Why the Japanese Love NATTO and You Should Too

by John Moody | Affiliate linksComments: 22

natto benefits
The world of soy can be very confusing for consumers! Most soy based foods are downright dangerous especially for babies, children and those with thyroid disease. 

This would include modern concoctions such as soy formula, soya milk, bean curd or tofu along with the wide variety of processed foods containing this legume. It is a very important additive for the food industry because it is cheap to produce, replacing more expensive ingredients!

Dozens of scientific studies confirm the dangers of soy in the diet, although the soy industry has predictably countered with “science” of its own featuring cherry picked data and skewed statistics.

While most soy foods are deserving of a warning label, a few others are actually healthy such as traditional soy sauce, light or dark miso, tempeh and natto. These four lone exceptions have a long history of traditional use in various Asian diets. They also have good research supporting a positive role in human health.

Of these, the healthiest by far is natto. It is also the least popular, for reasons discussed further below.

What is Natto?

What do these few soy foods have in common? Generally speaking, it is fermentation. Soy is full of a host of anti-nutrients – phytates, goitrogens, phytoestrogens and more.

The truth is that ancient people groups didn’t consume much soy until they discovered the power of fermentation to unlock the nutritional potential by reducing the large amount of anti-nutrients that persist even after cooking for long periods of time.

This discovery occurred around a thousand years ago in China. Someone took some boiled soybeans and added an unknown colony of beneficial bacteria to it. About 24 hours later, natto was born!

Most likely, this happened by either accidental or purposeful contamination of the cooked soybeans with stray bacterial flora in the surrounding environment. A millennium ago, straw bags often served as the equivalent of lunch sacks in some places! This type of container would have contained probiotics that occur naturally on the surface of all living things.

A similar occurrence in the folklore apparently happened with the discovery of kefir. Shepherds in the Caucasus mountains observed that fresh milk carried in leather pouches would ferment into the tangy, effervescent beverage. Once again, the magical process took about 24 hours.

Why Fermented Soybeans are a Superfood

Today, natto is primarily enjoyed by the Japanese, who commonly enjoy a small dish of fermented soybeans with breakfast.

Modern science has shed light on natto’s nature and how it plays a powerful role in bolstering the health of this long lived culture. The bacteria Bacillus subtilis is responsible for turning the cooked soybeans into a superfood. This strain is also known by the common names hay bacillus or grass bacillus.

People have to lend a hand along the way, though. First, they must either boil or stream the beans. Then, they must inoculate them with the beneficial bacteria.

Last, the mixture needs time to ferment. Usually about 24 hours – a bit longer if temperatures are cool.

In the early 1900s, researchers figured out how to make the starter culture apart from using straw. This innovation allowed more consistent results in homemade natto production and the first large scale commercial production as well.

Natto is now enjoyed all over the world as a traditional food with a wide array of health benefits for those who consume it regularly.

Health Benefits of Natto

Natto is one of the few plant based food options that is truly nutrient dense. It is high in a number of minerals – manganese, iron, copper, potassium, phosphorus, and zinc. Since it is fermented, it is also an excellent source of vitamin K2, which few whole foods contain. Rampant K2 deficiency exists in the modern diet for this reason with deadly results.

In fact, natto is the highest food in Vitamin K2 on the planet! People who eat it regularly avoid the need for Vitamin K2 supplements.

How much does natto contain? Up to 100 times more K2 than many cheeses, which are the most accessible food in the Western diet that contains significant amounts of this nutrient. Gouda and brie are some of the highest.

Why is Vitamin K2 so Valuable?

Vitamin K2 is the kind of K our bodies desperately need. Similar to how our body needs true vitamin A, and not just beta carotene, K1 may get turned into K2 by our body.

Unfortunately, for genetic or other reasons such as gut imbalance, it frequently doesn’t happen that way. So, while plants are sometimes great sources of Vitamin K1 and many other precursors to nutrients our body needs, it doesn’t mean that we end up with the nutrients we need such as Vitamin K2.

Current estimates are that over 90% of people are deficient in Vitamin K2. Deficiency can manifest in a wide variety of ways such as excessive wrinkling of the skin, bone loss issues, cardiovascular disease, and cancer.

Since bacteria make K2 via fermentation, many fermented foods, especially natto, contain large amounts of it. Meat, dairy, eggs, and other animals foods contain varying amounts of K2. For those who eschew these foods or otherwise lack access to them, natto is one of the very few options to choose from to ensure sufficient K2 in their diet.

Even for those eating animal products, because few eat “nose to tail” organ meats, they may not get enough vitamin K2. So, natto can play a crucial role as a low cost, truly natural whole food that has many other benefits to boot.

How Much Natto to Eat and How Often?

Eating only a few ounces of natto equates to taking 5-6 (expensive) Vitamin K2 supplement capsules! A single 100 gram (3.5 ounce) serving contains 775 micrograms. Science shows that eating natto most definitely improves blood amounts of this crucial vitamin too. (1)

Thus, eating a serving of natto once or twice a week would provide plenty of K2 in the diet.

Natto Probiotics

Beyond its nutritional value, properly prepared natto is a powerful probiotic. Just be sure not to cook it else you destroy this major health benefit!

