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Natto Health Benefits: 9 Reasons Why You Should Eat It

What is Natto

It’s a fermented soybean originating from Northeastern Japan. The bacteria Bacillus subtilis ferments the pre-cooked soybeans into natto in approximately 24 hours.

The fermentation process changes the chemical structure of the soybeans and produces probiotics and other healthy nutrients. Natto contains nattokinase and is considered one of the healthiest superfoods available for human consumption.

Natto is regarded as a fibrinolytic miracle food because it improves blood circulation and helps decrease the risk of a variety of cardiovascular diseases.

Is Natto keto-friendly?

Yes, the fermentation of the natto reduces the sugar content of the soybeans by approximately 15%. One-quarter cup of natto contains only 4 net carbohydrates. It’s also very low on the glycemic index and high in soluble fibers, which means it won’t spike blood sugar.

How much vitamin K2 is in Natto?

100 grams of Natto contains about 939 mcg grams of vitamin K2. You would have to eat approximately 14 egg yokes to match the K2 content of Natto.

What does Natto taste like?

Natto has a unique taste and can’t really be compared to anything. I will say it’s strong, pungent and earthy, like nutritional yeast. Natto has a slimy mouthfeel and smells a little like fermenting beer or dirty socks.

What is Natto’s benefits for weight loss?

Natto raises blood sugar only slightly because the fiber slows the absorption of the sugars. Also the fiber, fat, and protein helps curb your appetite and improve satiety. Soy fiber also provides important health benefits including improved bowel movements and the ability to lower cholesterol.

keto friendly Natto

It’s also called itohiki natto, or “stringy natto”

They also eat fermented soybeans in the Himalayan regions of Nepal, India, and Bhutan, but call it Kinema instead of Natto.

The history of Natto

The story goes like this: Around 1086 AD the Japanese Samurai clan Minamoto no Yoshiie were attacked while boiling soybeans for their horses. They quickly packed up the beans in straw bags and threw them on their horses.

A few days later the body heat from the horses and the bacillus bacteria from the straw bags fermented the soybeans into Natto. The Samurai warriors were famished and ate the fermented soybeans, and liked them.

Natto Health Benefits

The health benefits of Natto are pretty amazing. Nutritional nattokinase is emerging science and I am starting to actually see nattokinase supplements sold in the health food stores.

Nattokinase is a health benefit of Natto
Nattokinase Supplements

Nattokinase and K2 nutritional supplements are not cheap, approximately $60 for a 30 day supply (combined). Natto is very nutrient-dense. You could get (approximately) the same amount on K2 and nattokinase in 1 pound of dry soybeans fermented into Natto.

Health Benefits of Nattokinase
Source: National Institute of Health

Eating complex carbohydrates like Natto and lowering simple sugar consumption is the key to preventing and even reversing type 2 diabetes.

Natto also contains lecithin

Yet another health benefit of Natto is lecithin. It (lecithin) is a phospholipid containing unsaturated fatty acids. Lecithin has been shown to reduce coronary artery diseases by preventing cholesterol deposits on the vascular endothelium and to prevent liver damage.

Natto is so rich and pungent you probably couldn’t eat more than a 1/4 cup at one time even if you wanted to.  

The nutritional content of 1/4 cup of Natto:

  • Total Fat 4.81 g
  • Saturated Fat 0.70 g
  • Polyunsaturated Fat 2.72 g
  • Monounsaturated Fat 1.06 g
  • Cholesterol 0
  • Sodium 3 mg
  • Total Carbohydrate 6.3 g
  • Dietary Fiber 2.4 g
  • Sugars 1.6 g
  • Protein 7.8 g

Natto also contains isoflavones, lethicin, linoleic acid, enzymes, bioactive peptides, probiotics, prebiotic fiber, nattokinase, and gamma-polyglutamic acid.

Natto’s health benefits are eye-watering, it has more vitamin K2 than any other food on earth. This study on Pubmed titled, “Intake of fermented soybean (natto) increases circulating vitamin K2 (menaquinone-7)” suggests that intake of fermented soybeans (natto) increases serum levels of MK-7 significantly.

natto-high-amount-Vitamin K2
Vitamin K2 in the form of MK7 is found in Natto

The MK-7 version of K2 is superior and Vitamin K2 contributes to bone health, prevents cardiovascular disease and could potentially prevent Alzheimer’s disease.

