Few foods spark as much debate as soya. Once celebrated for its high-quality protein and versatility, soya has become the subject of persistent myths, particularly regarding its impact on hormones. But where did all this confusion begin?
Much of it stems from studies conducted on animals like mice, parrots, and rats—creatures whose physiology is not suited to raw soya diets. These findings, while intriguing, are hardly applicable to human health. Another source of misunderstanding comes from a widely publicized case involving two men who consumed an extraordinary 12 or more servings of soya daily for an entire year. Unsurprisingly, this extreme and unbalanced dietary choice led to health issues, including enlarged breast tissue and reduced libido.
But let’s pause for a moment: why would anyone eat over a dozen servings of soya in a day? A truly nourishing diet should be vibrant and diverse, filled with a variety of plant-based foods that not only meet our nutritional needs but also delight the senses.
Once these men returned to a balanced, varied diet with normal soya consumption, their health returned to normal. Unfortunately, these isolated cases were sensationalized, instilling unwarranted fear in men about enjoying soya as part of their meals.
The truth is, soya can be a wholesome and delicious part of a well-rounded diet when enjoyed in moderation—just like any other food. Let’s leave the fear behind and embrace the beauty of balance in the way we nourish ourselves.
Soya protein
Soya isn’t essential in a diet, but including it can make meeting protein needs both easy and convenient. It’s a wonderful source of the amino acids lysine and tryptophan, offering versatility and nutrition. While soybeans shouldn’t replace other beans and legumes, they are uniquely nourishing. Unlike their legume cousins, soybeans are higher in protein and healthy fats, yet lower in carbohydrates. Interestingly, the type of carbohydrate in soya is one that humans cannot digest—making it a valuable food for nourishing our gut’s healthy bacteria.
Soya protein is exceptionally digestible, and its quality is comparable to that of animal-based proteins. In fact, when ranked based on amino acid profiles and digestibility, soya takes the top spot among plant proteins. It’s also brimming with nutrients such as calcium, iron, potassium, and folate, all essential for vibrant health.
Soya and anti-nutrients
Though soya contains phytates and oxalates—compounds known to inhibit mineral absorption—the calcium in tofu and fortified soya milk is absorbed just as effectively as calcium from cow’s milk. And the iron in soya, present as ferritin, is well-absorbed and unaffected by phytates, making it an excellent source of plant-based iron.
Soya’s unique nutritional qualities, paired with its versatility, make it a delightful addition to a balanced, plant-focused lifestyle. It’s a beautiful way to nourish your body while enjoying the many forms it can take—be it tofu, tempeh, soya milk, or beyond.
Isoflavones and oestrogen
One of the most talked-about questions surrounding soya revolves around its isoflavones and their relationship with oestrogen. Let’s take a closer look.
Soya products are naturally rich in phytochemicals called isoflavones, often referred to as phytoestrogens. These compounds can bind to the same receptors in our cells that human oestrogen binds to, which has led to the mistaken belief that they act exactly like our oestrogen. The reality, however, is much more nuanced—they are not the same.
Isoflavones belong to a fascinating group of compounds known as selective oestrogen receptor modulators. This means they are selective in how and where they bind, making their behaviour quite different from that of human oestrogen. Our cells have two types of oestrogen receptors—alpha and beta. While human oestrogen binds to both, isoflavones primarily bind to the beta receptor. Depending on the type of tissue, isoflavones can act as weak oestrogens, anti-oestrogens, or even have no effect at all.
Intriguingly, evidence suggests that these compounds may have anti-cancer properties. For example, in reproductive tissues like the breast and uterus, isoflavones tend to act as anti-oestrogens, while in bone-forming cells, they behave as weak oestrogens—a beneficial effect that can support bone health.
Ultimately, the research tells us that soya consumption may either protect against breast cancer or have no impact on risk, with no evidence of harm. The most benefit seems to come from moderate consumption—around two servings per day—of traditional soya foods such as tofu, tempeh, or soya milk.
When enjoyed mindfully, soya can be a nourishing and supportive part of a balanced diet, offering benefits that align beautifully with a life of wellness and vitality.
It’s important to note that isoflavones are metabolized differently from person to person. One of the most fascinating compounds derived from consuming soya is equol, which is produced by certain gut bacteria and is remarkably beneficial for our health.
However, not everyone’s gut microbiome has the ability to produce equol. Studies show that only about 25% of Western populations have the specific gut bacteria needed, while in Asian populations, this number rises to around 50%. Interestingly, there’s evidence to suggest that vegetarians are more likely to produce equol compared to meat-eaters, highlighting the dynamic relationship between diet, gut health, and our body’s ability to unlock the full benefits of soya.
This beautifully intricate connection between soya, gut bacteria, and health underscores just how unique our bodies are—and how mindful dietary choices can nurture our well-being.
The benefits of soya
So, what are the true health benefits of soya?
Soya is wonderfully supportive of heart and vascular health, thanks to its ability to lower LDL cholesterol—the type that can contribute to heart disease. Beyond that, isoflavones in soya may also have a direct, protective effect on the health of our arteries, promoting better circulation and overall cardiovascular well-being.
Can men eat soya?
Despite the lingering misconception that soya isn’t beneficial for men, the reality is quite the opposite. Research shows that men who consume higher amounts of soya are about 30% less likely to develop prostate cancer—a powerful testament to its protective potential.
Soya and cancer risk
One of the most frequently asked questions—does consuming soya reduce the risk of breast cancer?
For years, the historically low rates of breast cancer in Asian women have led researchers to explore whether something in their diet offers protective benefits. Studies now suggest that soya is not only harmless when it comes to breast cancer risk, but it may even be beneficial. Research has shown that soya consumption does not negatively impact key indicators of breast cancer risk, such as breast cell proliferation or tissue density.
In fact, the World Cancer Research Fund International suggests that soya may even enhance survival in women who have had breast cancer. Additionally, there is compelling evidence that young girls who consume soya early in life may have a lower risk of developing breast cancer later on.
This growing body of research highlights soya’s potential as a gentle yet powerful ally in women’s health—a beautiful example of how the foods we nourish ourselves with can play a role in long-term well-being.
Does soya interfere with thyroid function?
Soya contains natural compounds called goitrogens, which are also found in other wholesome foods like cruciferous vegetables, millet, and certain herbs. While goitrogens can influence thyroid function, they only seem to pose a concern when iodine intake is insufficient. Iodine is an essential nutrient for thyroid health, and as long as you’re getting enough, soya should not be a problem.
In fact, the European Food Safety Authority has dismissed concerns about soya isoflavones affecting thyroid function, reinforcing that soya can be safely enjoyed as part of a balanced diet.
For those with hypothyroidism who take thyroid medication, it’s advisable to consume soya away from the time of taking the synthetic thyroid hormone, as soya may reduce its absorption.
How much soya should we eat?
Enjoying 2 to 3 servings of soya foods per day is perfectly balanced and beneficial. Lovely options include:
- ½ cup of tofu, silken tofu, or tempeh
- 1 cup of soya milk
- 1 tablespoon of miso
- ½ cup of cooked soybeans or edamame
While soya isn’t an essential part of a diet, there’s also no reason to avoid it. If you enjoy it, soya can be a delicious, nourishing, and versatile addition to your meals, offering wonderful health benefits along the way.