Natto: The Power of Fermented Soybeans
Natto is a traditional Japanese food made from fermented soybeans. While it is celebrated for its health benefits, including high vitamin K2 and nattokinase content, it's natural to question the optimal daily amount. For most healthy individuals, a single packet (around 40-50 grams or 1.5-1.8 ounces) is a safe and beneficial daily portion. This amount provides a substantial dose of probiotics, vitamin K2, and nattokinase without causing adverse effects for the average person. Regular, moderate consumption is a common practice in Japan, contributing to a healthy diet rich in fermented foods.
Recommended Daily Serving Size
- One Packet (40-50g): The standard serving size in Japan, often served with rice for breakfast. This portion delivers a concentrated dose of nutrients. For example, a 50g serving can contain 11% of the daily calcium needs and a significant amount of vitamin K2.
- One to Two Tablespoons: For those new to natto's strong flavor and texture, starting with a smaller amount, like a teaspoon or tablespoon, is a sensible approach. You can gradually increase your intake as you become accustomed to it.
- Listen to your body: While a standard recommendation exists, individual needs can vary. Pay attention to how your body responds and adjust your intake accordingly.
Potential Risks of Overconsumption
Although natto is healthy, consuming it in excess, especially when starting out, can lead to side effects. The high fiber content may cause digestive issues in some individuals. More importantly, its high vitamin K content can pose a risk for specific groups.
High Vitamin K2 and Nattokinase: Natto is one of the richest sources of vitamin K2 (MK-7) and also contains the enzyme nattokinase. Both of these have an effect on blood clotting, albeit in different ways. Nattokinase thins the blood by breaking down fibrin, while vitamin K is essential for the production of clotting factors. While these properties are generally beneficial for cardiovascular health, they can become a concern in high doses, especially when combined with certain medications.
- Digestive Discomfort: A sudden increase in fiber can lead to gas, bloating, or diarrhea. Starting with a small serving allows your digestive system to adapt.
- Medication Interference: High intake of vitamin K can counteract the effects of blood-thinning medication like warfarin. Anyone on these medications should consult a doctor before incorporating natto into their diet.
- Blood Clotting Concerns: For individuals with pre-existing bleeding disorders, excessive natto consumption could pose a risk due to its blood-thinning properties.
Natto vs. Nattokinase Supplements
It's important to distinguish between eating natto as a food and taking nattokinase supplements. While both contain the same enzyme, their effects can differ significantly. Supplements can contain a more concentrated, standardized dose of nattokinase, whereas the amount in food can vary.
| Feature | Natto (Food) | Nattokinase Supplements |
|---|---|---|
| Form | Fermented soybeans | Concentrated pill, powder, or capsule |
| Standard Dose | Not standardized; content varies by batch | Standardized in Fibrinolytic Units (FU) |
| Key Nutrients | Probiotics, fiber, vitamin K2, protein, minerals | Primarily nattokinase; often has vitamin K2 removed |
| Risk Profile | Generally low risk for most, interacts with blood thinners | Higher risk of interactions due to concentrated dose; consult doctor |
| Purpose | Overall dietary health, gut health | Targeted cardiovascular support |
| Consideration | Safer for daily consumption in moderate amounts | Requires medical supervision, especially for long-term use |
Who Should Be Cautious?
While natto is a superfood for many, certain individuals need to exercise caution. Pregnant or breastfeeding women, and those with soy allergies, should avoid or limit intake. People with thyroid issues should also be mindful, as some compounds in soy can be goitrogenic. Always consult a healthcare professional, especially if you have an underlying health condition or are taking prescription medication.
Conclusion
For most people, a daily serving of 40-50 grams of natto is a safe and effective way to benefit from its nutritional profile, which includes probiotics, vitamin K2, and nattokinase. Starting with smaller portions is wise if you are new to this unique food. For those with specific health concerns, particularly individuals on blood-thinning medication or with soy allergies, medical advice is essential. The key takeaway is that moderation is the best approach for long-term, safe consumption, allowing you to reap the rewards of this Japanese superfood without risk.
Authority Outbound Link: Learn more about the benefits and preparation of natto at Everyday Health
