7 Reasons Natto Is Super Healthy For You

Medically Reviewed by Alexandra Dusenberry, MS, RDN
Written by Ravi Teja Tadimalla, Professional Certificate In Food, Nutrition & Health

Natto benefits range from nourishing the gut to boosting the immune system. This traditional Japanese dish is considered an acquired taste as it is a slimy texture, strong flavor, and an unusual smell.

There are many other great reasons why you should serve this fermented soybean condiment with your meals. Natto is incredibly nutritious. It strengthens your bones and protects your heart. This article discusses the importance of natto, its benefits, nutritional profile, and possible side effects. Take a look.

What Is Natto?

Natto is a common breakfast option in Japan. It is a result of combining soybeans with beneficial bacteria (Bacillus subtilis) and letting them ferment for extended periods.

Natto has a powerful smell and a strong, earthy flavor. Its sticky and slimy texture is unique to it. Each batch of natto produced may taste slightly different due to the minor differences in the fermentation process. But overall, this food can help you in several ways.

How Does Natto Benefit You?

The probiotics in natto contribute to most of its benefits. These primarily enhance digestion and boost immunity. Natto is also rich in vitamin K2, an important nutrient for bone strength. It can also offer protection against cancer.

1. Enhances Digestion

Natto is replete with probiotics that boost your gut health. Studies show that having the right kind of bacteria in your gut can promote digestion and treat associated disorders (1).

Bacillus subtilis, the beneficial bacteria natto is fermented with, can treat colon mucosal inflammation and the related inflammatory bowel disease (2).

One concern with soybeans is their antinutrient content. Antinutrients are compounds that block the absorption of certain nutrients and impair digestion. Studies show that fermentation of foods (as how it happens with natto) can reduce the levels of antinutrients (3).

Consumption of enough probiotics also helps treat other issues related to digestion, like diarrhea (4).

2. Boosts Bone Health

Studies conducted on premenopausal women show that intake of natto can boost bone formation (5). Natto contains high levels of vitamin K2, a nutrient associated with improved bone turnover and bone stiffness.

Similar findings were observed in studies conducted on postmenopausal women. Menaquinone-7 in natto can boost bone mineral density and prevent the development of osteoporosis (6). Menaquinone-7 is another name for vitamin K2 (7).

3. Enhances Immunity

Studies conducted on elderly subjects show that Bacillus subtilis (the probiotic strain in natto) could stimulate the immune system and protect them from disease (8).

Similar effects were observed in studies done on calves (9).

The Bacillus subtilis in natto were also found to promote the functioning of macrophages, which are white blood cells that are an important part of the human immune system (10).

4. Promotes Heart Health


The probiotics in natto have a role to play here. Studies show that probiotics can help lower cholesterol levels – cutting down the risk of heart disease (11).

Natto also contains nattokinase, a compound concentrated in its sticky and stringy portions. Nattokinase has been found to reduce blood clots, thereby preventing cardiovascular disease (12).

Nattokinase also has anti-coagulant, anti-atherosclerotic, and neuroprotective effects – all of which contribute to heart health (13). Nattokinase has been identified as one of the rare compounds with pharmacological effects that even most drugs don’t possess.

In another study, natto extracts were also found to have anti-hypertensive effects (14). The vitamin K2 in natto also keeps calcium deposits from accumulating in the arteries (15).

Several Japanese studies also found that natto consumption was inversely associated with cardiovascular disease (16).

5. May Cut Cancer Risk

The potential cancer-preventive properties of natto can be attributed to its soy content and vitamin K2. Soy isoflavones were found to cut the risk of gastrointestinal, prostate, and breast cancers (17), (18), (19). Vitamin K2 was linked to a reduced risk of liver cancer (20).

In another Japanese study, natto was found to have anticarcinogenic effects (21).

Another report states that soy can help reduce the risk of death from stomach cancer (22). This can be attributed to the isoflavones in soy, which are particularly higher in fermented soy products – like natto.

6. May Aid Weight Loss

The probiotics in natto may contribute to weight loss. Studies show that probiotic supplementation can prevent an increase in fat mass and body mass (23).

Probiotic intake can also alter the composition of gut microbes. This improves energy metabolism, which may also aid weight loss (24).

7. Can Improve Brain Health

Several animal studies state the neuroprotective effects of fermented soybean products, like natto (25). Fermented foods enhance gut microbiota, which has a direct impact on cognitive functioning.

As we saw already, the nattokinase in natto can boost heart health. Studies show that cardiovascular health is closely linked to brain health (13).

Natto is a power food. In addition to the above-mentioned constituents, natto has other important nutrients we must be aware of.

What Is The Nutritional Profile Of Natto?