Natto also contains large amounts of Nattokinase

You won’t see Nattokinase advertised on TV because the drug companies can’t patent it and make a profit with it. But, make no mistake, Natto, because of nattokinase, is arguably the most healthy super-food in existence today.

Nattokinase (NK) is an ultra-powerful blood-clot dissolving protein used for the treatment of cardiovascular diseases. This website: is devoted to nattokinase and is very informative.

This study on Pubmed shows Nattokinase can prevent blood clots, improve blood circulation, reduce hypertension, prevent stroke, and reduce the chances that you will get Alzheimer’s disease and atherosclerosis.

Most people think cholesterol causes arterial blockages and strokes/heart attacks. However, Vascular calcification is actually the primary predictor of cardiovascular morbidity and mortality.

This study on PubMed titled “Effect of vitamin K2 supplementation” shows that vitamin K2 actually reduces vascular calcification.

Natto can dramatically improve digestive health

The fermentation of the soybeans along with the high fiber in the beans adds both prebiotics and probiotics to your stomach microbiota. Natto has a huge health benefit of improving digestion and preventing Keto Constipation. One of the biggest disadvantages of the keto diet is less frequent bowel movements and occasionally eating Natto can prevent that.

The soluble fiber in natto is fermented by the bacteria in your intestinal tract and increases the formation of short-chain fatty acids, which improves gut health. Soy also contains non-starch polysaccharides (NSP) and soy pectin which, according to this study, is associated with the reduced risk of obesity.

I think it’s safe to say Natto is an amazing keto-friendly Superfood.

Natto Contains Abundant Levels of Spermidine

What is Spermidine and and is it a health benefit of Natto?

Spermidine is a class of polyamine that supports autophagy and greatly reduces inflammation. In this double blind study using 57 individuals, spermidine intake by natto elevated blood spermidine levels and inhibited pro-inflammatory status. In other words, natto lowers inflammation.

“Spermidine preserves mitochondrial function, exhibits anti-inflammatory properties, and prevents stem cell senescence.”

Spermidine in health and disease

Autophagy is a process normally initiated by fasting. It’s where the body feeds on damaged and corrupted cells allowing new cells to be regenerated. Autophagy improves longevity and helps us live longer, healthier.

Raw soybeans contain 1340 nmol/g of spermidine and natto contains 1759 nmol/g. Therefore the fermentation process actually raises the spermidine content.

Natto Can also stimulate Hair Growth

This is also pretty amazing. One of the relative unknown benefits of natto is it can stimulate new hair growth. This study in the National Library of Medicine titled, Spermidine Promotes Human Hair Growth shows that spermidine is a powerful stimulator of human hair growth and a previously unknown modulator of human epithelial stem cell biology.

Fermentation removes the anti-nutrients from the soybeans

Soybeans contain anti-nutrients and according to Wikipedia, anti-nutrients are compounds that interfere with the absorption of nutrients.

Phytic acid and Lectins are the two predominant anti-nutrients in soybeans. Lectins interfere with the absorption of nutrients in the small intestine. Phytic acid makes phosphorus and zinc less available.

The health benefits of Natto are enhanced during the fermentation process

The nutritional content of Natto is also improved during fermentation, especially vitamin K2 and probiotics.

The National Institute of Health published a study titled “Role of Fermentation in Improving Nutritional Quality of Soybean Meal.

The above-referenced research shows that the fermentation process removes the anti-nutritive compounds and improves the nutritional value of soybeans.

This study published in Science Direct shows antioxidants and phenolic compounds are also increased after fermentation as well as metal chelating activity.

How does Natto taste?

This is a tough one to answer. It has a “different” taste and can’t really be compared to other food. It’s rich, pungent, nutty and earthy. Natto tastes a little like nutritional yeast.

Natto has a slimy mouthfeel and smells a little like fermenting beer or dirty socks. It does grow on you, however, and kind of like good scotch gets better with age.

As you mix it up and pull it apart you will see what looks like spider webs. This is called “strings of natto” The strings are where most of the nattokinase is found.

