H for Health

The soybean has historically been at the center of considerable confusion. The media and internet abound with myths and alarmist narratives surrounding soy products, creating a landscape of misinformation. This has led to significant uncertainty, even among health professionals, regarding the true impact of soy on health and the environment.

In this article, we aim to demystify soy by examining what the latest research reveals. We will explore the health and environmental implications of incorporating soy into our regular diet, providing clarity and evidence-based insights on this contentious topic.

Why are there so many myths about soy?

The topic of soy and its health implications has been shrouded in myths and misinformation for decades. Despite over 35 years of intensive research and the publication of more than 2,000 peer-reviewed scientific articles annually, a clear scientific consensus on soy’s effects remains elusive. This ambiguity stems from several factors.

Firstly, a significant portion of the research on soy has been conducted in laboratory settings or through animal studies, particularly on mice and rats. These studies have shown that findings from such environments and subjects cannot be straightforwardly applied to humans. The confusion intensifies with the presence of phytoestrogens in soybeans. Initial animal studies published in 2001 suggested that these plant estrogens might promote the growth of breast cancer tumors in mice. However, it was later understood that phytoestrogens metabolize very differently in humans compared to rodents. Recent research has also shown that soy does NOT increase the risk of developing cancer, including breast cancer.

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When assessing research on soy’s health impacts, it is important to consider whether the studies are based on an unrealistically high daily intake of soy. Additionally, whether the studies differentiate between foods made from whole soybeans and the far less nutritious, highly processed isolates of soy protein.

Another significant source of confusion about soy comes from the influential lobbying by the meat and dairy industries. In the early 1970s, as vegetarians in the Western world began to embrace the nutrient-rich, cheaper, and environmentally sustainable soy products as meat substitutes, these industries recognized a potential threat to their profits. Consequently, they have backed research aimed at undermining soy products and have established and funded “astroturf organizations”—fabricated grassroots movements designed to mislead the public and sow doubt about soy’s health benefits. Moreover, these industries have invested heavily in anti-soy campaigns and lobbying efforts. A recent study highlighted that the meat industry benefits from at least 800 times more public support than the plant-based sector. This imbalance is partly due to the lobbying efforts of animal product producers.

Soy and Its Phytoestrogens Content

Soy is notable for its content of phytoestrogens, a group of plant-based compounds that mimic estrogen to varying extents. These compounds are not unique to soy; in fact, they are present in over 300 different plant species, making them a common component of nearly all plant-based foods. Among these, fermented soybeans and whole soybeans boast the highest phytoestrogen concentrations. However, other plant foods such as legumes, whole grains, sprouts, broccoli, onions, blueberries, nuts, seeds, and notably flaxseeds, also contain significant amounts of phytoestrogens. This underscores that many plant varieties traditionally viewed as healthful are abundant in phytoestrogens.

Isoflavones are the specific type of phytoestrogens found in soy. These compounds are structurally similar to estrogen, the primary female sex hormone, yet they interact with the human body in markedly different ways. For estrogen to exert its effects, it must attach to a specific “receptor” located on the surface of cells.

The human body houses two primary types of estrogen receptors: alpha and beta. Natural estrogen interacts with both receptors with equal affinity. Conversely, phytoestrogens show a preference for binding to beta estrogen receptors over alpha ones. This selective interaction earns them the designation “selective estrogen receptor modulators,” or SERMs. This distinction in receptor affinity is critical because it means estrogen and phytoestrogens elicit varied effects within the body, sometimes even producing contrasting outcomes. Moreover, the potency of phytoestrogens is significantly lower than that of estrogen, ranging from 1,000 to 10,000 times less effective. When phytoestrogens occupy certain receptor sites, they block the binding of natural estrogen, thereby diluting the overall estrogenic impact in the body. Beyond their role in modulating estrogen activity, phytoestrogens boast a plethora of health benefits, including antioxidative and anti-inflammatory properties, and they have been shown to inhibit the growth of cancer cells.

Soybeans can be consumed  in many ways

Soy has been a fundamental component of diets across many parts of Asia for millennia. Moreover, legumes, including soybeans, have played an essential role in “The Blue Zones”—regions globally distinguished by an unusually high prevalence of centenarians living without significant chronic illnesses. For more insights, refer to our documentary “The Blue Zones.”

Soybeans are versatile in their consumption methods. The healthiest options include natural forms like immature green edamame beans and mature, dried soybeans. Typically, mature beans are yellow, though black, brown, and even blue varieties exist. Additionally, fermented soy products such as tempeh, natto, miso, and tamari offer nutritional benefits. These are followed by slightly more processed alternatives like tofu, soy milk, and soy yogurt.

The least nutritious soy products consist of soybean oil and isolated soy protein. The production of soybean oil involves pressing oil-rich soybeans, which is then utilized in manufacturing products including margarine and soap. The by-products of soybean oil production, known as soy meal, serve as animal feed.

