What is Fermented Soy? The Case of Natto
Fermented soy refers to any soybean-based product created through a microbial fermentation process. The most famous example containing nattokinase is natto, a traditional Japanese food made by fermenting boiled soybeans with the bacterium Bacillus subtilis natto. Natto is known for its distinct, pungent aroma, and a sticky, stringy texture that can be an acquired taste for many outside of Japan. As a whole food, natto offers a complex nutritional profile that includes far more than just the nattokinase enzyme. In addition to being a rich source of protein and fiber, natto contains naturally occurring probiotics from the fermentation, soy isoflavones, and high levels of vitamin K2. This combination means that consuming natto provides a synergistic effect from a wide range of beneficial compounds, rather than just the action of a single enzyme.
What is Nattokinase? The Specific Enzyme
In contrast, nattokinase is a potent, single enzyme extracted and purified from natto. Discovered in 1980 by Japanese researcher Hiroyuki Sumi, nattokinase is a serine protease known for its powerful fibrinolytic activity, which means it helps break down fibrin, a protein involved in blood clot formation. The enzyme is a byproduct of the fermentation process, secreted by the Bacillus subtilis natto bacteria as they interact with the soybeans. For commercial supplements, the nattokinase is isolated, purified, and freeze-dried to create a concentrated powder or capsule. Unlike whole natto, these supplements often have the vitamin K2 removed during processing to prevent any potential interference with anticoagulant medications. This makes nattokinase a highly targeted supplement for specific cardiovascular health goals.
Fermented Soy vs. Nattokinase Supplements: A Direct Comparison
| Feature | Whole Fermented Soy (Natto) | Nattokinase Supplement |
|---|---|---|
| Form | A whole food made of fermented soybeans with a sticky texture. | A purified extract, typically in capsule or tablet form. |
| Content | Contains nattokinase, vitamin K2, probiotics, fiber, soy isoflavones, and other nutrients. | Contains a concentrated, standardized dose of the nattokinase enzyme, often with vitamin K2 removed. |
| Nutrient Profile | Offers a broad range of nutrients and beneficial compounds in a food matrix. | Provides a targeted, single-ingredient dose for maximum potency of the specific enzyme. |
| Flavor/Texture | Has a pungent smell and sticky texture that can be an acquired taste. | Odorless and tasteless in capsule form, bypassing the culinary experience. |
| Standardization | Varies depending on fermentation time and method; activity is not standardized. | Sold in standardized doses, measured in Fibrinolytic Units (FU) to ensure consistent activity. |
| Vitamin K2 | Contains high amounts of vitamin K2, which supports blood clotting. | Processed to remove vitamin K2, making it a safer option for those avoiding the vitamin. |
How Nattokinase Works in the Body
The primary mechanism of nattokinase's action is its fibrinolytic activity. It works in multiple ways to support healthy blood flow and cardiovascular function. First, it directly hydrolyzes fibrin, the protein that forms the mesh in blood clots, helping to break down existing clots. Additionally, nattokinase stimulates the body's natural production of clot-dissolving agents, such as tissue plasminogen activator (t-PA) and urokinase. It also inhibits plasminogen activator inhibitor-1 (PAI-1), which is a key regulator of the fibrinolytic system. The combination of these actions results in a powerful effect on blood viscosity and circulation. Studies have also shown nattokinase to have potential antihypertensive properties, meaning it may help lower blood pressure.
Are There Different Benefits? Synergy vs. Targeted Action
The choice between consuming whole fermented soy, like natto, and taking a purified nattokinase supplement often depends on an individual's specific health goals. When you eat natto, you get the benefit of nattokinase along with other beneficial compounds, like the probiotics that support gut health and high levels of vitamin K2, which promotes bone health. However, the amount of nattokinase can vary from batch to batch. With a supplement, you receive a precise, standardized dosage measured in Fibrinolytic Units (FU), which allows for targeted therapeutic use, especially for cardiovascular support. This targeted approach is ideal for those seeking the specific blood-thinning effects of nattokinase without the other components of natto. For some, the potent and concentrated nature of the supplement is more desirable than the overall nutritional boost from the food.
Potential Risks and Important Considerations
While nattokinase is considered safe for most people, there are crucial precautions to observe. The most significant risk is for individuals taking prescription blood-thinning medications like warfarin, as nattokinase can increase their effects and lead to excessive bleeding. It is also recommended to discontinue nattokinase use at least one week before any surgical procedures, including dental surgery. Due to a lack of safety studies, pregnant and breastfeeding women are also advised against using nattokinase supplements. For individuals with soy allergies, highly purified nattokinase supplements typically do not contain the allergenic soy protein, but checking with the manufacturer is always recommended. As with any dietary supplement, consulting with a healthcare provider is essential to determine if nattokinase is appropriate for your health situation.
Conclusion
To put it simply, fermented soy and nattokinase are not the same thing. Fermented soy, particularly the food natto, is the source from which the specific enzyme nattokinase is derived. While consuming natto provides a host of synergistic benefits, supplements deliver a concentrated, standardized dose of the enzyme for specific therapeutic applications like supporting cardiovascular health. Understanding this distinction allows consumers to make informed choices based on their health needs, while also being aware of the necessary safety precautions, especially regarding interactions with blood-thinning medications.
