Is it safe to eat natto every day?: Examining the benefits and risks of daily consumption

October 6, 2025 •

4 min read

According to a 2020 announcement from Japan's National Cancer Center, high consumption of natto lowers mortality risk, drawing attention to this traditional fermented food worldwide. For centuries, the Japanese have enjoyed natto as a regular part of their diet, but many people outside of Japan question, 'Is it safe to eat natto every day?'. For most healthy individuals, the answer is yes, though certain health conditions warrant caution.

Quick Summary

Daily consumption of natto is generally safe and offers substantial health benefits, including enhanced heart and bone health and improved digestion. Key components like nattokinase and vitamin K2 are responsible for many positive effects. However, those on blood thinners, individuals with soy allergies, or people with thyroid issues should exercise caution and consult a healthcare provider.

Key Points

Generally Safe: For most healthy people, consuming natto daily in moderate portions is safe and associated with significant health benefits.
Blood Thinner Interaction: Individuals taking anticoagulant medications like warfarin must consult a doctor due to natto's high vitamin K2 content, which affects blood clotting.
Heart Health Boost: Natto contains nattokinase, an enzyme that supports healthy blood flow by helping to dissolve blood clots and potentially lowering blood pressure.
Bone Health Superfood: As a rich source of vitamin K2, natto helps direct calcium to the bones, contributing to stronger bone density and reduced fracture risk.
Gut Health Probiotics: The fermentation process provides beneficial Bacillus subtilis probiotics and fiber, which aid digestion and promote a healthy gut microbiome.
Allergy and Thyroid Watch: People with soy allergies should avoid natto, and those with impaired thyroid function should consult a doctor due to goitrogens.
Start Slowly: To acclimate to the flavor and high fiber, beginners should start with small daily portions and mix with other foods.

The Benefits of Eating Natto Daily

For most people, eating natto daily is not only safe but also offers a wide array of health advantages due to its dense nutritional profile. This traditional Japanese staple is packed with nutrients that become even more bioavailable through fermentation. Below are some of the most significant benefits of adding natto to your daily diet.

Heart Health and Blood Circulation

One of the most potent components of natto is nattokinase, an enzyme that forms during the fermentation process. Nattokinase is known for its ability to help dissolve blood clots, which aids in maintaining good blood vessel structure and improving blood flow. Studies have also linked nattokinase supplementation to reduced blood pressure. By supporting healthy circulation and potentially lowering blood pressure, daily natto intake contributes significantly to overall cardiovascular health.

Stronger Bones with Vitamin K2

Natto is an exceptional source of vitamin K2, a crucial nutrient often lacking in Western diets. Vitamin K2 plays a vital role in bone health by activating proteins that help build and maintain bone density. For populations like postmenopausal women at risk of osteoporosis, regular intake of vitamin K2 can be particularly beneficial. Some research indicates that daily natto consumption is linked to a lower risk of bone fractures.

Digestive Health and Probiotics

As a fermented food, natto is a natural source of beneficial probiotics, specifically the Bacillus subtilis natto bacteria used in its creation. Probiotics help maintain a healthy balance of gut flora, which can improve digestion and reduce symptoms like bloating and constipation. Furthermore, the fermentation process breaks down the antinutrients present in soybeans, making the vitamins and minerals easier for the body to absorb.

Rich in Essential Nutrients

Beyond its unique enzymes and probiotics, natto is a highly nutrient-dense food. A single serving provides substantial amounts of protein, fiber, manganese, and iron, along with smaller quantities of zinc, calcium, and B vitamins. This rich nutritional profile makes it a highly sustaining and beneficial addition to any daily diet.

Potential Risks and Precautions for Daily Natto

While largely safe, daily natto consumption is not recommended for everyone. Certain medical conditions or medications can interact negatively with its unique compounds, and portion control is always important.

Drug Interactions with Blood Thinners

The most significant risk associated with natto is its very high vitamin K2 content. Vitamin K plays an essential role in blood clotting, and its high concentration in natto can interfere with the effectiveness of anticoagulant medications like warfarin. If you are taking any blood-thinning medication, it is crucial to consult your doctor before adding natto or nattokinase supplements to your diet.

