What is Natto Food and Why Should You Eat It?

Natto Food, a traditional Japanese dish of fermented soybeans, is celebrated for its unique flavor and exceptional nutritional profile. At foods.edu.vn, we’re here to guide you through everything you need to know about natto, from its health benefits and culinary uses to where to find it and even how to make your own. Discover how this superfood can enrich your diet with essential nutrients and delicious umami flavor. Dive into the world of fermented foods, probiotic benefits, and Japanese cuisine right here.

Table of Contents

What is Natto Food?
What are the Benefits of Natto Food?
How is Natto Food Made?
What Does Natto Food Taste Like?
How to Eat Natto Food: Serving Suggestions
Where to Buy Natto Food?
Is Natto Food Safe to Eat?
How to Store Natto Food?
What are the Nutritional Facts of Natto Food?
What are Some Delicious Recipes Using Natto Food?
Frequently Asked Questions (FAQs) about Natto Food

1. What is Natto Food?

Natto food is a traditional Japanese dish consisting of soybeans that have been fermented with Bacillus subtilis var. natto. This fermentation process gives natto its distinctive flavor, aroma, and sticky, stringy texture. Highly regarded in Japanese cuisine for centuries, natto is now gaining popularity worldwide due to its impressive health benefits and unique culinary applications. It’s a staple in many Japanese households, often eaten for breakfast, and it’s a versatile ingredient that can be incorporated into various dishes.

1.1. Historical and Cultural Significance of Natto

Natto’s history dates back to ancient Japan, with some theories suggesting its origin in the Nara period (710-794 AD). One popular legend tells the story of Minamoto no Yoshiie, a military commander, whose cooked soybeans were accidentally fermented when stored in rice straw bags. Upon discovering the changed soybeans, his soldiers found them palatable, leading to the adoption of natto as a food source.

Over the centuries, natto evolved from a rural food to a widely consumed dish across Japan. Different regions developed their own unique variations, leading to a diverse range of natto types, each with its own distinct flavor and texture. Today, natto remains an integral part of Japanese culinary heritage, enjoyed by people of all ages.

1.2. The Fermentation Process Explained

The fermentation process is key to natto’s unique properties. Here’s a simple breakdown:

Soaking and Cooking Soybeans: The process begins with soaking soybeans in water for an extended period, typically overnight, to rehydrate them. The soybeans are then steamed or boiled until they become tender.
Introducing Bacillus subtilis var. natto: Cooked soybeans are mixed with Bacillus subtilis var. natto, a bacterium specifically cultured for natto production. This bacterium is responsible for the fermentation.
Fermentation: The mixture is then kept at a consistent warm temperature, around 40°C (104°F), for approximately 24 hours. This controlled environment allows the bacteria to ferment the soybeans, breaking down their proteins and carbohydrates, which results in natto’s characteristic sticky texture and distinct aroma.
Aging: After fermentation, natto is typically aged in the refrigerator for a few days. This aging process further develops the flavor and enhances the stringiness.

This fermentation process not only transforms the soybeans’ texture and flavor but also significantly increases their nutritional value.

1.3. Different Types of Natto

Natto comes in various forms, each offering a unique experience:

Daikoku Natto: This is the most common type, made with regular-sized soybeans. It has a strong flavor and a pronounced stringy texture.
Kotsubu Natto: Made with smaller soybeans, kotsubu natto has a milder flavor and a softer texture, making it a great option for those new to natto.
Hikiwari Natto: This type is made from chopped soybeans, resulting in a finer texture and a quicker fermentation process. It is often preferred by those who find the whole bean texture off-putting.
Shiokara Natto: A saltier, more pungent version of natto that is often aged for a longer period.
Godzilla Natto: Large natto beans that are known for being extra stinky.

Each type offers a different culinary experience, catering to diverse preferences.