Isolated soy protein represents an ultra-processed soy derivative. It finds application in various food items, such as meat substitutes, breakfast cereals, and infant nutrition, produced by extracting fats and a significant portion of carbohydrates from soybeans. This process yields a by-product rich in protein, about 90%, but unfortunately, strips away many beneficial nutrients integral to soy’s health advantages.

Soy lecithin, identified as additive E 322, emerges as another product derived from soybeans. Employed as an emulsifier in numerous ultra-processed foods, it enables the mixing of fat and water, enhancing the creamy texture of desserts and dressings. However, soy lecithin’s health implications are concerning. Extracted using hexane from the residues of soybean oil production, this chemical poses risks to our nervous system. Traces of hexane found in soy lecithin, coupled with recent studies indicating its potential to exacerbate gut inflammation and compromise the integrity of the gut barrier—leading to a condition known as “leaky gut”—underscore the importance of caution. For a deeper understanding, we recommend our documentary “The gut microbiome and our health.” Hence, scrutinizing ingredient lists on food products and avoiding artificial additives, including soy lecithin, is advisable. For further exploration into the impact of ultra-processed foods, our documentary “How Ultra-Processed Foods Are Designed to Be Addictive” offers valuable insights.

Environmental Impacts of Global Soybean Production

Over the past five decades, global soybean production has experienced an exponential increase, now surpassing levels from the 1960s by more than thirteenfold. This raises the question: where is all this soy going? A mere 7% of soy production is directly consumed by humans, transformed into products like edamame beans, tofu, tempeh, soy milk, and plant-based meat alternatives. The surge in production is largely fueled by the growing demand for meat and soynean oil. Remarkably, about 77% of worldwide soy production is allocated to animal feed for chickens, pigs, aquaculture fish, and cattle raised for both beef and dairy purposes.

The conversion of soy protein into animal-based products for human consumption is markedly inefficient. It requires approximately 12 kilograms of soy to yield just 1 kilogram of beef. In the case of pork and poultry, the ratios are slightly lower, with 7 kilograms of soy for 1 kilogram of pork and 4 kilograms of soy for 1 kilogram of poultry.

Soy production exerts profound direct and indirect environmental impacts, particularly in South America. Vast expanses of land and rainforest are cleared to accommodate cattle grazing and soy cultivation. This deforestation leads to biodiversity loss and exacerbates climate change. For consumers committed to mitigating such environmental degradation, significantly reducing the intake of animal products stands out as the most effective measure.

Debunking Soy Myths

In an age where misinformation abounds, soy products have become the subject of numerous myths and unfounded scare campaigns. Contrary to these narratives, scientific research consistently highlights the health benefits of incorporating soy into our diets. Let’s clarify three of the most enduring myths surrounding soy.

1. Is Soy Hormone-Disruptive?
Claims have circulated that soy is hormone-disruptive, purportedly causing early puberty, infertility, and even the development of breast tissue in men. However, the phytoestrogens in soy, which can bind to beta-estrogen receptors in the body, do not upset hormonal equilibrium in either men or women. Detailed meta-analyses from 2021 and 2022 have conclusively shown that soy protein and phytoestrogens do not alter estrogen levels in women or testosterone and estrogen levels in men. Thus, there is no credible scientific basis for the assertion that soy disrupts hormonal function.

2. Does Soy Increase the Risk of Breast Cancer?
Soy’s phytoestrogen content has led to accusations that it could heighten the risk of breast cancer. Yet, contemporary research provides a counter-narrative, indicating that soy may actually diminish breast cancer risk. The American Institute for Cancer Research has noted that population studies consistently find no increased risk for breast cancer survivors who consume soy products. Moreover, recent findings suggest that moderate soy consumption might improve survival rates and potentially lower the risk of disease recurrence after diagnosis. A comprehensive meta-analysis in 2023 supported this, revealing that soy isoflavones could reduce the recurrence of breast cancer by 26%. The misconception that soy could elevate breast cancer risk is especially damaging, as it might deter women from consuming soy products and lead them towards animal protein sources, which studies have linked to a higher risk of breast cancer.

3. Does Soy Impact Metabolism?
There have been claims that soy negatively affects the thyroid gland’s hormone production and slows metabolism. It is crucial for thyroid hormone synthesis to maintain adequate dietary iodine. Similar to various healthful plants like different kinds of cabbage and spinach, soy contains compounds that may inhibit iodine absorption in the thyroid gland. This does not imply a need to avoid such nutritious plants but rather underscores the importance of ensuring sufficient iodine intake. Scientific evidence does not support the notion that soy consumption poses a risk to metabolic health, provided that the diet supplies adequate iodine. The recommended daily iodine intake of 150 micrograms can be easily achieved by consuming 2 sheets of nori seaweed daily or through a daily iodine supplement.

