How Much Vitamin K2 Is in Natto? A Nutrition Guide

Reading time:14 min

Published:April 1, 2026

Author:

Cymbiotika

Finding nutrient-dense foods often feels like a puzzle. You likely know about the fiber in greens or the protein in beans. But when it comes to specific, harder-to-find nutrients like Vitamin K2, the search usually leads to one very unique food: natto. At Cymbiotika, we believe that understanding exactly what you put into your body is the first step toward a more intentional wellness routine.

Introduction

This guide will break down the exact Vitamin K2 content in natto, why this specific form of the vitamin is so important for your body, and how it compares to other food sources. We will also explore the science of absorption and why bioavailability is the most important factor to consider when adding any nutrient to your daily habits. By the end of this article, you will understand how to use natto—or its alternatives—to support your long-term health through food and options from the Healthy Aging & Recovery collection.

What Exactly Is Natto?

Natto is a traditional Japanese food made from fermented soybeans. It has a very distinct profile that can be surprising to those trying it for the first time. It is known for its powerful aroma, savory "umami" flavor, and a signature sticky, stringy texture. This texture is the result of the fermentation process, specifically the work of a beneficial bacterium called Bacillus subtilis natto.

To make natto, soybeans are soaked and steamed until they are soft. Then, they are inoculated with the bacteria and allowed to ferment at a specific temperature. During this time, the bacteria break down the proteins in the soy, making them easier to digest and creating a wealth of nutrients that aren't present in plain soybeans.

While the taste and texture are an acquired preference for some, natto is celebrated as a "superfood" because of its incredible nutrient density. It isn't just a source of protein; it is a living, probiotic food that provides enzymes and vitamins that are difficult to find in the modern Western diet. For more background on fermentation and Vitamin K2, explore how Vitamin K2 is made.

How Much Vitamin K2 Is in Natto?

When people ask about the K2 content of natto, they are usually looking for the "gold standard" of dietary sources. Natto is widely considered the most concentrated source of Vitamin K2 (specifically the MK-7 form) in the world.

The numbers can vary slightly depending on the fermentation time and the specific strain of bacteria used, but the averages remain consistently high. Generally, one tablespoon of natto contains about 150 micrograms (mcg) of Vitamin K2.

If you consume a standard serving, which is roughly 50 to 100 grams, the numbers become even more impressive:

Per 1 ounce (approx. 28g): About 250 to 300 mcg of Vitamin K2.
Per 100 grams (approx. 3.5oz): Between 850 and 1,000 mcg of Vitamin K2.

To put this into perspective, the suggested daily intake for general Vitamin K (which often focuses on K1) is usually between 90 and 120 mcg. Just one small spoonful of natto can provide more than the total daily requirement for Vitamin K.

Quick Answer: One tablespoon of natto typically provides about 150 mcg of Vitamin K2. A full 100-gram serving can provide up to 1,000 mcg, making it the highest dietary source of this nutrient available.

Understanding the Difference: K1 vs. K2

It is easy to get confused when looking at Vitamin K because it is actually a family of fat-soluble vitamins. The two most common forms are Vitamin K1 (phylloquinone) and Vitamin K2 (menaquinone). For a closer look at the differences between these forms, read this guide to Vitamin K2 and MK-7.

Vitamin K1 is primarily found in green leafy vegetables like spinach, kale, and broccoli. Its primary role in the body is related to healthy blood clotting. While K1 is essential, the body does not convert it to K2 very efficiently.

Vitamin K2 is found in fermented foods and animal products. Unlike K1, which mostly goes to the liver, K2 is distributed more widely to other tissues like your bones and the walls of your blood vessels. This is where the magic happens for long-term wellness. K2 is often further divided into subtypes, with MK-4 and MK-7 being the most studied. Natto is specifically rich in MK-7, which is known for staying in the bloodstream much longer than other forms.

Why Bioavailability Matters for Vitamin K2

You might see a high number on a nutrition label, but that doesn't always mean your body is using all of it. Bioavailability refers to how much of a nutrient actually reaches your bloodstream and becomes available for your body to use.

Standard supplements and even some foods can be difficult for the digestive system to process. Vitamin K2 is a fat-soluble vitamin. This means it requires healthy fats to be absorbed properly. If you eat natto—or take a K2 supplement—on an empty stomach without any fat, you may not be getting the full benefits. Learn more about why bioavailability matters for Vitamin K2 supplements.

In our formulations, we focus on delivery systems that bypass the traditional hurdles of digestion. For example, our Liposomal Vitamin D3 + K2 + CoQ10 is designed with a phospholipid bilayer. This is a tiny "bubble" made of the same material as your cell membranes. This delivery method helps the nutrients pass through the digestive tract and into the cells more effectively than standard capsules.