2. What are the Benefits of Natto Food?

Natto is not just a unique food; it’s a nutritional powerhouse. Here are some compelling reasons to include natto in your diet:

2.1. Rich in Vitamin K2

Natto is one of the richest known sources of vitamin K2 (menaquinone-7 or MK-7), a nutrient crucial for bone health and cardiovascular function. Vitamin K2 helps direct calcium to the bones and teeth, preventing it from depositing in the arteries, thus reducing the risk of arterial calcification. According to a study published in the “American Journal of Clinical Nutrition,” vitamin K2 plays a vital role in maintaining bone density and reducing the risk of fractures, particularly in postmenopausal women. This makes natto an excellent dietary choice for those looking to support bone health and prevent osteoporosis.

2.2. High in Protein

Natto is an excellent source of plant-based protein, containing all nine essential amino acids. Protein is vital for building and repairing tissues, supporting immune function, and producing enzymes and hormones. For vegetarians and vegans, natto offers a convenient and complete protein source, contributing to overall health and well-being.

2.3. Probiotic Powerhouse

The fermentation process endows natto with a wealth of probiotics, beneficial bacteria that promote gut health. These probiotics can improve digestion, enhance nutrient absorption, and strengthen the immune system. A healthy gut microbiome is linked to numerous health benefits, including reduced inflammation and improved mental health.

2.4. Source of Nattokinase

Natto contains nattokinase, an enzyme produced during the fermentation process. Nattokinase is known for its potential cardiovascular benefits, including its ability to help dissolve blood clots and improve blood flow. Some studies suggest that nattokinase may help reduce blood pressure and lower the risk of heart disease, making natto a heart-healthy addition to your diet.

2.5. Packed with Essential Nutrients

In addition to vitamin K2, protein, and probiotics, natto is rich in other essential nutrients, including iron, calcium, magnesium, potassium, and dietary fiber. These nutrients play critical roles in various bodily functions, contributing to overall health and vitality.

2.6. Potential Benefits for Heart Health

Nattokinase, a key component of natto, has been shown in studies to have potential benefits for heart health. According to research published in the journal “Nutrition,” nattokinase can help lower blood pressure, reduce LDL cholesterol levels, and prevent atherosclerosis, thus reducing the risk of heart disease. Incorporating natto into your diet may be a proactive step toward maintaining a healthy cardiovascular system.

2.7. Promotes Bone Health

The high vitamin K2 content in natto is crucial for bone health. Vitamin K2 helps activate osteocalcin, a protein that binds calcium to bones, increasing bone density and strength. Regular consumption of natto may help prevent osteoporosis and reduce the risk of fractures, particularly in older adults.

2.8. Supports Digestive Health

The probiotics in natto promote a healthy gut microbiome, which is essential for digestive health. These beneficial bacteria can help improve digestion, reduce bloating, and enhance nutrient absorption. A balanced gut microbiome is also linked to improved immune function and overall well-being.

2.9. May Improve Cognitive Function

Some studies suggest that the nutrients in natto, including vitamin K2 and probiotics, may have cognitive benefits. Vitamin K2 has been shown to protect against age-related cognitive decline, while probiotics can improve brain function by promoting a healthy gut-brain axis. Incorporating natto into your diet may help support cognitive health and improve overall brain function.

2.10. Excellent for Plant-Based Diets

For those following a plant-based diet, natto is an invaluable source of nutrients that can be challenging to obtain from other plant-based foods. It provides a complete protein source, vitamin K2, iron, and probiotics, making it an excellent addition to vegetarian and vegan diets.

2.11. May Reduce Cancer Risk

Some research suggests that natto may have anti-cancer properties. A study published in the “European Journal of Cancer Prevention” found that regular consumption of natto was associated with a reduced risk of certain types of cancer, including breast and prostate cancer. The bioactive compounds in natto, such as isoflavones and nattokinase, may play a role in inhibiting cancer cell growth and preventing metastasis.

2.12. Anti-Inflammatory Properties

Natto contains compounds with anti-inflammatory properties, which can help reduce chronic inflammation in the body. Chronic inflammation is linked to various health problems, including heart disease, diabetes, and arthritis. By incorporating natto into your diet, you may help lower inflammation levels and reduce your risk of these chronic diseases.

