What does eating natto every day do?

December 15, 2025 •

5 min read

Japanese research from the National Cancer Center found that high consumption of natto, a traditional fermented soybean food, is linked to lower mortality rates. Many people wonder, however, exactly what does eating natto every day do for their long-term health and well-being.

Quick Summary

Daily consumption of natto, a fermented soybean dish, can significantly enhance gut and heart health, strengthen bones, and support the immune system due to its rich vitamin K2, probiotic, and nattokinase content. It is generally safe but requires caution for those on blood thinners.

Key Points

Rich in Probiotics: Daily natto intake introduces beneficial Bacillus subtilis bacteria to the gut, improving overall digestive health and potentially boosting immunity.
Heart Health: The nattokinase enzyme in natto can help dissolve blood clots and lower blood pressure, promoting a healthier cardiovascular system.
Stronger Bones: Natto is a potent source of Vitamin K2, which activates proteins that regulate calcium, helping to strengthen bones and potentially reduce age-related bone loss.
Medication Interaction: Individuals on blood-thinning medication like warfarin must consult a doctor before adding natto to their daily diet due to its high vitamin K2 content.
Acquired Taste: Natto has a sticky texture and pungent smell, making it an acquired taste. It can be mixed with other foods or used in powdered form to ease into daily consumption.
Highly Nutritious: A daily serving provides a wealth of protein, fiber, vitamins, and minerals, making it a nutrient-dense addition to any diet.

The Powerful Health Effects of Daily Natto Consumption

Natto is a traditional Japanese food made from fermented soybeans. It has a sticky, stringy texture and a pungent aroma that many describe as an acquired taste. For centuries, it has been a staple in the Japanese diet, particularly at breakfast, and is now gaining recognition globally as a superfood. The fermentation process, which uses Bacillus subtilis bacteria, is responsible for its unique qualities and many of its health benefits. Daily intake can have profound effects on the body, from the digestive system to cardiovascular and bone health.

Improved Gut Health and Digestion

One of the most immediate effects of eating natto daily is on gut health. As a fermented food, natto is packed with probiotics, which are beneficial bacteria that help balance your gut microbiome. A healthy and diverse gut flora is crucial for many aspects of physical and mental health. Consuming natto regularly has been shown to improve digestion and alleviate symptoms like constipation and bloating. The fermentation process also breaks down some of the anti-nutrients found in soybeans, making the food more digestible and its nutrients more readily absorbed by the body.

Probiotics: The Bacillus subtilis in natto can survive the trip through the digestive system to populate the gut with beneficial flora.
Fiber: Natto is an excellent source of dietary fiber, with a single serving containing a significant percentage of the daily recommended intake. This fiber supports regular bowel movements and adds bulk to stool.
Reduced Inflammation: A healthy gut microbiome supported by probiotics can help reduce gut inflammation, which is linked to numerous chronic diseases.

Enhanced Cardiovascular Function

Daily natto consumption is widely associated with better heart health, a benefit often attributed to the enzyme nattokinase and high vitamin K2 content.

Nattokinase: This potent enzyme is produced during the fermentation process and has fibrinolytic properties, meaning it helps dissolve blood clots. This can lead to improved blood flow, reduced blood pressure, and a lower risk of stroke and heart attack.
Vitamin K2: Natto is one of the richest food sources of vitamin K2, particularly the highly bioavailable MK-7 form. Vitamin K2 helps prevent arterial calcification by directing calcium out of arteries and into bones, where it is needed. High intake of K2 is linked to a lower risk of heart disease.
Fiber and Fat: The fiber and polyunsaturated fats in natto can help lower LDL ('bad') cholesterol levels, further benefiting cardiovascular health.

Stronger Bones and Slower Bone Loss

For those concerned with bone health, especially postmenopausal women, eating natto daily can be highly beneficial. Natto's unique combination of nutrients helps improve bone mineral density and reduce fracture risk.

Vitamin K2 Activation: Vitamin K2 activates proteins, such as osteocalcin, which are essential for binding calcium to bones and teeth. Studies have shown that regular natto intake can significantly reduce the rate of bone mineral density loss in postmenopausal women.
Calcium and Magnesium: Natto contains decent amounts of calcium and magnesium, two minerals vital for bone strength.
Study Findings: Population studies in Japan have shown a correlation between higher natto consumption and better bone mineral density in both men and women, suggesting a protective effect against osteoporosis.

