The Scoop on Soy
By Chelsea Fisher
Controversy, confusion, and cancer have come to surround soy in recent years. Studies have found that, depending upon who conducts or is included in any given study, the legume can inhibit, aid, or have no effect on cancer growth, leaving many of us wondering whether we should stay away from soy products or eat them religiously.
According to the American Institute for Cancer Research (AICR), the American Cancer Society, and the Mayo Clinic, we should neither banish nor gobble up soy. Moderate amounts of a soy product -- about three servings a day – isn’t likely to have harmful effects, and can be a great, economical way to consume plant-based protein and other nutrients. Soy provides essential amino acids, fiber, vitamin C, thiamin, folate, calcium, magnesium, phosphorus, potassium, and manganese.
However, physicians may advise against eating soy and soy-based products, especially for women who have hormone-positive breast cancers and take tamoxifen or aromatase-inhibitor medicines. That’s because soy contains phytoestrogens, plant hormones that are thought to potentially mimic estrogen found in our bodies.
Phytoestrogens were discovered in the 1930s and have since been studied for their potential to reduce the risk of breast, prostate and uterine cancers, all of which can be hormone-triggered. Because phytoestrogens are a much weaker form of the hormone than our bodies create naturally, scientists have speculated that a diet rich in the compounds from a young age can actually protect against certain types of cancer, possibly by replacing the stronger estrogens in our systems with the weaker ones from plants. Others have also suggested that diets rich in phytoestrogens can potentially harm postmenopausal women. Neither of these claimed effects has been explicitly proven in humans.
Phytoestrogens are found in a number of plants, including cereal brans, legumes, and sesame seeds, but they are highest in flaxseeds and soy. The specific type of phytochemicals found in soy and soy-based products are called isoflavones. Though some animal studies have shown that extremely high levels of soy isoflavones can promote breast-cancer development, this has never been found in humans.
For women, specifically breast-cancer survivors or and those wary of the plant’s possible relationship to that cancer, soy appears to be safe if consumed in moderation. According the AICR, a 2010 study of Chinese breast-cancer survivors found that eating large amounts of soy was linked to a lower recurrence and death rate. Population-based studies comparing Japanese women, who have high levels of soy intake, to American women, who do not, find that there is actually a lower rate of hormone-based breast cancers among the Japanese. However, this finding may be a result of the mostly plant-based diet in Japan and the fact that Japanese women eat soy products from infancy.
As for men, studies have found that a normal intake of soy isoflavones will not have negative effects on male hormone levels and may help lower blood levels of prostate-specific antigen (PSA), which at high concentrations can indicate prostate cancer.
To get just the right amount of soy in your diet, remember that soy comes in many forms, such as tofu, soymilk, miso, soy nuts, tempeh, soy yoghurt, soy ice cream, and soy flour. One serving works out to be approximately half a cup of tofu or tempeh, a cup of soymilk, half a cup of cooked edamame, or an ounce of soy nuts.
Take note that soy is also found as an additive in many processed foods, including meat, meat alternatives, and snacks. The AICR recommends watching out for added soy in processed foods and avoiding soy supplements to make sure you do not end up with an overabundance of it in your diet.
Soy comes in many forms. Soy milk, tofu and fermented products like tempeh and miso are just some of them. Soy products are great for those who are lactose intolerant, but try other lactose-free alternatives as well as soy so as not to overload. When buying soymilk, look for the plain unsweetened varieties; the flavored ones tend to be high in sugar. Tofu comes in different consistencies, such as silken, medium, firm and extra firm. Choose a consistency that fits your needs or the demands of the recipe. Silken tofu can be really useful if treatment makes food hard to swallow. Blended into soups and smoothies, smooth silken tofu softens texture while adding a great protein boost. Medium, firm and extra firm tofu are excellent for baking or stir-frying. Tempeh is a great meat alternative, while miso adds great flavor to soups and stews.
Baked tofu will take on the flavor of any spice and always makes a delicious dish. Use firm tofu in CFYL’s Lemon-Soy Baked Tofu, a simple recipe with a tasty marinade. For a treat, try our Orangey Tofu Chocolate Pudding made with silken tofu, semisweet chocolate and orange zest. Miso is always delicious try making our Pumpkin Miso Soup. If you’ve never tried tempeh before, it’s worth a shot. Its texture is heartier and denser than tofu, but it will also take on other flavors in the dish. Try our Thai-Style Tempeh Curry. Don’t forget simple edamame. You can usually find frozen soybeans year-round. They just need a quick blanching and a little sea salt to make a great appetizer or snack.