2.13. Supports Immune Function

The probiotics in natto play a crucial role in supporting immune function. These beneficial bacteria help strengthen the gut barrier, preventing harmful pathogens from entering the bloodstream. They also stimulate the production of immune cells, enhancing the body’s ability to fight off infections and diseases.

2.14. May Help Regulate Blood Sugar Levels

Some studies suggest that natto may help regulate blood sugar levels, making it a beneficial food for individuals with diabetes or insulin resistance. The dietary fiber and probiotics in natto can slow down the absorption of glucose, preventing spikes in blood sugar levels after meals. Incorporating natto into your diet may help improve glycemic control and reduce the risk of diabetes-related complications.

2.15. Promotes Longevity

The combination of nutrients and bioactive compounds in natto makes it a potential food for promoting longevity. By supporting heart health, bone health, digestive health, and immune function, natto can help reduce the risk of chronic diseases and improve overall quality of life, potentially extending lifespan.

Benefit	Description	Source
Rich in Vitamin K2	Crucial for bone and cardiovascular health; directs calcium to bones and prevents arterial calcification.	“American Journal of Clinical Nutrition”
High in Protein	Provides all nine essential amino acids, vital for building and repairing tissues, supporting immune function, and producing enzymes and hormones.	USDA FoodData Central
Probiotic Powerhouse	Enhances gut health, improves digestion, strengthens the immune system, and reduces inflammation.	“Journal of Applied Microbiology”
Source of Nattokinase	Dissolves blood clots, improves blood flow, reduces blood pressure, and lowers the risk of heart disease.	“Nutrition”
Packed with Nutrients	Rich in iron, calcium, magnesium, potassium, and dietary fiber, contributing to overall health and vitality.	USDA FoodData Central
Heart Health	Nattokinase can lower blood pressure, reduce LDL cholesterol, and prevent atherosclerosis.	“Nutrition”
Bone Health	Vitamin K2 activates osteocalcin, increasing bone density and strength, preventing osteoporosis and reducing the risk of fractures.	“American Journal of Clinical Nutrition”
Digestive Health	Probiotics balance the gut microbiome, improving digestion, reducing bloating, and enhancing nutrient absorption.	“Journal of Applied Microbiology”
Cognitive Function	Vitamin K2 and probiotics may protect against age-related cognitive decline and improve brain function.	“Frontiers in Aging Neuroscience”
Plant-Based Diets	Excellent source of protein, vitamin K2, iron, and probiotics, invaluable for vegetarians and vegans.	USDA FoodData Central
Reduced Cancer Risk	Regular consumption associated with reduced risk of certain cancers due to bioactive compounds like isoflavones and nattokinase.	“European Journal of Cancer Prevention”
Anti-Inflammatory	Contains compounds with anti-inflammatory properties, reducing chronic inflammation.	“Journal of Nutritional Biochemistry”
Immune Function	Probiotics strengthen the gut barrier, stimulate immune cells, and enhance the body’s ability to fight off infections.	“Gut Microbes”
Blood Sugar Regulation	Dietary fiber and probiotics slow glucose absorption, preventing blood sugar spikes, and improving glycemic control.	“Diabetes Care”
Promotes Longevity	Supports heart, bone, digestive, and immune health, reducing the risk of chronic diseases and improving overall quality of life.	Multiple sources across nutritional and medical journals

3. How is Natto Food Made?

Making natto at home is a rewarding experience that allows you to control the quality and ingredients. Here’s a detailed guide on how to make your own natto:

3.1. Ingredients You’ll Need

1 cup of dried soybeans
Water for soaking and cooking
Natto starter culture (Bacillus subtilis var. natto) or store-bought natto

3.2. Equipment

Large bowl
Large pot or pressure cooker
Steamer basket (optional)
Sterilized container(s) with lids
Thermometer
Incubator or a warm, draft-free place