It’s extremely filling, don’t put much on your plate because after just a few bites you will feel full. Make sure you have a napkin when you eat healthy natto.

How do you improve Natto’s health benefits?

Use GMO-free, organic soybeans and soak them for 24 hours in water and a little apple cider vinegar. The apple cider vinegar helps break down some of the phytic acids.

It’s pretty easy to make Natto actually. First, get you some soybeans. Try to use the smaller, non-GMO, organic soybeans. The common soybeans mass-produced today are not healthy because they contain a lot of herbicide (glyphosate) and pesticide residue.

Glyphosate-tolerant GM soy is the number one GM crop plant. The herbicide glyphosate is the most widely used herbicide in the world. The (GM) soybeans are genetically modified to resist glyphosate (Roundup Ready).

According to this article on Science Direct titled, “Glyphosate accumulates in Roundup Ready GM soybeans.” Roundup Ready GM soybeans contributed to 75% of the total soy production in 2011.

How to make Natto:

Natto is different than most other fermentations because it’s an alkaline fermentation

In alkaline-fermented foods, the protein is converted into amino acids in their peptide form. Also, ammonia is released during the fermentation, which raises the pH of the natto and gives off the distinct smell of ammonia.

Bacillus subtilis grows best in a slightly alkaline environment between a pH of 6.4-6.8. During fermentation a thin, sticky white film of bacteria is visible and a slight ammonia odor begins to develop between 18 and 24 hours.

When the ammonia odor gets too strong, the Natto might be overly fermented

Most sources that I have read recommend a fermentation temperature of between 100 and 115 degrees Fahrenheit (F). However, this source: Microbe Wiki, recommends between 115 and 120 F. The spores can actually survive up to 122 degrees F.

The Natto bacteria can also survive freezing and thawing.

Most of the nattokinase is inside the strings. The sticky “strings” come from poly-gamma-glutamic acid within the protective biofilm covering the beans.

Soybeans for Natto

Time needed: 2 days, 2 hours and 12 minutes

How to make Natto

  1. Wash beans thoroughly.

    Use clean chlorine free water.

  2. Soak beans in water and apple cider vinegar for 24 hours.

    Use 1 tablespoon apple cider vinegar per 1/2 gallon of water.

  3. Rinse and empty water.

  4. Boil beans or use a pressure cooker until beans are soft.

  5. Drain beans, but leave a little moisture in with the beans.

  6. Wash, rinse and sterilize hands, containers, and utensils with distilled cleaning vinegar.

    Rinse vinegar traces off and keep the PH between 6.4-6.8.

  7. Put warm, but not hot beans in a shallow glass pan.

  8. Inoculate beans with established Natto or use starter culture.

    Stir gently until natto threads are mixed evenly.

  9. Keep beans warm between 110-115 degrees for about 24 hours.

    A heating pad on low works well.

  10. Cover beans while fermenting with saran wrap.

    Poke holes in saran wrap so fermentation can breathe.

  11. Cover with a towel or blanket to retain heat and keep out the light.

  12. After fermentation, allow to cool slowly to room temperature and refrigerate.

Natto can be refrigerated for 2-3 weeks and also be frozen and safely kept for months and still keep its’ health benefits.

How to Make Natto

How do you eat Natto?

Any way you want. No seriously, the traditional Japanese way is to mix it up with soy sauce, mustard, and chopped green onions. Plus, Natto is a full meal in of itself but also works as a side dish.

I highly recommend adding Natto to your Keto Diet Food List.

Mixing the Natto with cauliflower rice is a good Keto-friendly way to eat it. It’s cheap, absolutely healthy and easy to make. The health benefits of Natto make it the perfect food for human health.

If you can get past the smell you’ve got it licked

Even if you don’t like the taste, the health benefits alone are reason enough to make Natto part of your keto diet. Actually, you should eat as many of the most powerful keto superfoods as possible.

Natto and similar superfoods are the key to how we look and feel

Robert Bryant
Robert Bryant

Always looking for different superfoods to improve my health I became interested in Natto. I did a lot of research on Natto and even started fermenting my own. Admittedly it doesn’t taste the best but do we want to sacrifice taste for health? Natto is both a medicine and a food.

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