Nattokinase Content in Natto: What is a Fibrinolytic Unit (FU)?
The measurement of nattokinase activity is typically standardized using fibrinolytic units, or FUs. One FU represents the amount of enzyme that increases the absorbance at 275 nm by 0.01 per minute, which correlates to its ability to break down fibrin, a protein involved in blood clotting. This activity is the key metric for understanding the potential effects of both natto and nattokinase supplements.
The Standard 50g Serving
While the exact nattokinase content can fluctuate, a commonly cited figure for a standard 50g serving of natto is 1,500 FU. This level is often within the range used in various studies to observe the enzyme's potential effects, such as supporting blood pressure and circulation. It's important to recognize that this is an average, and the final FU count can be influenced by several factors.
Factors Influencing Nattokinase Levels
The amount and potency of nattokinase in natto can vary significantly based on the production and preparation methods. Here are some of the most critical factors:
- Bacterial Strain: Different strains of Bacillus subtilis natto produce varying potencies of the enzyme. The specific starter culture used during fermentation directly impacts the resulting nattokinase activity.
- Fermentation Time and Temperature: The fermentation process is a critical determinant of nattokinase activity. Research has shown that both fermentation time and temperature can be optimized to potentially maximize enzyme yield. For example, longer fermentation times can increase nattokinase activity, but excessively long periods can also negatively impact sensory qualities.
- Nutrient Availability: The specific composition of the fermentation medium, including carbon and nitrogen sources like peptone and yeast extract, can have a significant effect on the quantity of nattokinase produced.
- Processing: For nattokinase supplements, the enzyme is extracted from natto and purified. Processes like microencapsulation can be used to protect the enzyme from gastric acid, which can inactivate it. The final formulation and processing for supplements will influence their potency, which is often standardized and can be higher than the amount found in the food itself.
Natto vs. Nattokinase Supplements: A Comparison
| Feature | Natto (50g serving) | Nattokinase Supplement (Capsule) |
|---|---|---|
| Typical Nattokinase (FU) | ~1,500 FU | Often ranges from 2,000 to 4,000 FU per serving |
| Form | Fermented whole soybeans | Powder inside a capsule |
| Vitamin K2 Content | High in vitamin K2, which can potentially counteract blood-thinning medication | Typically removed during processing to potentially avoid interference with anticoagulants |
| Nutritional Profile | Rich in fiber, protein, probiotics, and other vitamins and minerals | Isolated enzyme, potentially lacking the broader nutritional and probiotic benefits of the whole food |
| Absorption | May be affected by gastric acid, potentially reducing active enzyme delivery | Often uses enteric-coated or microencapsulated capsules to potentially protect the enzyme from stomach acid |
The Broader Health Benefits of Natto
Beyond nattokinase, eating whole natto offers a host of other nutritional advantages. It is an excellent source of protein, fiber, iron, and manganese. The fermentation process with Bacillus subtilis also makes natto a natural probiotic, which can contribute to improved gut health and digestion. The synergy of these components is what makes natto a highly nutritious food, and some researchers suggest that the whole food provides a more balanced benefit than the isolated enzyme alone.
Safety Considerations and Consultation
While natto is widely regarded as a health-promoting food, and nattokinase supplements are generally considered safe, it is crucial to exercise caution in certain situations. Individuals taking anticoagulant medications, such as warfarin, should consult a doctor before consuming natto due to its high vitamin K2 content, which can potentially interfere with the medication. For those considering supplements, a discussion with a healthcare provider is also recommended to determine a suitable approach for their specific needs, especially since various levels have been used in research. You can find more information about nattokinase research from the National Institutes of Health.
Conclusion: More Than Just a Number
In conclusion, a typical 50g serving of natto delivers approximately 1,500 FU of nattokinase, a powerful fibrinolytic enzyme. However, this number is just one part of the story. The precise amount can vary based on fermentation factors, and the overall health benefit of eating natto extends far beyond just this one enzyme. The probiotic, vitamin, and mineral content of the whole food offer comprehensive nutritional support for gut and cardiovascular health. For those seeking potentially higher, more standardized levels, nattokinase supplements are available, often with the vitamin K2 removed to potentially prevent interactions with blood-thinning medications. Ultimately, whether choosing natto or a supplement, it is essential to consider the full context of its nutritional profile and consult with a healthcare provider, particularly if taking other medications.