3.3. Step-by-Step Instructions

Soaking the Soybeans:
- Rinse 1 cup of dried soybeans thoroughly.
- Place the soybeans in a large bowl and cover with plenty of water. Soybeans will expand significantly, so ensure there’s enough water.
- Soak the soybeans for 12-24 hours at room temperature. Change the water every 6-8 hours to prevent fermentation or spoilage during the soaking process.
Cooking the Soybeans:
- After soaking, drain and rinse the soybeans.
- Boiling Method: Place the soybeans in a large pot and cover with fresh water. Bring to a boil, then reduce heat and simmer for 3-4 hours, or until the soybeans are very tender. You should be able to easily mash them with your fingers. Add more water as needed to keep the soybeans submerged.
- Steaming Method: Place the soybeans in a steamer basket over a pot of boiling water. Steam for 4-5 hours, or until the soybeans are very tender. Check water levels periodically to ensure the pot doesn’t run dry.
- Pressure Cooking Method: Place the soybeans in a pressure cooker with enough water to cover them. Cook at high pressure for 20-25 minutes, followed by a natural pressure release.
Sterilizing the Equipment:
- While the soybeans are cooking, sterilize the containers and lids you’ll use for fermentation. This can be done by boiling them in water for 10 minutes or running them through a dishwasher cycle with a sterilization setting.
- Ensure all other utensils that will come into contact with the soybeans are also sterilized.
Preparing the Natto Starter:
- If using a natto starter culture, follow the instructions on the package to activate it. Typically, this involves dissolving the starter in a small amount of sterilized water.
- If using store-bought natto, mix 1-2 tablespoons of natto with a small amount of sterilized water.
Inoculating the Soybeans:
- Once the soybeans are cooked and still warm (around 130-140°F or 55-60°C), drain them well.
- Transfer the warm soybeans to a sterilized container.
- Pour the natto starter culture or the mixture of store-bought natto over the soybeans.
- Mix thoroughly but gently to ensure the starter is evenly distributed throughout the soybeans.
Fermenting the Natto:
- Cover the container with a lid, leaving a small gap for air circulation. You can also use a sterilized cloth or paper towel secured with a rubber band.
- Place the container in an incubator or a warm, draft-free place. The ideal temperature for fermentation is around 104°F (40°C).
- Maintain this temperature consistently for 20-24 hours. You can use a yogurt maker, a heating pad, or an oven with a proofing setting to maintain the temperature.
Checking for Fermentation:
- After 20-24 hours, check the natto for signs of fermentation. The soybeans should be covered with a white film, have a strong, distinct aroma, and be sticky and stringy when stirred.
- If the natto doesn’t have these characteristics, continue fermenting for another 4-6 hours, checking periodically.
Aging the Natto:
- Once the natto has fermented properly, remove it from the incubator.
- Cover the container tightly with a lid and refrigerate for at least 24 hours to allow the flavor to develop fully.
Serving and Enjoying:
- After aging, your homemade natto is ready to eat.
- Serve it chilled or at room temperature, typically with soy sauce, mustard, and chopped green onions.

3.4. Tips for Success

Sterilization is Key: Proper sterilization of equipment is essential to prevent unwanted bacteria from interfering with the fermentation process.
Temperature Control: Maintaining a consistent temperature is crucial for successful fermentation. Use a reliable thermometer to monitor the temperature.
Quality Starter: Using a high-quality natto starter culture or fresh store-bought natto will ensure the best results.
Patience: Fermentation takes time, so be patient and allow the natto to ferment fully.
Experiment: Once you’re comfortable with the basic process, experiment with different types of soybeans and fermentation times to find your preferred flavor and texture.

By following these steps, you can easily make your own delicious and nutritious natto at home.

4. What Does Natto Food Taste Like?

Natto has a very distinct flavor profile that many find unique. Describing the taste of natto is challenging because it’s unlike anything else. Most people describe it as having a combination of the following:

Earthy: Similar to the flavor of soil or mushrooms.
Nutty: A slight resemblance to nuts.
Umami: A savory, brothy taste.
Salty: A mild saltiness.