Key Takeaway: The form of Vitamin K2 in natto (MK-7) is highly bioavailable because it has a long half-life, meaning it stays active in your body for a longer duration compared to K1 or MK-4.

How Vitamin K2 Supports Your Body

The reason so many people are looking for ways to get more K2 into their routine is because of its unique role in managing calcium. Many people take calcium for their bones, but calcium needs a "GPS" to tell it where to go. This overview of Vitamin K2 benefits and basics provides additional context.

Bone Health

Vitamin K2 activates a protein called osteocalcin. This protein is responsible for taking calcium from your blood and binding it to the bone matrix. Without enough K2, calcium may stay in the bloodstream rather than strengthening your skeletal system. Many people find that supporting their K2 levels helps maintain bone density as they age.

Cardiovascular Support

One of the most important roles of K2 is keeping calcium out of places it shouldn't be. When calcium builds up in the arteries, it can lead to stiffening and other cardiovascular concerns. Vitamin K2 activates Matrix Gla Protein (MGP), which helps prevent calcium from depositing in the walls of your blood vessels.

The Synergy with Vitamin D3

Vitamin D3 and Vitamin K2 are often called a "dynamic duo." Vitamin D3 helps your body absorb calcium from the food you eat. Once that calcium is in your system, Vitamin K2 ensures it is directed to your bones and teeth. If you take high doses of Vitamin D3 without K2, you might end up with too much calcium circulating in your blood without a way to deposit it into your bones. You can also read about choosing the best form of Vitamin K2.

Comparing Natto to Other K2 Sources

If you aren't ready to add natto to your breakfast routine, you can find Vitamin K2 in other foods. However, the amounts are significantly lower. Most Western diets are naturally low in K2 because we have shifted away from traditional fermentation and grass-fed farming practices.

Food Source
Serving Size
Estimated Vitamin K2 (mcg)

Natto
1 tablespoon
150 mcg

Goose Liver
100 grams
369 mcg

Gouda Cheese
1 ounce
20 mcg

Egg Yolk
1 large
15 - 30 mcg

Grass-fed Butter
1 tablespoon
2 mcg

Sauerkraut
1/2 cup
2 - 5 mcg

Chicken Breast
100 grams
9 mcg

As you can see, you would have to eat a significant amount of cheese or eggs to equal the K2 found in just one small serving of natto.

Note: The K2 content in animal products depends heavily on what the animal ate. Grass-fed cows and pasture-raised chickens have much higher K2 levels because they consume Vitamin K1 from grass, which their bodies then convert into K2.

Why Is Vitamin K2 Deficiency Common?

Despite how important it is, many people in the US are deficient in Vitamin K2. There are a few reasons for this shift in our nutritional landscape:

Industrial Farming: Most livestock is now grain-fed rather than grass-fed. Without the K1 from fresh grass, these animals cannot produce Vitamin K2 in their fat and organs.
The "Low-Fat" Trend: Because K2 is fat-soluble and found in high-fat foods like egg yolks and whole-fat dairy, decades of low-fat diet trends led many people to avoid the very foods that contain it.
Lack of Fermented Foods: Traditional diets often included fermented vegetables and soy. In the modern diet, these have been replaced by processed foods that lack beneficial bacteria and the vitamins they produce.

If you don't consume natto and you don't eat a lot of organ meats or grass-fed dairy, you may want to look at how to supplement your intake to ensure your bones and heart have what they need.

Practical Ways to Eat Natto

If you want to try getting your K2 straight from the source, natto can be integrated into your diet in several ways. In Japan, it is a breakfast staple. Here are a few ways to make it more approachable:

Over Rice: This is the most common way to eat it. Serve a small portion of natto over warm white or brown rice.
The "Stir" Method: Before eating, stir the natto vigorously with chopsticks. This builds up the sticky strings, which are actually where much of the beneficial nattokinase enzyme is found.
Add Flavors: Most natto comes with small packets of hot mustard and a savory soy-based sauce. Adding these, along with some chopped green onions, can help balance the strong flavor.
Pair with Fat: Since K2 is fat-soluble, eating natto with a little avocado or a drizzle of sesame oil can help your body absorb the nutrients.

What to do next:

Start with a very small portion (one teaspoon) to see how you like the flavor.
Look for natto in the freezer or refrigerated section of your local Asian grocery store.
Check the label to ensure it is non-GMO and organic.

Supplementation: When Natto Isn't for You

Let's be honest—natto is not for everyone. The texture and smell can be a significant barrier. If you find that you cannot incorporate natto into your routine but still want to support your bone and heart health, supplementation is a practical alternative.

