I'm a fan of a traditional Japanese dish called Natto. In my free time, I like to make natto using a simple proofing oven. Below are a few facts about this little-known Japanese superfood.

What is Natto?

Natto is fermented soybeans.


The origin of natto is not definitive. One story claims that natto originates as far back as 300BC. The first consumption of natto was likely an accident. It was the result of using rice straw to store boiled soybeans during cold winters or travel. Rice straw contains a bacteria called Bacillus subtilis which is the bacteria needed to make natto.

One notable change in natto production happened during the Taisho period (1912-1926). Researchers found a way to produce the starter culture without the need of rice straw. This simplified production and permitted more consistent results. Now, there are over 900 companies in Japan that are licensed to produce natto. The main natto-producing area is in Ibaraki Prefecture, just north of Tokyo.

The etymology of the term natto is composed of two characters. The first means “to offer” and the second means “beans”.

Health Benefits

Natto is an excellent source of protein, fiber, vitamins, and minerals. Additionally, Bacillus subtilis creates an enzyme called nattokinase which produces vitamin K2.

In one cup of natto, you get the following minerals (percentages based on a daily recommended diet):

  • Protein: 31.0 g
  • Manganese: 134%
  • Iron: 84%
  • Copper: 58%
  • Magnesium: 50%
  • Calcium: 38%
  • Potassium: 36%
  • Zinc: 35%
  • Phosphorus: 30%
  • Selenium 22%

You also get the following vitamins:

  • Vitamin K: 51%
  • Vitamin C: 38%
  • Riboflavin: 20%
  • Thiamin: 19%
  • Vitamin B6: 11%
  • Folate: 4%
  • Pantothenic Acid: 4%

Vitamin K2

One of Vitamin K2’s benefits is bone health. K2 helps get calcium out of your bloodstream from your diet into your bones. According to the National Institutes of Health, it is a key component in maintaining the bone mineral density of postmenopausal women suffering from osteoporosis. The role that K2 plays in supporting proper calcium levels throughout the body is crucial. This intrinsically supports your bloodstream too since it helps regulate calcium in your bloodstream and even reverses the calcification of arteries. Vitamin K2 is also known to prevent age-related neurological degeneration and kidney stones.

Nattokinase Enzyme

The Nattokinase enzyme is the enzyme produced by B. subtilis and it also has cardiovascular health benefits. Nattokinase has been shown to dissolve blood clots and is also known as a “natural blood thinner”. It has been sold in a pill form for many years in the US. In its pill form, it is commonly used to help prevent stroke and progression of cardiovascular disease. The main benefits of this enzyme include:

  • Blood clots
  • Beriberi (B vitamin deficiency)
  • Cancer
  • Chronic fatigue syndrome
  • Endometriosis
  • Fibromyalgia
  • Infertility
  • Pain
  • Muscle spasms
  • Uterine fibroids

Probiotic health

B. subtilis is an important natural resident of the healthy human gut. It has been shown to promote the growth of other beneficial microbes and to inhibit potentially harmful microbes.

B. subtilis supports digestion, aids in enzyme production, and helps balance the gut. It is able to withstand the gastrointestinal tract thanks to its ability to survive under stressful conditions. Enzymes and probiotics have a symbiotic relationship. Both are critical to gastrointestinal health. Enzymes help create a favorable environment for probiotics, and probiotics help the production of beneficial enzymes in the gut. In fact, before antibiotics became widely available, B. subtilis was used to treat gastrointestinal problems.