4.1. The Aroma of Natto

Beyond the flavor, natto also has a strong and distinct aroma. Many people find the smell to be pungent and similar to aged cheese or strong ammonia. This aroma is a result of the fermentation process and the compounds produced by Bacillus subtilis var. natto.

4.2. The Texture of Natto

The texture of natto is one of its most defining characteristics. It is sticky, slimy, and stringy, which can be off-putting to some people. The stringiness is due to the formation of long chains of polyglutamic acid during fermentation. When stirred, natto becomes even more stringy, creating a web-like appearance.

4.3. How Taste Varies

The taste of natto can vary depending on several factors, including the type of soybeans used, the fermentation time, and the specific strain of Bacillus subtilis var. natto. Some natto may have a stronger flavor and aroma, while others may be milder and more palatable.

4.4. Acquiring a Taste for Natto

For many people, the taste and texture of natto can take some getting used to. It’s not uncommon to find it unappetizing at first. However, with repeated exposure, many people develop a liking for natto and even come to crave it. The key is to start with small portions and try different ways of preparing and seasoning it.

4.5. Taste Enhancers

To make natto more palatable, it is often served with various condiments and seasonings. Common additions include:

Soy Sauce: Adds saltiness and umami.
Mustard: Provides a sharp, spicy kick.
Green Onions: Offer a fresh, mild onion flavor.
Tare Sauce: A specially flavored sauce that often comes with packaged natto.
Bonito Flakes: Add a smoky, savory flavor.
Kimchi: Provides a spicy, fermented flavor.

These additions can help balance the flavor of natto and make it more enjoyable.

4.6. Culinary Combinations

Natto can also be incorporated into various dishes to enhance their flavor and nutritional value. It pairs well with:

Rice: A classic combination, often eaten for breakfast.
Noodles: Added to soba or udon for extra flavor and texture.
Eggs: Mixed into omelets or scrambled eggs.
Salads: Provides a unique twist to salads.
Sushi: Used as a filling in maki rolls.

By experimenting with different combinations, you can find ways to enjoy natto that suit your taste preferences.

5. How to Eat Natto Food: Serving Suggestions

Natto is a versatile food that can be enjoyed in many ways. Here are some popular serving suggestions:

5.1. Traditional Japanese Style

The most common way to eat natto in Japan is with rice. Here’s how:

Prepare Rice: Cook a bowl of fresh, steamed rice.
Stir Natto: Open the natto package and remove any sauce or mustard packets. Stir the natto vigorously with chopsticks until it becomes very stringy and frothy. This process enhances the flavor and texture.
Add Seasonings: Add the included sauce and mustard, or use soy sauce and Japanese mustard (karashi).
Pour Over Rice: Pour the natto over the hot rice.
Mix and Enjoy: Mix the natto thoroughly with the rice and enjoy.

This simple yet satisfying combination is a staple in many Japanese households.

5.2. Natto with Toppings

To enhance the flavor and texture of natto, try adding various toppings:

Green Onions: Chopped green onions add a fresh, mild onion flavor.
Bonito Flakes: These dried, shaved fish flakes provide a smoky, umami flavor.
Raw Egg Yolk: A raw egg yolk adds richness and creaminess.
Seaweed: Nori or other types of seaweed provide a salty, marine flavor.
Kimchi: Fermented kimchi adds a spicy, tangy kick.
Avocado: Diced avocado adds creaminess and healthy fats.

Experiment with different toppings to find your favorite combination.

5.3. Natto in Maki Rolls

Natto can be used as a filling in maki rolls, adding a unique flavor and texture. Here’s how:

Prepare Sushi Rice: Cook and season sushi rice according to your preference.
Assemble Maki Rolls: Place a sheet of nori seaweed on a bamboo sushi rolling mat. Spread a thin layer of sushi rice over the nori, leaving a small strip uncovered at the top edge.
Add Natto: Place a line of natto along the center of the rice.
Roll the Maki: Using the bamboo mat, roll the maki tightly.
Slice and Serve: Slice the maki into bite-sized pieces and serve with soy sauce and wasabi.

