Unfermented Soy vs. Fermented Soy

Tateki Matsuda

December 17, 2022

Last October, American food professionals visited fermented food producers to deepen their knowledge of Japanese fermentation culture during the “Hakko Tourism in Japan” tour campaign. As part of the tour, organizers held a tasting session where guests gave candid advice from the perspective of the American market to food product manufacturers looking to enter the United States market.

Soy has been a topic of debate in the nutrition world for many years. Current research suggests that there are benefits associated with consuming soy products regularly as part of a well-rounded diet. Soy is a plant-based protein that is high in fiber and low in saturated fat. It has been shown to have anti-inflammatory properties. It is a good source of vitamins and minerals such as magnesium, potassium, and zinc. Additionally, soy is a complete protein, meaning that it contains amino acids needed for human health. Some proclaim its endocrine-disrupting properties and risk to human health, while others tout its benefits for preventing chronic disease. As interest in plant-based diets increases, we need to have a working knowledge of soy and its potential benefits and risks.
Spy powder scooped with a wooden spoon and soy beans

Soy in Japanese culture

Japanese culture is an interesting contrast to the United States regarding soy consumption. It is estimated that the average Japanese adult consumes three or more ounces of soy per day. Yet, they have the longest life expectancy in the world. Furthermore, their healthy life expectancy is significantly higher than in the US, where adults, on average, reach age 66.

In the United States. People are consuming not just soy but hydrogenated soybean oil in ridiculous amounts. Food manufacturers use hydrogenated oils to save money, extend shelf life, add texture and increase stability. During the production of hydrogenated oil, a type of fat called trans fat is made. “Partially hydrogenated” oils contain trans fats in the final product. Partially hydrogenated oils can affect heart health because they increase “bad” (low-density lipoprotein, or LDL) cholesterol and lower “good” (high-density lipoprotein, or HDL) cholesterol.

In Japan, they’re eating specific kinds of soy. To a certain degree, Japanese people eat things like fermented and unfermented soy products, such as miso and tofu. It is obviously better than hydrogenated oil. There is a massive study published in the journal nutrients. In that case, you can look at Six studies with over 92000 participants, all epidemiological studies. They classified the Japanese staple diet as containing soy, fish, seaweed, miso, pickles, and green tea. They categorized that as the primary staples and found that even based on this data, people who adhered to that diet lived longer. It is unclear whether soy consumption directly correlates with longevity in Japan. However, the point remains that soy can provide essential nutrients and may be beneficial in a balanced diet.

How fermentation makes soy unique?

We need to pay attention to fermentation because it is an essential process in soybean production. First of all, the fermentation process changes things. Where it changes things? We don’t know entirely, but briefly speaking, the fermentation of soybeans alters the composition and structure of the beans, making them more digestible and nutrient-rich. There are also benefits to the gut microbiome.
Natto on rice with chopsticks
One of the common things people point out is that soy has estrogenic properties, such as phytoestrogens. How that translates into the human body is pretty complex, but one of the pieces that we may have to look at with specific fermented soy. For example, miso is fermented with Koji. Koji mold is a filamentous fungus used by the Japanese culture to ferment soy and rice. When it’s fermented, you have that bacterial component. You support the microbiome, which has something called the estrobolone. Estrobolone is a microbiome component that helps metabolize estrogens into good estrogens. Other lifestyle variables and diet, such as fiber, antioxidant, polyphenol intake, weight, smoking, and caffeine intake, lead to a higher amount of 16-α-hydroxy estrone, which is considered ‘The Bad Estrogen’ because its presence seems to increase breast cancer risk and has even been called a cancer-causing agent.

Japanese people also consume miso soup in general. Miso soup got broth, reasonable amounts of sodium, the fermentation process, and seaweed a lot of times in it. The seaweed has other components to it too. Japanese people consume so much in the way of seaweed with fucoxanthin, which has substantial microbiome effects and potentially positive results when it comes down to insulin modulus.

The other thing is that Japanese culture has an extremely low level of dementia, and fermented soy may be able to explain it. When you look at a study published in the Journal of Agriculture and food chemistry, the study shows that an enzyme extracted from natto may benefit heart and artery health. Nattokinase is a component of natto, fermented soybeans that may help clear out beta-amyloid plaque. Beta-amyloid plaque is a significant contributor to Alzheimer’s and Dementia. This doesn’t mean that eating fermented soy will magically clear this up. There are a bunch of other factors we have to look at with the Japanese culture’s variables, such as high fiber and active lifestyle.

Is unfermented soy unhealthy?

Tofu on green leaves on a plate on soy beans
However, some are conscious of consuming soybeans because of the “plant defense mechanism.” When it comes to a plant-based diet, people always are worried about anti-nutrients, such as goitrogens, oxalates, phytates, and phytoestrogens. Since reductions of such anti-nutritional factors by fermentation have been documented by many researchers, some allowed themselves to consume fermented soybeans such as natto and miso. So are tofu and other non-fermented soybeans not healthy?

According to “Sprouted Grains: A Comprehensive Review” from Journal of Nutrients, germination is a process of intense biochemical changes that produce new and beneficial compounds. The enzymatic activity involved in the breaking down starch reserves results in hydrolysis, forming pinholes on the surface of the grain granules. Additionally, this causes an increase in oligopeptides and free amino acids and a shift in amino acid composition. A decrease in anti-nutritional factors such as phytate, trypsin inhibitor, and tannins, alongside an increase in bioactive compounds, is also observed during germination.

I don’t think tofu is bad, as massive studies are introduced above. Different processing methods, such as gamma irradiation, dehulling, soaking, sprouting, cooking, and malting, also reduce anti-nutrients and even improve micronutrients and bioavailability. Traditional cooking methods, including washing, pilling, and soaking, have led us to healthier options. These preparation methods can produce functional foods due to the increase in nutrient content and bioavailability.

So how can non-Japanese people apply for their diet? The debate surrounding soy is ongoing and complex. However, the current body of research suggests many potential health benefits associated with consuming soy products regularly as part of a well-rounded diet. These benefits include lower levels of inflammation, reduced risk of certain chronic diseases, and improved gut health. What we should not skip important processes are traditional preparation methods. As we seek how different culinary practices affect our food intake and overall health, we may find even more reasons to appreciate these simple techniques that have been around for centuries.

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6. Hsu, R. L., Lee, K. T., Wang, J. H., Lee, L. Y., & Chen, R. P. (2009). Amyloid-degrading ability of nattokinase from Bacillus subtilis natto. Journal of agricultural and food chemistry, 57(2), 503–508. https://doi.org/10.1021/jf803072r
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Tateki "Tech" Matsuda | + posts

Tateki Matsuda is the founder of Biohacker Center Japan, holding degrees in Applied Nutrition and Sports Movement Science. As a Professional MMA fighter in the UFC and health consultant in Boston, he combines his expertise in biohacking, nutrition, and athletics to optimize performance and promote holistic wellness.