The consumption of soy has, for a long time, provoked intense debate.
Conflicting studies stating the dangers of soy, while others promoting it as healthy have caused confusion and the unnecessary demonization of a food that has helped certain populations, like Japanese women, thrive.
Let’s look at both sides of the discussion and consider the Ayurvedic perspective on soy to determine if it should be part of your diet.
How harmful is soy?
Critics of soy typically claim that it might cause breast cancer and thyroid issues due to its anti-nutrient and isoflavone content.
These are some reasons that provoke criticism:
- Anti-nutrients are naturally occurring compounds found in some plants, including beans and soy, to help them repel attacks from insects or other animals. However, it is more difficult to eliminate the anti-nutrients from soy than it is from other foods by just washing or cooking them.
- Phytates (phytic acid), one type of anti-nutrients, serve as the main form of storage for phosphorus in the seeds of plants. They can impede the absorption of minerals found in soy, like zinc, calcium, magnesium, and iron, and lead to nutritional deficiencies. This applies to a single meal, not overall nutrient absorption throughout the day.
- Soy has goitrogens or compounds that might inhibit thyroid function in people with marginal iodine intake. Also, genistein, the major soy isoflavone, has an estrogenic effect that can be measured in the thyroid at levels that produced dose-dependent and significant inactivation of rat and human thyroid peroxidase (TPO) in vitro.
The benefits of soy
We can now contemplate the ayurvedic perspective on soy and the reasons for its rejection from a different angle.
Anti-nutrient positive properties
First, there’s no evidence that eating moderate amounts of soy causes nutrient deficiencies; and while anti-nutrients can bind to certain nutrients, reducing the body’s ability to digest and absorb them, it is also true that they can have positive side effects.
For instance, phytates are anti-nutrients that have a potent anti-oxidation and anti-inflammatory action.
They are capable of inhibiting lipid peroxidation through iron chelation and reducing iron-related free radical generation. As this has the effect of mitigating neuronal damage and loss, phytates can help in the treatment and prevention of neurodegenerative diseases.
They can enhance lipid and carbohydrate metabolism, improve blood glucose and cholesterol levels, prevent kidney stones by avoiding the formation of calcium salt crystals, and mitigate microvascular diabetes complications.
Moreover, research suggests that phytic acid reduces proliferation of cancer cells and may contribute to cancer cells reverting to normal cells. This is an expected finding as phytates are mainly found in plant-based, high-fiber foods, which are linked to lower cancer risk.
Lastly, anti-nutrients, even in soy, not only can be reduced by fermentation and sprouting methods, but humans naturally diminish 37% to 66% of phytic acid during digestion in the stomach and small intestine.
There’s no evidence that people who have thyroid issues should avoid soy completely.
However, it is important to make sure you get enough iodine if soy is part of your diet. Iodine deficiency greatly increases soy antithyroid effects, whereas iodine supplementation is protective.
The conclusion of some studies is that widely consumed soy products may produce harm in the human population via either or both estrogenic and goitrogenic effects.
Yet, they also recognize that other elements are at play for soy to cause overt thyroid toxicity, including iodine deficiency, defects of hormone synthesis, and additional goitrogenic dietary factors.
Adverse effects of processed soy
Now, we must make a distinction between organic, minimally processed, fermented soy products, such as tempeh, miso, some tofus, soy sauce and tamari vs. highly processed, hard-to-digest soy nutraceuticals and dietary supplements.
Researchers often use the latter to conduct studies.
Using isolated, pulverized, and highly concentrated soy, unsurprisingly, leads to negative conclusions and the cancellation of soy.
These products don’t even need to be registered or approved by the FDA before production or sales, and despite widespread consumption, there is limited evidence of health benefits related to their use in well-nourished adults.
Soy nutritional supplements, soy protein isolates, soy infant formulas, and soy-based vegan meats, burgers, yogurts, and cheeses, are typically condensed active ingredients that discard the rest of the plant, or the nonactive components, and with that, ignore Mother Earth’s infinite wisdom that made soy perfect as is.
From this perspective, eating a lot of just a few isolated components of soy is problematic.
Conversely, in places where the healing effects of soy are clear, like in Okinawa, Japan, people eat whole soy, in moderate amounts, and minimally processed, as part of a whole foods diet.
Aside from their isoflavone content, soy foods are rich in nutrients, including B vitamins, fiber, potassium, magnesium, and high-quality protein.
The ayurvedic perspective on soy
According to Ayurveda, soy is sweet and astringent, with a cooling virya and a pungent after-effect.
It pacifies pitta, and might aggravate both vata and kapha, if you eat it in excess or don’t prepare it properly.
For pitta dosha, I suggest cooking it with cooling spices. Sometimes, salt and pepper is all it takes. But, I like to add cumin seeds and turmeric for a lively color.
Vata and kapha constitutions should use fermented forms of soy and warmer spices, like ginger, to render it more digestible.
Also, Ayurveda advocates for a vegetarian diet and soy can be a wonderful addition to a vegan or vegetarian approach, as it is a complete protein that contains all nine essential amino acids that the body cannot make. Just make sure that you get it organic, non GMO, and in minimally processed forms.
Soy foods are also classified as fermented or unfermented.
Fermented means that the soy food has been cultured with beneficial bacteria, yeast, or mold. This process can improve the digestibility and absorption of soy in the body, by partially breaking down soy’s sugar and protein molecules and increasing its energetics.
I recommend fermented forms like tempeh or miso if you are having a poor agni or digestive fire.
In a few words…
Soy is not a villain if, and only if, we eat it as intended by nature, and in small amounts. The ayurvedic perspective on soy also teaches us that we should cook it appropriately, using the right spices for our body type.