5.4. Natto on Toast

For a quick and easy breakfast or snack, try natto on toast:

Toast Bread: Toast a slice of your favorite bread.
Spread Natto: Spread a layer of natto over the toast.
Add Toppings: Add toppings such as avocado, green onions, or a fried egg.

This combination provides a satisfying mix of textures and flavors.

5.5. Natto in Soups and Noodles

Natto can be added to soups and noodle dishes for extra flavor and nutrition:

Miso Soup: Add a spoonful of natto to miso soup for a boost of probiotics and umami.
Udon or Soba: Mix natto with udon or soba noodles, along with soy sauce, green onions, and other toppings.

5.6. Natto in Omelets and Eggs

Adding natto to omelets or scrambled eggs is a great way to incorporate it into your diet:

Prepare Eggs: Whisk eggs with a little milk or water.
Add Natto: Mix in a spoonful of natto.
Cook Omelet or Scramble: Cook the omelet or scrambled eggs as usual.
Add Toppings: Top with green onions, soy sauce, or other desired toppings.

5.7. Natto in Salads

Natto can add a unique twist to salads:

Prepare Salad: Prepare your favorite salad with greens, vegetables, and dressing.
Add Natto: Sprinkle natto over the salad.
Toss and Serve: Toss the salad gently and serve immediately.

5.8. Natto as a Condiment

Natto can be used as a condiment to add flavor and nutrition to various dishes:

Vegetable Dishes: Top steamed or roasted vegetables with natto.
Grain Bowls: Add natto to grain bowls for extra protein and probiotics.
Snacks: Enjoy natto with crackers or rice cakes.

By experimenting with these serving suggestions, you can find creative and delicious ways to enjoy natto.

Serving Suggestion	Description	Recommended Toppings/Additions
Traditional Japanese Style	Served with rice, a staple in many Japanese households.	Soy sauce, Japanese mustard (karashi), green onions
Natto with Toppings	Enhanced with various toppings to add flavor and texture.	Green onions, bonito flakes, raw egg yolk, seaweed, kimchi, avocado
Natto in Maki Rolls	Used as a filling in maki rolls for a unique flavor and texture.	Sushi rice, nori seaweed, soy sauce, wasabi
Natto on Toast	Quick and easy breakfast or snack option.	Avocado, green onions, fried egg
Natto in Soups and Noodles	Added to soups and noodle dishes for extra flavor and nutrition.	Miso soup, udon, soba, green onions
Natto in Omelets and Eggs	Incorporated into omelets or scrambled eggs for a protein and probiotic boost.	Green onions, soy sauce
Natto in Salads	Adds a unique twist to salads with greens, vegetables, and dressing.	Your favorite salad ingredients and dressing
Natto as a Condiment	Used as a condiment to add flavor and nutrition to various dishes.	Steamed or roasted vegetables, grain bowls, crackers, rice cakes

6. Where to Buy Natto Food?

Finding natto can be easier than you think. Here are several places where you can purchase natto:

6.1. Asian Supermarkets

Asian supermarkets are the most reliable place to find natto. These stores typically carry a variety of natto brands and types, including daikoku natto, kotsubu natto, and hikiwari natto. Some popular Asian supermarket chains that carry natto include:

Mitsui Foods: Offers a wide selection of Japanese and Asian products.
H Mart: A large Korean supermarket chain with a good selection of Japanese ingredients.
T&T Supermarket: A Canadian-based Asian supermarket chain with locations in the United States.
Weee!: America’s largest online Asian grocery store carries a variety of natto products.

Check the refrigerated section of these stores, typically near the tofu and other fermented products.

6.2. Online Retailers

Many online retailers offer natto for sale, making it convenient to purchase from the comfort of your home:

Amazon: Offers a variety of natto brands and types, often with subscription options for regular delivery.
Weee!: As mentioned earlier, Weee! has an extensive selection of natto and delivers across the US.
Specialty Online Stores: Some online stores specialize in Japanese or fermented foods and offer a curated selection of natto.

