We have a traditional fermented soybean dish from Japan called natto. Natto is believed to have originated about 1,300 years ago in Ibaraki, a soybean-producing area of Honshu, Japan.

It is a very loved cuisine in Japan and slowly gaining popularity in the Western world due to its nutritional importance and health benefits as soybeans undergo a process of fermentation. Our readers must be wondering what fermented soybean is.

Fermentation is used to preserve and enhance the shelf life of food and is a biological process where carbohydrates break down into lactic acid and CO2 during anaerobic conditions. During soybean fermentation, the nutrients are broken down into fatty acids, various amino acids, and isoflavones.

That was the technical information. Now let’s understand how natto is made. The process involves, first, soaking and cooking soybeans. Then they are mixed with Bacillus subtilis to allow fermentation for up to 24-36 hours at 40 degrees.

After cooling, it’s aged and then refrigerated for up to a week to enable the growth of stinginess. ¹https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9616652/ This is why natto is sticky with a very unusual earthy texture, slightly bitter and a pungent fragrance that makes it easy to identify. There are three classes of natto:

-Hamanatto
-Itohiki
-Daitokuji natto.

In Japanese homes, it’s eaten with rice, seasoned toppings like soy sauce, seaweed, mustard, and other condiments and is served between courses. The introduction might not tickle your taste buds, but let me tell you why natto is good for you, and I am sure that by the end of the article, you will start looking at the natto recipes.

Natto has a nutritional profile as a superfood for many reasons. As a fermented food item, it is probiotic and good for our gut. Many studies have linked diets high in fermented foods with weight maintenance and decreased risk of diabetes, cancer, cardiovascular risks and molecular signs of inflammation. ²https://www.cell.com/cell/fulltext/S0092-8674(21)00754-6, ³https://pubmed.ncbi.nlm.nih.gov/34256014/, ⁴https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9530890/, ⁵https://www.mdpi.com/2304-8158/12/4/687

Let’s look at the nutritional composition of 100g of natto: ⁶https://fdc.nal.usda.gov/fdc-app.html#/food-details/172443/nutrients

Calories: 211
Protein: 19g
Fat: 11g
Fiber: 5.4g
Vitamin C: 13mg
Iron: 8.6mg
Potassium: 729mg
Calcium: 217mg

After the nutritional content, let’s look at how healthy natto is.

Natto is rich in protein, vitamins and minerals and a potent enzyme is produced because of fermentation called ‘nattokinase.’ Natto is the only natural food source of nattokinase and the highest plant source of vitamin K2.

Natto is also incredibly nutritious as soybeans undergo a fermentation process, creating conditions that promote the growth of probiotics. ⁷https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9616652/

Below are a few of the health benefits of natto:

Boosts Digestion

Natto is a natural dietary source of probiotics. Research has proven that good gut bacteria can facilitate digestion, help reduce gas, bloating, and constipation, and ease symptoms of I.B.D, Crohn’s disease and ulcerative colitis. ⁸https://www.gastrojournal.org/article/S0016-5085(20)34729-6/fulltext, ⁹https://pubmed.ncbi.nlm.nih.gov/32005532/, ¹⁰https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5900870/

Related Article: Probiotics For Gut Health | 9 Probiotics-Rich Foods

Soybeans contain antinutrients, but the fermentation process of making natto reduces the number of antinutrients and facilitates their digestion. ¹¹https://pubmed.ncbi.nlm.nih.gov/28975646/

May Protect Heart Health

Nattokinase is an enzyme produced by the bacterium Bacillus subtilis during the fermentation process of soybeans. It is a potent blood-clot-dissolving protein used to decrease the risk of CVD mortality. ¹²https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6043915/, ¹³https://pubmed.ncbi.nlm.nih.gov/27927636/, ¹⁴https://pubmed.ncbi.nlm.nih.gov/18971533/, ¹⁵https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5066864/, ¹⁶https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5372539/, ¹⁷https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5066864/

May Promote Bone Health

Natto is high in vitamin K2, which may help improve bone mineral density and prevent osteoporosis. Studies on premenopausal women have shown that natto may improve bone growth. ¹⁸https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7645307/, ¹⁹https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9403798/

Natto’s probiotic properties may promote weight loss, improve cognitive health, strengthen the immune system, reduce cancer risk, and enhance digestion. ²⁰https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4669646/, ²¹https://pubmed.ncbi.nlm.nih.gov/29805627/, ²²https://www.researchgate.net/publication/363398847_Nutritional_and_Health_Perspective_of_Natto_A_critical_review, ²³https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9616652/ Hope our readers will consider adding natto and other fermented soya products like miso to their diet.

Have any of you ever wondered how natto is different from miso?

Natto and miso are fermented soybean food products but differ in many ways.

Similarities

-Fermented soybean-based foods

-Japanese staples

-Umami or acquired flavor

Differences

-Fermentation Process

Both are fermented, but natto starter contains the bacteria Bacillus subtilis and miso starter includes a type of fungus called Aspergillus oryzae (koji mold). 

-Texture

Natto soybeans retain their shape and crunchy texture, whereas miso is a smooth paste.

-Timing

Natto fermentation takes 24-36 hours, whereas miso can take weeks to months.

-Nutritional value

Both foods have high nutritional value, and natto may offer more health benefits, but miso has a broader culinary range. Therefore, one can include both in the diet in moderation. 

Natto is generally safe, but the enzyme’s dominant effect may affect individuals taking blood thinning medication or with thyroid problems. Therefore, it would be advisable to consult the doctor before including natto in the diet.

The bottom line is that natto is also an excellent source of protein for vegans or anyone following a plant-based diet, and eating it may strengthen the immune system and improve the gut microbiome.

It is a good idea to add this excellent probiotic to your diet, however, please consult your physician in case you have any food allergies before you do. Good luck! 🙂