What Is Natto? The Fermented Soybean Superfood
This slimy, stinky soybean dish is virtually unknown in the U.S., but that's about to change. Is natto the next fountain of youth? Find out!
Quick Reference: What Is Natto?
- What it is: a traditional Japanese dish of whole soybeans fermented with Bacillus subtilis bacteria.
- Taste and texture: sticky, stringy, and pungent. Some say it smells like dirty socks. An acquired taste.
- How old: said to date back to the 10th century, and still a standard part of the Japanese breakfast.
- Why it matters: rich in protein, vitamins, minerals, and probiotics, with more vitamin K2 than any other known food.
- How to eat it: best cold or at room temperature with a dash of soy sauce over hot rice.
If you have ever wandered the breakfast table in Japan, you have likely met natto: a bowl of fermented soybeans, sticky and stringy, with an odor strong enough to clear a room. So what is natto, and why do so many people swear by it? It is a beloved Japanese dish that is virtually unknown in the United States, and while its slimy, gooey texture and pungent smell can be off-putting at first, the health benefits behind it are nothing short of remarkable. This 2026, more cooks on this side of the Pacific are giving it a try.
For centuries, Japanese women have been admired for their flawless, age-defying, supple skin, which many attribute to eating natto on a regular basis. Natto is said to have been around since the 10th century, and it remains a standard part of the Japanese breakfast, though people eat it at any hour of the day.
What Is Natto Made Of?
At its heart, natto is just soybeans and a helpful bacterium, but the dish carries a long history. It belongs to the same family of fermented soy foods as miso and tempeh, traditions that have fed households for generations. The flavor is earthy and savory, what cooks call umami, and the famous sticky strings come straight from the fermentation itself.
How Is Natto Made?
Making natto is a painstakingly long and involved process. Whole soybeans are soaked, then steamed or boiled. Bacillus subtilis bacteria is added, and the mixture is allowed to ferment over time. The result is a sticky, stringy concoction that is, by the cook’s own admission, “an acquired taste.” It is best served cold or at room temperature with a dash of soy sauce over hot rice. The fermentation is the same kind of old-world food science that turns cabbage into sauerkraut and milk into cheese.
Watch how it is made:
Natto: The Best Source of Vitamin K2
Natto is rich in protein, vitamins, minerals, and probiotics. It contains more vitamin K2 than any other known food on the planet. What is K2, you ask? Just like natto, very few people have heard of vitamin K2, yet it is vital to the health of our heart, bones, and general well-being. Like vitamins A, D, and E, vitamin K is an essential and naturally occurring fat-soluble vitamin. But unlike those other vitamins, it is not stored in the body, so it must be consumed daily through foods or supplements.
Vitamin K1, which assists in the process of blood clotting, comes from vegetable sources like asparagus, broccoli, Brussels sprouts, cabbage, spinach, and green leafy vegetables. Vitamin K2 is found in animal sources and fermented foods like natto. The Harvard T.H. Chan School of Public Health notes that natto is among the richest dietary sources of vitamin K2, and a peer-reviewed review in the National Library of Medicine archive lays out why vitamins K1 and K2 matter for human health. See why K2 is such an important vitamin:
Major Health Benefits of Vitamin K2
- Improves bone and dental health, as it assists in getting calcium where it is needed in the bones and teeth, forming, strengthening, and repairing them. It reduces the likelihood of bone loss, fractures, and osteoporosis in the bones. It also helps prevent tooth decay and plaque.
- Helps prevent and relieve varicose veins, as it prevents calcium build-up in the veins.
- Prevents kidney stones by stopping calcium from accumulating and forming stones in the kidneys.
- Protects the cardiovascular system and prevents hardening of the arteries.
- Reduces the risk and slows the progression of certain cancers.
- Reduces excessive menstrual bleeding.
- Prevents premature aging, as it helps maintain your skin’s natural elasticity. By preventing calcium from settling in elastin fibers, it keeps your skin supple, with no premature wrinkling.
- Promotes longevity.
- Natto keeps best fresh, so buy or make it on a day you will eat it.
- Our Best Days Calendar lists good days for canning, brewing, and other kitchen work, the same lunar timing folks have used for generations.
