What's The Deal with Soy?
Soy comes from the legume family and is widely used in vegan dishes - including many of our PUL recipes. It's a fantastic source of protein, and an easy way for vegans to reach their recommended intakes. However, it doesn't come without controversy. We've received several questions about soy related to nutrition and health, we'll delve into some of them in this article to sort out the reliable science from the misunderstood information.
Soy provides a range of beneficial nutrients:
+ Protein: soy is a complete protein, meaning it contains all 9 essential amino acids needed by humans.
+ Healthy Fats: containing primarily monounsaturated and polyunsaturated fats. Learn more on fats here.
+ Calcium: The consumption of soy foods has been observed to maintain bone density and potentially decrease fractures in post menopausal women. Tofu provides about 375mg of calcium per 100g (if it's a brand that's calcium-set, such as those made with calcium sulphate). Learn more about calcium here.
+ Iron: using tofu as example again, it provides about 5mg of iron per 100g. Learn more about iron here.
+ Isoflavones: a type of phytoestrogen with antioxidant properties, which may be beneficial in fighting cancer.
Types of Soy Products
Tofu: this is likely the first soy product most people think of right away. Tofu is a widely available and versatile way to incorporate soy into sweet or savoury recipes. Here are a few examples:
» Savoury: Tofu Tapenade Sandwich or this Spicy Garlic Wok Noodles with Stir-fry Veg & Tofu
» Sweet: Mousse au Chocolat
Tempeh: tempeh differs from tofu in that it is fermented and it uses the whole soybean -- which means a higher protein content -- compared to tofu. Like tofu, it takes on the flavour of any marinade or sauce used.
» Try this Soba Noodle Bowl with Shiitake Mushrooms & BBQ Tempeh
Edamame: these are the immature soybeans in the pod. They are often boiled or steamed and served with salt.
» Deconstructed Sushi Bowl with Sweet Sesame Dressing
Fortified Soy Milk: another popular soy-based product - use it in your morning coffee, chai, smoothies, baking or simply enjoy a glass on its own. 1 cup provides 7g of protein and 2g of fibre. Soy milk can vary in sugar based on sweetness level - aim for the "unsweetened" or "original" varieties vs. the "vanilla" or "chocolate" varieties.
» Try this Speedy & Creamy Steel Cut Oats
» Or this Chocolate & Hazelnut Milkshake Smoothie
Fun fact: one reason why we use soy milk more often than other plant-based milks at the PUL headquarters is because it offers significantly more protein per cup than almond, oat or rice milk.
Read more about plant-based protein in this PUL article.
Soybeans: you can purchase roasted soy nuts to pack into lunches as a crunchy snack - but ensure that they are roasted. Raw soybeans are not properly digestible.
» 1oz (30g) contains 11g of protein, 6g of fat & 2.5g of fibre.
Miso: this is a traditional Japanese seasoning/paste made by fermenting soybeans with salt and koji. It has a unique flavour profile (and probiotics - bonus) from the fermentation process is used in many Asian dishes - including miso soup. Keep in mind that miso can be quite salty, though it's not usually used in large amounts.
» Try this Nourish Bowl with No-cook Miso Gravy
Soy Protein Isolate: we mentioned this one in our protein article. Many vegan protein powders contain soy protein isolate which provide around 23g of protein in just 1oz (30g)! With that said, we recommend getting protein from food sources first. So leave this one for days where convenience is a priority or if your needs are higher than what you can manage to eat from foods alone.
Soy-based Meat Substitutes: these can come in the form of soy burger patties, sausages, nuggets and so forth. Many contain a soy-based product called "textured vegetable protein (TVP). While tasty, they are quite processed and as a result come with excess amounts of saturated fats and sodium. Again, aim for the whole food sources most often, and leave these foods for the days where you're in a pinch or are absolutely craving those "nuggets" (we all know those days).
Peanut Butter Jelly Smoothie Bowl
Now, let's sort through some of the common controversial questions...
Is it Safe for Men to Eat?
Men commonly ask about the effects of soy on their hormone levels, prostate health and whether or not they will develop "male breasts". This stems from the presence of phytoestrogens (more specifically isoflavones), which are plant derived estrogens found in a variety of foods, most notably soy. The phytoestrogens in soy do not appear to have any effect on hormone levels under moderate intake (2-3 servings per day) and they have not been shown to affect sexual development. With regards to prostate health, the consumption of soy foods has actually been associated with a reduction in prostate cancer risk in men.
Does Soy Cause Breast Cancer?
Soy does not appear to have a cause-and-effect relationship with cancer. In fact some studies have shown the opposite. We mentioned the protective relationship for prostate cancer, but what about breast cancer? Many epidemiological studies have displayed the potentially protective powers of soy foods against breast cancer. A meta-analysis of 18 epidemiological studies found that soy intake is associated with a small reduction of breast cancer risk but even they note that this information should be taken with caution. This is because there are confounding elements at play such as genetics, physical activity, population of interest. For example, many of these studies were done in Asian populations, compared to Western populations.
