why not? Preliminary research suggested that the regular consumption of soy-based foods reduces harmful LDL cholesterol, helps prevent breast and prostate cancer, eases menopausal symptoms, staves off osteoporosis, increases memory and cognitive function, and more. All good, right?
If only it were that simple. For every study linking those health benefits to soy, there’s another one that’s either maddeningly inconclusive or suggesting soy may trigger the health problems it’s thought to prevent. The controversy swirls around the naturally occurring plant compounds called phytoestrogens, which soy contains in great abundance. Phytoestrogens behave like weak estrogen in the body, and some sources claim they may increase the risk or recurrence of breast cancer, “feminize” men by lowering testosterone levels or sperm count, or disrupt childhood development.
Some detractors go further: In 2006, Jim Rutz, chairman of Megashift Ministries and founder-chairman of Open Church Ministries, published a commentary titled “Soy Is Making Kids ‘Gay.’ ” Not for the first time, let me point out that just because a theory sounds clear and logical—food contains something estrogen-like and thereby increases female hormones in the people who consume it—doesn’t mean it’s correct.
Anyhoo, where was I? I keep getting distracted. Oh, right. There are different classes of phytoestrogens, and they’re found in varying amounts in an array of plants, including staple foods (among them, garlic, onions, spinach, apples, and pears) and medicinal herbs such as red clover, black cohosh, alfalfa, and turmeric. According to “The pros and cons of phytoestrogens,” a well-documented summary published in Frontiers in Neuroendocrinology, “one major class [of phytoestrogen] is the lignans, which are components of plant cell walls and found in many fiber-rich foods such as berries, seeds (particularly flaxseeds), grains, nuts and fruits.” Will eating those make men develop breasts too?
But most phytoestrogens are phenolic compounds such as the group called isoflavones, found in berries, wine, grains, nuts, and legumes—especially soybeans. (The isoflavone content of various foods, both whole and processed, can be found in a number of online databases, including this one from the U.S. Department of Agriculture.) Soy isoflavones can bind to estrogen receptors inside cells, exerting hormonal effects on mammals. Of intense interest to researchers is that the binding may be tissue-selective, meaning that isoflavones can mimic the effects of estrogen in some tissues and block the effects of estrogen in others. To further cloud the good/bad debate, isoflavones such as resveratrol (found in red grapes and wine) and genistein (soy) are powerful antioxidants.
Isoflavone content can vary within the same group of foods. The amount in soy products, for instance, depends on factors such as local and seasonal differences in the raw soybeans, the type of soybean used, the soil it’s grown in, and the processing method. The College of Agricultural Science at Penn State has a handy chart of the average isoflavone content of soy foods: 100 grams, or about 3.3 ounces, boiled soybeans have 54 milligrams, tofu has 28 milligrams, and soy milk, which is almost as rich in protein as cow’s milk and has less fat and zero cholesterol, has 10 milligrams. The level of isoflavones in soy milk can also vary by brand.
The takeaway? If you’re not confused and uncertain about the health effects of soy foods, then you must not be reading carefully. Inconsistent findings are complicated by the fact that much of the work is underwritten by industries with considerable vested interests. It’s also worth noting that a large percentage of the many thousands of studies published in peer-reviewed journals were carried out on animals often given far greater amounts of isoflavones than any human would ever consume in comparison. Any experienced researcher will also tell you that designing and carrying out a study, on a food or a single component within a food, then interpreting the results, is exceedingly complex. As far as soy is concerned, where the answer ultimately lies is anyone’s guess and will likely take into account age, general health, level and duration of consumption, and even the makeup of an individual’s gut microflora (bacteria that live in the intestines).
My feeling is that you can obtain all the nutrients in soy milk from other sources, so if you don’t want to drink it for whatever reason, then don’t. If you enjoy it, though, then by all means work it into a varied, balanced diet. Because there’s so much G.M. soy in the food chain, you might want to choose a brand that’s certified organic.
But try to avoid the more-is-better approach. If your usual breakfast is a soy milk smoothie or soy milk over cereal with added isoflavones, or if your favorite hors d’oeuvre is a handful of warm boiled edamame, then watch your daily consumption of soy-based snacks or supplements and don’t overdo it.
Now, back to that Japanese man-bra. I love that print! I wonder if it comes in women’s sizes?