Soy Allergies and Intolerances

Natto is made from soybeans, so it is not suitable for individuals with a soy allergy. Although rare, some people may also experience digestive issues like bloating or gas due to the high fiber and probiotic content, especially when first introducing it to their diet.

Thyroid Function Concerns

As a soy product, natto contains goitrogens, compounds that can interfere with normal thyroid function. This is not typically an issue for healthy individuals, but those with pre-existing impaired thyroid function, such as hypothyroidism, may need to limit their intake and should consult a doctor.

Making Natto a Part of Your Daily Routine

For those cleared to consume it, here are some tips for incorporating natto into your daily meals:

Start small: If you're new to the texture and taste, begin with a small portion (e.g., 1 tablespoon) mixed with rice, which is how it's traditionally served in Japan.
Add condiments: Traditional Japanese condiments like soy sauce and karashi (Japanese mustard) can enhance the flavor and make it more palatable.
Mix well: Stirring natto vigorously with chopsticks helps develop its sticky, stringy texture and unlock more umami flavor.
Get creative: Incorporate natto into other dishes. You can add it to toast, pasta, scrambled eggs, or even as a topping for soup.
Monitor sodium intake: Be mindful of the sodium content if you regularly combine natto with soy sauce, miso, or other high-sodium ingredients.

Daily Natto: Benefits and Considerations Comparison Table


Aspect	Daily Natto Benefits	Daily Natto Considerations
Heart Health	Contains nattokinase, an enzyme that may help dissolve blood clots and lower blood pressure.	High vitamin K2 content can interfere with blood-thinning medications like warfarin.
Bone Health	Excellent source of vitamin K2, which aids in bone building and maintenance, potentially reducing fracture risk.	Excessive consumption is unlikely to be toxic but may require monitoring for those on specific medications.
Digestive System	Provides potent probiotics (Bacillus subtilis natto) and fiber, improving gut health and digestion.	May cause initial bloating or gas as the digestive system adjusts to the probiotic content.
Nutrient Absorption	Fermentation reduces antinutrients, enhancing the absorption of minerals like iron, manganese, and magnesium.	Requires portion control due to calorie density to avoid unintentional weight gain.
Overall Safety	Generally safe and associated with lower mortality risk in regular consumers.	Not suitable for individuals with soy allergies or those with pre-existing thyroid conditions.

Conclusion: Is Eating Natto Every Day Safe for You?

Eating natto every day is a safe and beneficial practice for most healthy individuals, aligning with a dietary pattern linked to longevity in Japan. Its significant benefits for heart, bone, and gut health are well-supported by its unique nutritional content, particularly nattokinase and vitamin K2. However, the key to safe daily consumption lies in personal health awareness. If you have a soy allergy, a thyroid condition, or are taking blood-thinning medications, you must consult with a healthcare professional before incorporating it into your routine. For those who can enjoy it, starting with a moderate daily portion is a powerful way to enhance your nutrient intake and overall well-being.

For more information on the health benefits of fermented foods, you can explore reputable health resources online, such as the articles referenced here, or consult with a registered dietitian.

Frequently Asked Questions

Yes, for the majority of healthy individuals, it is safe to eat natto every day. It is a daily staple in Japan, known for its numerous health benefits. However, people with specific health conditions should exercise caution.

Eating natto daily can improve heart health due to the enzyme nattokinase, strengthen bones with high vitamin K2 content, and support digestive health through probiotics.

Individuals on blood-thinning medications like warfarin, those with a soy allergy, or people with specific thyroid conditions should avoid or limit daily natto consumption after consulting a healthcare provider.

A typical daily portion of natto is about 1.5 ounces, or a standard 40-50 gram pack. A steady consumption of this amount is often sufficient for a healthy person.

Most people tolerate natto well, but some may experience gas or bloating initially due to the high fiber and probiotic content. These effects often subside as the digestive system adjusts.

Yes, the high concentration of vitamin K2 in natto can interfere with the effectiveness of anticoagulant drugs (blood thinners). It is critical to discuss daily natto intake with a doctor if you are on this type of medication.

To ease into the strong flavor and sticky texture, serve natto with rice and mix in condiments like soy sauce and mustard. Stirring it vigorously can also improve the texture and taste.