Health Benefits of Eating Soy

There are numerous health benefits associated with incorporating soy into our diet. Clinical studies have shown that soy consumption can reduce our risk of developing cardiovascular diseases and various types of cancer. A thorough meta-analysis further confirms soy’s efficacy in bolstering bone health, notably in reducing our risk of developing osteoporosis.

The gut microbiome, essential for our overall well being, benefits from soy as well. Fermented soy products, such as tempeh and miso, are particularly lauded for their positive impact on gut health. Furthermore, evidence suggests soy’s effectiveness in mitigating menopausal hot flashes, offering relief to women during this transitional phase.

Finally, the phytoestrogens in soy also appear to positively affect our skin, including boosting collagen production and thereby slowing natural age-related changes in the skin.

Drawbacks of Eating Soy

While the health benefits of incorporating soy into our diet are clear, there are a few considerations to be mindful of.

  • Allergy
    Allergies to soy are notably rare, with fewer than 0.5% of children affected. While many children outgrow this allergy, it can persist into adulthood. Individuals with a soy allergy must rigorously avoid any soy products, as even trace amounts of soy protein can provoke allergic reactions.

  • Ultra-processed Soy Products
    A significant nutritional issue with soy arises from the widespread availability of ultra-processed foods that utilize soy protein isolates. These isolates are devoid of the numerous beneficial nutrients that contribute to the health benefits of soy. It’s recommended to choose more natural soy options, such as whole soybeans, or fermented products like tempeh, natto, miso, and tamari, to maximize the health benefits while minimizing risks.

Soybeans Nutrition Facts

Soybeans are exceptionally nutritious and serve as an excellent source of protein, containing all 9 essential amino acids—those building blocks of proteins that our body cannot produce on its own. In addition, soy is a good source of fiber and various vitamins and minerals, including calcium.

Dietary guidelines in both the USA and the UK endorse the incorporation of soybeans into the diet, recognizing their nutrient-rich and health-enhancing benefits, especially when eaten as an alternative to red and processed meat.

Variety remains a fundamental principle of healthy eating, eliminating the necessity for daily consumption of all soy product varieties. The American Institute for Cancer Research suggests a balanced daily soy protein intake of 7-14 grams, equivalent to consuming 2-4 deciliters of soy milk, 200 grams of soy yogurt, 50-100 grams of firm tofu, 100-200 grams of silken tofu, or 65-130 grams of shelled edamame beans. Nonetheless, newer studies indicate that a daily intake of 15-25 grams of soy protein might be beneficial, representing 25-30% of the daily protein intake for an average person in Europe or America. This recommendation supports dietary diversity and the inclusion of proteins from various sources. is likely to provide health benefits—especially when eaten as an alternative to red and processed meat.

The inclusion of soy in one’s diet is not a prerequisite for healthfulness. For those with soy allergies or others who prefer to avoid soy, numerous alternative plant-based protein sources exist. A healthy, diverse diet, even one that is entirely plant-based, can be easily achieved without soy.

If you're considering adding soy to your dietary regimen, here are several recommendations for optimizing its health benefits:

  • Opt for soy in its whole, unprocessed forms, such as dried soybeans and edamame, which can be prepared and consumed similarly to other legumes.
  • Incorporate fermented soy products like miso, tempeh, and natto into your diet for enhanced gut health benefits, as highlighted in our documentary “The Gut Microbiome Hacks.”
  • Firm tofu is versatile; it can be sliced, diced, and cooked in various methods—fried, baked, grilled, or air-fried—until it achieves a crispy and golden texture. Given its neutral flavor, consider marinating tofu beforehand or incorporating flavor enhancers while cooking. Pre-smoked or marinated tofu are also available. Firm tofu can be scrambled or made into a spread.
  • Silken tofu, with its soft texture, is ideal for use in dressings, dips, desserts, and as an egg substitute in quiches. It’s also an excellent alternative to fresh mozzarella in tomato salads.
  • Soy milk stands out as the least processed and most nutritious among plant-based milks, offering a protein content comparable to cow’s milk. We recommend choosing calcium-fortified soy milk that’s free from oil and artificial additives, as discussed in our film “Milk, Business, Health, and Sustainability.”
  • Limit consumption of ultra-processed foods derived from soy protein isolates, such as meat substitutes, burgers, and sausages. These products, often high in oil, salt, and artificial additives, lack the beneficial nutrients found in whole soybeans. For more insights, watch our film “How Ultra-Processed Foods Are ‘Designed’ to Be Addictive.”
  • Moderate your intake of soy lecithin, an additive that recent studies suggest might exacerbate gut inflammation and contribute to “leaky gut.”
  • Steer clear of soybean oil, a concentrated fat source devoid of the proteins, fibers, and phytoestrogens that contribute to soy’s health benefits.
  • Favor organic or non-GMO soy products to minimize exposure to pesticide residues, which recent studies have shown can negatively impact the gut microbiome. For further information, refer to our documentary on the gut microbiome.

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