When purchasing natto online, be sure to check the shipping and storage information to ensure the product arrives in good condition.

6.3. Health Food Stores

Some health food stores may carry natto, particularly those that focus on international or fermented foods. Check the refrigerated section or ask a store employee for assistance.

6.4. Japanese Restaurants

Some Japanese restaurants may sell natto to take home. If you enjoy natto at a local Japanese restaurant, ask if they sell it retail.

6.5. Local Farms and Producers

In some areas, local farms or producers may make and sell natto. Check your local farmers’ markets or search online for local natto producers.

6.6. Tips for Buying Natto

Check the Expiration Date: Make sure to check the expiration date before purchasing natto to ensure it is fresh.
Read the Label: Read the label to check the ingredients and nutritional information.
Consider the Type: Choose the type of natto that suits your taste preferences. If you are new to natto, consider starting with kotsubu natto, which has a milder flavor and softer texture.
Storage: Natto should be stored in the refrigerator. If purchasing online, make sure the seller provides proper packaging and shipping to maintain its quality.

Retailer	Type of Store	Brands/Types Available	Notes
Asian Supermarkets	Physical Store	Daikoku Natto, Kotsubu Natto, Hikiwari Natto, various regional brands	Most reliable source; check refrigerated section near tofu and fermented products.
Mitsui Foods	Physical Store	Wide selection of Japanese and Asian products	Look for refrigerated section.
H Mart	Physical Store	Korean supermarket with a good selection of Japanese ingredients	Check the refrigerated section.
T&T Supermarket	Physical Store	Canadian-based Asian supermarket with locations in the United States	Check the refrigerated section.
Online Retailers	Online Store	Various brands and types, often with subscription options	Check shipping and storage information to ensure product arrives in good condition.
Amazon	Online Store	Variety of brands and types	Check expiration date and seller ratings.
Weee!	Online Store	Extensive selection of natto and delivers across the US	Good for those without local Asian markets.
Specialty Online Stores	Online Store	Curated selection of Japanese or fermented foods	May offer unique or artisanal natto.
Health Food Stores	Physical Store	Limited selection; may focus on international or fermented foods	Check refrigerated section and inquire with store employees.
Japanese Restaurants	Restaurant	May sell natto to take home	Ask if they sell retail.
Local Farms/Producers	Farmers’ Markets, Online	Locally made natto; may offer unique flavors or ingredients	Check local listings or search online for producers in your area.

7. Is Natto Food Safe to Eat?

Natto is generally safe for most people to eat. However, there are some considerations to keep in mind:

7.1. Vitamin K Content

Natto is very high in vitamin K2, which can interfere with blood-thinning medications such as warfarin. If you are taking blood thinners, consult with your doctor before adding natto to your diet. They may need to adjust your medication dosage to account for the increased vitamin K intake.

7.2. Soy Allergies

Natto is made from soybeans, so people with soy allergies should avoid it. Allergic reactions to soy can range from mild symptoms such as hives and itching to severe symptoms such as anaphylaxis. If you have a soy allergy, carefully read the labels of all food products and avoid those that contain natto.

7.3. Purine Content

Soybeans are relatively high in purines, which can be a concern for people with gout. Purines are broken down into uric acid, and high levels of uric acid can lead to gout flare-ups. If you have gout, consume natto in moderation and consult with your doctor or a registered dietitian for personalized dietary advice.

7.4. Histamine Intolerance

Fermented foods like natto can be high in histamine, which can trigger symptoms in people with histamine intolerance. Symptoms of histamine intolerance can include headaches, skin rashes, digestive issues, and nasal congestion. If you have histamine intolerance, start with small portions of natto and monitor your symptoms.

7.5. Bacterial Contamination

While natto is made through a controlled fermentation process, there is always a risk of bacterial contamination if the process is not done correctly. To minimize this