When choosing a supplement, the most important thing to look for is the form of K2. You want MK-7, which is the same form found in natto. It is more stable and stays in your system longer than MK-4.

At Cymbiotika, we prioritize delivery. Our Liposomal Vitamin D3 + K2 + CoQ10 provides a source of MK-7. By using liposomal delivery, we ensure the vitamin is wrapped in a protective layer that aids absorption. This is especially helpful for fat-soluble vitamins, which can sometimes be "washed out" of the system before they can be utilized.

Bottom line: If natto doesn't fit your palate, a liposomal MK-7 supplement can provide a consistent, bioavailable alternative to help fill the nutritional gap.

Managing Your Routine for Long-Term Health

Wellness isn't about one "miracle" food; it’s about the cumulative effect of your daily choices. Whether you choose to eat natto three times a week or take a daily supplement, consistency is what allows your body to maintain healthy levels of these essential nutrients.

If you are new to Vitamin K2, it is always a good idea to start slowly. Monitor how you feel and consider your overall diet. Are you getting enough healthy fats? Are you also supporting your Vitamin D levels? These nutrients work together, and a balanced approach is always more effective than focusing on one in isolation.

The Role of Nattokinase

One final benefit of natto that deserves a mention is an enzyme called nattokinase. This enzyme is produced during the fermentation process and is unique to natto. While Vitamin K2 is busy directing calcium, nattokinase is working to support healthy blood flow.

It helps the body break down fibrin, a protein involved in blood clotting. By supporting the body's natural ability to maintain smooth blood flow, nattokinase complements the cardiovascular benefits of Vitamin K2. This is another reason why natto is considered such a powerhouse for heart health.

Building a Strategy You Can Trust

We believe that your wellness journey should be built on a foundation of transparency and high-quality sourcing. Every ingredient matters. When we look at the traditional Japanese diet and the role of natto, we see a clear example of how food can act as a powerful tool for longevity. For more guidance on Vitamin K2 sources and formulation, explore this Vitamin K2 production and bioavailability guide.

If you aren't sure where to start with your own routine, our Health Quiz is designed to take the guesswork out of your wellness plan by providing recommendations based on your unique goals and lifestyle.

Building a routine you trust means choosing products and foods that are backed by science and formulated for maximum absorption. Whether that's through a traditional bowl of natto or an advanced liposomal formula, the goal is to empower your body to function at its best every single day.

FAQ

How much natto should I eat daily?

Most people find that a small serving of about one tablespoon to one ounce several times a week is enough to maintain healthy Vitamin K2 levels. Because natto is so concentrated, you do not need to eat large quantities to see the benefits.

Is all Vitamin K2 the same?

No, Vitamin K2 comes in several forms, the most common being MK-4 and MK-7. MK-4 is usually found in animal products and has a very short half-life, while MK-7 (found in natto) stays in your bloodstream for much longer, allowing your body more time to utilize it.

Can I get enough Vitamin K2 from a vegan diet without natto?

It is very difficult to get significant amounts of Vitamin K2 on a vegan diet without natto. While small amounts are found in other fermented foods like sauerkraut or kimchi, the levels are significantly lower, making natto or a high-quality vegan supplement the most reliable options.

Why is natto so sticky?

The stickiness is caused by a substance called polyglutamic acid, which is produced by the Bacillus subtilis bacteria during fermentation. These sticky strings are actually a sign of a healthy fermentation process and contain many of the food's beneficial enzymes.

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Table of Contents

Introduction

What Exactly Is Natto?

How Much Vitamin K2 Is in Natto?

Understanding the Difference: K1 vs. K2

Why Bioavailability Matters for Vitamin K2

How Vitamin K2 Supports Your Body

Comparing Natto to Other K2 Sources

Why Is Vitamin K2 Deficiency Common?

Practical Ways to Eat Natto

Supplementation: When Natto Isn't for You

Managing Your Routine for Long-Term Health

The Role of Nattokinase

Building a Strategy You Can Trust

FAQ

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What Exactly Is Natto?

How Much Vitamin K2 Is in Natto?

Understanding the Difference: K1 vs. K2

Why Bioavailability Matters for Vitamin K2

How Vitamin K2 Supports Your Body

Comparing Natto to Other K2 Sources

Why Is Vitamin K2 Deficiency Common?

Practical Ways to Eat Natto

Supplementation: When Natto Isn't for You

Managing Your Routine for Long-Term Health

The Role of Nattokinase

Building a Strategy You Can Trust

FAQ

Frequently searched

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Liposomal Advanced Creatine

Liquid Colostrum

Liposomal Elderberry