Potential Risks and Considerations

While largely beneficial, daily natto intake comes with some considerations:

Blood Thinners: Because of its high vitamin K2 content, natto can interfere with the effectiveness of certain blood-thinning medications, such as warfarin. Individuals on these medications should consult a healthcare provider before making natto a daily habit.
Soy Allergies: As a product of soybeans, natto should be avoided by individuals with soy allergies. While fermentation may reduce some allergens, it is not considered a safe alternative.
Thyroid Function: Soy is a goitrogen, which can affect thyroid function in large amounts. While unlikely to be an issue for healthy individuals, those with impaired thyroid function should be mindful of their intake.
Gastrointestinal Distress: Sudden, daily high-fiber intake can cause initial digestive discomfort like gas or bloating in some people. It is best to start with small portions and gradually increase them.

Natto vs. Other Fermented Foods


Feature	Natto (Fermented Soybeans)	Yogurt (Fermented Dairy)	Kimchi (Fermented Cabbage)
Source	Soybeans	Milk	Cabbage, other vegetables
Key Probiotic	Bacillus subtilis	Lactobacillus, Bifidobacterium	Lactobacillus plantarum
Noteworthy Enzyme	Nattokinase	Lactase (in some)	None
Vitamin K2 Content	Exceptionally high	Low to moderate	Low
Vitamin B12	Very low	High (animal source)	Low
Texture	Sticky, stringy, slimy	Smooth, creamy	Crunchy
Flavor Profile	Pungent, umami, earthy	Tangy, mild	Spicy, sour

How to Incorporate Natto into Your Daily Diet

For beginners, getting past the strong aroma and sticky texture can be a challenge. Here are some ways to make daily natto consumption more palatable:

The Traditional Way: Serve a small portion over hot steamed rice. The heat helps soften the texture. Add the included soy-based tare sauce and a dash of karashi mustard to cut the flavor. Toppings like chopped green onions can add freshness.
Mix with Other Foods: Blend natto into scrambled eggs, soups, or rice bowls to help mask the texture. A spoonful added to a salad or mixed with avocado can also work well.
Natto Toast: For a quicker option, spread it on toast and top with mayonnaise or cheese before toasting. This creates a different texture and flavor profile.
Dried or Powdered Natto: If the texture is still a barrier, freeze-dried or powdered natto can be added to many dishes, like dressings or smoothies, without the stickiness. This allows you to reap many of the benefits without the sensory experience.

Conclusion

Consistently eating natto every day can offer a wide array of scientifically supported health benefits, primarily centered around its powerful probiotic content, the enzyme nattokinase, and its unparalleled richness in vitamin K2. The positive effects on gut health, bone density, and cardiovascular function make it a legitimate superfood, contributing to the healthy longevity observed in parts of Japan where it's a daily staple. While its distinctive flavor and texture may require adaptation, the health rewards are significant. It is, however, crucial to consider personal medical conditions, particularly when taking blood thinners, and to consult with a healthcare provider if needed. For most, a small, daily portion can be a simple, impactful way to boost overall wellness.

Learn more about fermented foods and their benefits here.

Frequently Asked Questions

Eating natto every day can significantly benefit your health by boosting gut flora with probiotics, improving cardiovascular health with nattokinase, and strengthening bones due to its rich vitamin K2 content. For most people, it can be a healthy daily addition, but it should be avoided by those with soy allergies.

Yes, for most people, it is safe to eat natto daily. However, individuals on blood-thinning medication like warfarin must be cautious and consult their doctor due to natto's high vitamin K2 content. Those with a soy allergy should also avoid it.

In Japan, natto is traditionally eaten for breakfast, often over rice, but it can be consumed at any time of day. Some evidence suggests eating it earlier in the day may support metabolism and morning energy, while nighttime consumption can aid skin repair.

Natto is exceptionally healthy due to its potent combination of nutrients. It is a rich source of plant-based protein, dietary fiber, probiotics (Bacillus subtilis), and especially vitamin K2, which is rare in other foods.

Natto is often described as having an umami, nutty, earthy, and sometimes bitter flavor. For many, the most notable aspect is its sticky, stringy, and slimy texture, which can be an acquired taste.

While generally safe, natto may cause minor side effects, especially if you're not used to eating fermented foods or high fiber. These can include temporary bloating or gas. Those with a soy allergy should not eat it.

To get past the texture, you can mix natto into other dishes, like scrambled eggs, soups, or rice bowls, where it is less noticeable. Powdered or freeze-dried natto options are also available, which offer the benefits without the strong texture and smell.