Other Ways to Get Vitamin K2
If you cannot get your hands on natto, or you do not have the patience to make your own batch (InstantPot owners can find recipes online), there are other ways to bring more vitamin K2 into your diet:
- Goose, beef, or chicken liver
- Grass-fed, raw hard cheeses such as Gouda, Gruyere, and Brie
- Free-range, organic eggs, particularly the yolks
- Grass-fed butter
- Grass-fed, organic beef
- Sauerkraut, kimchi, and other fermented vegetables
- Fermented cod liver oil
- Supplements (as with any supplement, consult with your physician before taking)
What Natto Tastes Like and How to Eat It
There is no use pretending: the first taste of natto surprises most newcomers. The smell is pungent, the texture is sticky and stringy, and the flavor is deeply savory. The traditional way to serve it is cold or at room temperature, spooned over hot rice with a dash of soy sauce. Many cooks stir it well first, which builds up those signature strings, then add chopped green onion, a little Japanese mustard, or a raw egg. If the smell is a hurdle, a splash of vinegar can cut it, the same trick folks reach for in plenty of old kitchen remedies. Start with a small spoonful and let your taste buds come around. If you would rather grow the soybeans yourself, our Gardening by the Moon Calendar shows the Best Days to plant them, region by region.
What Is Natto: Frequently Asked Questions
What is natto?
Natto is a traditional Japanese dish made from whole soybeans that are soaked, steamed or boiled, then fermented with Bacillus subtilis bacteria. The result is sticky, stringy, and pungent, with a strong odor some compare to dirty socks. It is said to date back to the 10th century and is a standard part of the Japanese breakfast.
Why is natto so healthy?
Natto is rich in protein, vitamins, minerals, and probiotics, and it contains more vitamin K2 than any other known food on the planet. Vitamin K2 supports the heart, bones, and general well-being by helping direct calcium where the body needs it.
What does natto taste like?
Natto has a deeply savory, earthy flavor with a sticky, stringy texture and a strong smell. It is widely called an acquired taste. The usual way to serve it is cold or at room temperature over hot rice with a dash of soy sauce, often with green onion or mustard stirred in.
What is the difference between vitamin K1 and vitamin K2?
Vitamin K1 assists in blood clotting and comes from vegetable sources like asparagus, broccoli, Brussels sprouts, cabbage, spinach, and green leafy vegetables. Vitamin K2 is found in animal sources and fermented foods such as natto, and it helps move calcium into the bones and teeth and away from the arteries.
How can I get vitamin K2 if I cannot find natto?
Other sources of vitamin K2 include goose, beef, or chicken liver, grass-fed raw hard cheeses like Gouda, Gruyere, and Brie, free-range egg yolks, grass-fed butter and beef, sauerkraut, kimchi and other fermented vegetables, and fermented cod liver oil. Supplements are an option too, but consult your physician before taking any.
Can you make natto at home?
Yes, though it is a painstakingly long and involved process. You soak whole soybeans, steam or boil them, add Bacillus subtilis bacteria, and let the mixture ferment over time. InstantPot owners can find recipes online. Have you ever tried, or will you consider trying, natto or adding vitamin K2 to your diet? Tell us your thoughts in the comments below.
Deborah Tukua
Deborah Tukua is a natural living, healthy lifestyle writer and author of 7 non-fiction books, including Pearls of Garden Wisdom: Time-Saving Tips and Techniques from a Country Home, Pearls of Country Wisdom: Hints from a Small Town on Keeping Garden and Home, and Naturally Sweet Blender Treats. Tukua has been a writer for the Farmers' Almanac since 2004.
- Deborah Tukua
- Deborah Tukua
- Deborah Tukua
- Deborah Tukua
When you say K2 are you talking about MK7 ?
I am new to K2 and have just found Natto. Have not tried it yet. However what is a starting dose of K2 and if I do not get it from Natto what would be the best other sources to get the same amount of K2?
I add it to oatmeal, with Wyman’s Frozen Blueberries, beet root powder, pomegtanate juice as my go to breakfast
I couldn’t pass the nasty slamming feeling of Natto. But I trick my mind by eating Banana at the same time. I added a little syrup to Natto and now I can eat Natto. My mind thinks that the slamming feeling comes from the banana…..it works!
Love it
Hi there, I started making Natto in my Instapot several weeks ago again after trying previously in my oven- much easier and tastes better. My husband and I are getting used to eating a couple tablespoons in the morning on rice with a little soy sauce, rice vinegar and mustard all which help the taste. It actually helps a lot with energy like a cup of coffee esp with my husband who has an auto immune issue. Also helps not to feel hungry. Hopefully will help immune system during this corona virus epidemic too.
Try adding some finely chopped green onions…
A Japanese woman I worked with introduced me to NATO and am hooked.
Haven’t had it in a while though
what is the price?
I’ll stick to my free range eggs every morning
What is the price of this natto? Also do you ship? I’m always interested in trying something new.
Hi Ricky Agnew: You can buy natto online (Amazon) or you can make your own. Google the recipes!