For those who are already diagnosed with breast cancer, or are in remission, it was shown that soy food consumption was significantly associated with decreased risk of death and recurrence for certain types of breast cancer.
Soy & Deforestation
It's true that soybean plantations are unfortunately responsible for a great deal of deforestation, primarily in South America. There is a great threat to wildlife and biodiversity. However, this doesn't mean you need to cut out soy products altogether. Let's look at the numbers: the vast majority of soy grown -- around 85% -- is either fed to livestock or is turned into soybean oil for a variety of food and non-food products. Only about 6% is used directly as human food (in the forms we mentioned above). We have to pick our battles and do the best that we can in our own circumstance. We believe that by limiting your intake of meat, you can make a larger impact on reducing this footprint both directly and indirectly than you would by cutting soy products out altogether.
Vegan Pho » Vietnamese Noodle Soup
What about Soy & Heart Health?
Evidence has supported the role of soy protein and the reduction of certain serum lipids, such as low density lipoprotein (LDL) cholesterol, that are related to cardiovascular disease. There is no current observed change on HDL, triglyceride or blood pressure levels. This means that soy-based foods can be included in a balanced heart-healthy diet that support cardiovascular health.
Should I Avoid Soy if I have Thyroid Issues?
While soy does not cause hypothyroidism, it's been noted that soy isoflavones may somehow occupy or take up the iodine needed to make thyroid hormones important for thyroid function. It's theorized then, that those with hypothyroidism may not necessarily need to stop consuming soy products, but instead increase their iodine intake to ensure adequacy. Seaweed is a fantastic source of iodine, although depending on where you live, your table salt may be iodized as well. Consult with your physician and dietitian for individualized recommendations. Research is every-growing and all of the information has yet to be uncovered.
Should I be Concerned About GMO Soy?
The topic of GMO is perhaps even more controversial than the topic of soy itself. It is a whole other matter unto itself and deserves a dedicated nutrition article (we've got it on our list). There is no evidence to show that genetically modified foods cause allergies or a resistance to antibiotics. Using Canada as an example, GM foods available are considered safe to eat as per safety assessments. Ultimately, it is your choice. Check the rules and regulations in your own country surrounding labelling and safety assessments. If you are concerned about eating GM foods, you can call companies to see if they use GM foods, look for "GMO-free" labelling, or buy organic foods. More research is needed in this field and we look forward to creating an article on this topic in the future.
Fun fact: In Canada, if a food item is labelled as "organic" it is automatically non-GMO. However, if something is labelled as "non-GMO" it is not necessarily organic.
Brown Rice & Green Bean Miso Salad
The Bottom Line
Moderate Intake: eating 2-3 servings of soy products per day is known to be safe and potentially beneficial.
Men's Health: soy consumption does not have any known effect on hormone levels or sexual development and may even have a protective role in reducing the risk for prostate cancer.
Women's Health: for those who are already diagnosed with breast cancer, or are in remission, it was shown that soy food consumption was significantly associated with decreased risk of death and recurrence for certain types. Overall, soy supplements are not recommended, but a moderate intake of whole foods is acceptable.
Other Medical Concerns: more research is needed on soy with regards to other cancers, thyroid function, heart health and so on. It is important to consult with your physician and dietitian for individualized recommendations.
Whole Food Sources: aim to eat whole food sources of soy (edamame, soy nuts, tempeh, tofu), & processed products (protein powders and soy-based meat substitutes) less often. Soy supplements are not recommended.
Soy is a Common Allergen: we mentioned the benefits of soy in this article. But keep in mind that soy is a common allergen. If you are having adverse effects when you eat soy-products, consider visiting a physician.
Be Critical of Research: a lot of research surrounding soy can be misunderstood and sensationalized for a good news story. Be critical and diligent of the magazine articles and online health site articles you read. Look for citations and do your own research! This goes for any nutrition-related topic.
Mousse au Chocolat with Silken Tofu
(1) Brenda Davis and Vesanto Melina. "Becoming Vegan: the Complete Reference on Plant-Based Nutrition." Becoming Vegan: the Complete Reference on Plant-Based Nutrition, Book Publishing Company, 2014, pp.105-106.
Psst: » Find this book in our shop! Choose between the comprehensive edition or the express edition.
Want To Learn More?
Read our previous nutrition article called PROTEIN » an uncomplicated guide for vegans.
What About You?
What are your favourite soy foods? Let us know in the comment below or share your recipes with us on Instagram with the hashtag #pickuplimes.
❤ Written by: Mitra (PUL Assistant and Dietetics Student) & Sadia