The final product is bursting with literally billions of beneficial bacteria. Studies have shown that the strains used to make natto may help with irritable bowel and ulcerative colitis among other health issues. (2, 3)

A number of studies show that natto, both its probiotic bacterial component and other compounds the final product contains, promote proper immune function and other immune system benefits. (4, 5)

Some doctors think that, unlike many other probiotics, natto may survive the body’s natural digestive defenses and help colonize our lower bowels with beneficial bacteria.


As a living food, natto brings one other benefit worth mentioning to the dinner table – enzymes. Health conscious people are familiar with the concept of popping digestive enzyme supplement after a meal of cooked or processed food to help nutrient assimilation and ward off unpleasant symptoms like bloating and heartburn. Why not just eat food that already contains them for a less expensive and more effective approach?

Natto contains one enzyme in particular, aptly named nattokinase, that shows numerous benefits for the cardiovascular system in particular. The enzymes found in natto also show possible health and other benefits beyond digestive according to Dr. Ralph Holsworth, an emergency room supervisor and biomedical researcher in a rural hospital in Colorado.

Dr. Holsworth has coauthored several studies on the enzyme nattokinase, a byproduct of natto fermentation. He says that this enzyme:

breaks down fibrin in the blood, a protein aggregate involved in blood clotting, decreases the ‘stickiness’ of the red blood cells, and assist in the prevention of arterial plaque formation.

These blood-thinning actions may lessen the severity of heart attacks and other cardiovascular events. (6)

Dr. Holsworth uses nattokinase in his own medical practice to help prevent blood clots and assist in healing from surgery. Nattokinase is not yet widely used in mainstream medical practice, although it has been gaining popularity as a food supplement with the public. (7)

So, with natto you get a food with an excellent nutrient profile plus many other known benefits. Yet, that doesn’t mean natto presents no dangers or problems.

Natto Dangers

While natto is a traditional food, modern soybeans are not your great, great grandma’s soybeans. In fact, soy is one of the worst of the worst of modern, industrialized crops. This means a high level of genetic modification such that you can literally douse the crops with Roundup without them dying!

Not just glyphosate containing herbicides either! Soy is endlessly sprayed with a myriad of other industrial agricultural chemicals. Just ask anyone who lives anywhere near a soybean farm!

After harvest, the soybeans are then processed with more toxic chemicals such as the known carcinogen hexane. (8)

Modern soy especially frankenfoods like seitan and soy protein isolate don’t come close to resembling their ancient roots. They don’t have the same health benefits by a long shot even when consuming it in whole form such as edamame.

Count on it having a great deal of chemical and pesticide residue contamination when it reaches store shelves.

Natto May Contribute to Allergies

One last note, natto (and soy sauce) is high in histamines. This is a chemical group common in fermented foods that are linked to things like allergies, acne and other skin related issues like eczema and rosacea.

They pop up whenever you have an immune response, helping eliminate the offending invader. Thus, histamines are both good and good for you. But some people overproduce histamines or suffer from histamine intolerance. This contributes to many issues like seasonal allergies and other autoimmunity problems.

If you are one of these people, you may still be able to eat natto and soy sauce. For some, you may just need to eat it infrequently or in very small amounts. Others may find they can’t tolerate it at all.

Organic Natto

With natto, it is very important to stick with an organic, traditionally made brand. Traditional natto is made only from soaked, then fermented whole soybeans.

Also note, most modern, mass produced natto is sold in styrofoam (polystyrene) packaging. This stuff is an environmental disaster and may put nasty stuff into the food it contains.

Look for organic natto in safer packaging options. Most good quality nattos will come in safer plastic or glass packaging. Asian grocery stores in the refrigerated or freezer section are a good place to look.

Taste and Texture Quite Unlike Any Other Food!

Like many fermented foods, natto is an acquired taste to put it mildly. Some people never get used to it, in fact! It has a very pungent aroma, along with a rather unappealing texture and taste.

These three strikes against it greatly impact what should be a highly nutritious food that most anyone can afford. Some people do seem to enjoy the taste, though, so don’t automatically assume you won’t like it. As one sampler put it, natto was at best, “Klingon food.” (9)

As the saying goes … don’t knock it until you try it!

Best Ways to Go Nutty with Natto

Since natto is a something that probably requires getting used to, if you want to try it, the safest and surest bet is to mix it with rice or soup. Don’t ever cook it though. Be sure to blend in once the mixing food has cooled a bit. Mixing in a dollop of cultured cream with a bowl soup at the table involves a similar process.

This recipe for natto fried rice is a good place to start.

Small amounts of natto (remember: you don’t need a lot to reap huge health benefits!) often does best when paired with a larger proportion of a relatively bland food. This effectively helps to disperse its strong smell and hide the unpleasant texture.

While mass produced natto is now easy to find, there are many local and regional options that are probably far better to support with your food dollars.

Start with a traditionally made, organic variety. Otherwise, you are likely getting GMO soy along with some glyphosate residue and possibly undesirable additives too.

Have you tried natto and lived to tale the tale? Do you eat it regularly and if so how so? What ways do you find to eat this traditional food that overcomes the strong smell and texture?

Posted under: Healthy Living, Sacred Foods

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