Calorie Information
Amounts Per Selected Serving%DV
Calories371(1553 kJ)19%
From Carbohydrate102(427 kJ)
From Fat161(674 kJ)
From Protein108(452 kJ)
From Alcohol0.0(0.0 kJ)
Amounts Per Selected Serving%DV
Total Carbohydrate25.1g8%
Dietary Fiber9.4 g38%
Sugars8.6 g
Fats & Fatty Acids
Amounts Per Selected Serving%DV
Total Fat19.3 g30%
Saturated Fat2.8 g14%
Monounsaturated Fat4.3 g
Polyunsaturated Fat10.9 g
Total trans fatty acids~
Total trans-monoenoic fatty acids~
Total trans-polyenoic fatty acids~
Total Omega-3 fatty acids1284 mg
Total Omega-6 fatty acids9583 mg
Protein & Amino Acids
Amounts Per Selected Serving%DV
Protein31.0 g62%
Amounts Per Selected Serving%DV
Vitamin A0.0IU0%
Vitamin C22.8mg38%
Vitamin D~~
Vitamin E (Alpha Tocopherol)0.0 mg0%
Vitamin K40.4 mcg51%
Thiamin0.3 mg19%
Riboflavin0.3 mg20%
Niacin0.0 mg0%
Vitamin B60.2 mg11%
Folate14.0 mcg4
Vitamin B120.0 mcg0%
Pantothenic Acid0.4 mg4%
Choline99.8 mg
Amounts Per Selected Serving%DV
Calcium380 mg38%
Iron15.1 mg84%
Magnesium201 mg50%
Phosphorus305 mg30%
Potassium1276 mg36%
Sodium12.3 mg1%
Zinc5.3 mg35%
Copper1.2 mg58%
Manganese2.7 mg134%
Selenium15.4 mcg22%

One cup of natto (175 grams) contains 371 calories and 9.4 grams of dietary fiber. It also contains:

  • 31 grams of protein (62% of the daily value)
  • 40.4 micrograms of vitamin K (51% of the DV)
  • 22.8 milligrams of vitamin C (38% of the DV)
  • 2.7 milligrams of manganese (134% of the DV)
  • 15.1 milligrams of iron (84% of the DV)
  • 380 milligrams of calcium (38% of the DV)
  • 201 milligrams of magnesium (50% of the DV)

No wonder natto is so popular in Japan, given its impressive nutritional profile. This takes us to a question – how do you get your hands on natto?

How To Make Natto At Home

You can find natto in most Asian supermarkets. But you can also make it at home. Here’s how:

What You Need
  • Water
  • 1.5 pounds of soybeans
  • Store-bought natto, one pack
  • A large cooking pot
  • A kitchen thermometer
  • A sterilized and oven-safe dish, with a lid
  • A pressure cooker, optional
  1. Wash the soybeans thoroughly under running water and place them in a pot.
  2. Pour the fresh water over the soybeans until they are fully submerged. Allow them to soak overnight (9 to 12 hours). You need to use three parts of water for one part of soybeans.
  3. Drain the beans the next morning and add fresh water again. Boil for about 9 hours.
  4. Now, drain the cooked beans and place them in the sterilized, oven-safe dish.
  5. Mix the store-bought natto with the boiled beans.
  6. Using a sterilized spoon, stir everything.
  7. Cover the dish and place it in an oven. Let it ferment for 22 to 24 hours at 100o F.
  8. Let the natto cool. Store it in your refrigerator for 24 more hours.
  9. Enjoy!

You can store the leftovers in the freezer for later use. You can eat natto as it is or enjoy it with steamed rice. Natto also works great in miso soup, pasta dishes, and even sushi.

Preparing natto requires some patience, and so does eating it! On that note, there are other fermented soy products like tempeh and miso. Can you consume them as well?

How Is Natto Different From Tempeh/Miso/GMO Soy?

Natto can be made with other beans too (kidney or black beans). But the beneficial bacteria thrive best on soybeans, which contributes to more efficient production of nattokinase.

Other soy products like tempeh or miso also are quite healthy – as they are made of fermented soybeans. Unfermented soy products may contain harmful compounds (phytates, trypsin inhibitors, goitrogens, phytoestrogens, and aluminum) that could be dangerous to health (26).

Talking about GMO soy, more than 90% of the soybeans we get in the US market are genetically modified. The safety of GMO foods, in general, is still under scrutiny. Research is still being done, and conclusions are yet to be formed.

Hence, we suggest you stick to the fermented versions when consuming soy. Not only are they higher in beneficial bacteria, but they also are quite low in antinutrients.

Of course, all fermented soy products offer great benefits. But it is natto alone that contains natto kinase – so you can eat more of it.

Or can you? Natto is great for most people. But some individuals are required to exercise caution.

What Are The Side Effects Of Natto?

Issues During Pregnancy And Breastfeeding

There is not enough information on the safety of natto during pregnancy and breastfeeding. Stay safe and avoid use.

Bleeding Disorders

The nattokinase in natto may act as a blood thinner and aggravate bleeding disorders. Not all studies agree with this, though (27). But recommend you talk to your doctor.

Also, avoid taking natto at least two weeks before a scheduled surgery. This is to reduce the chances of excessive bleeding during or after surgery.

Low Blood Pressure

Nattokinase may lower blood pressure levels (28). If your blood pressure is already low, this might be a problem.

Natto is a traditional Japanese food with a strong earthy flavor and sticky texture. The probiotics and essential nutrients in natto benefit your health in many ways. Natto may enhance digestion, improve bone health, boost immune system function, and promote heart health. However, the nattokinase it contains may cause hypotension and bleeding disorders in some people. In addition, avoid taking natto during pregnancy and breastfeeding as its safety in this regard is yet to be studied. Consume natto in moderation to reap its maximum benefits.


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Alexandra Dusenberry

Alexandra Dusenberry is registered dietitian nutritionist and certified personal trainer based in San Diego, California. She works with clients around... more