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?

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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 osteoporosisⁱ  XA condition where the bones weaken as their mineral density decreases, increasing the risk of fractures. (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 macrophagesⁱ  XA kind of white blood cell that detect and destroy any foreign substance entering the body. , which are white blood cells that are an important part of the human immune system (10).

4. Promotes Heart Health

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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-coagulantⁱ  XChemicals (also called blood thinners) in the form of medicines that prevent the development of blood clots , 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-hypertensiveⁱ  XThe property of a substance or medicine to regulate high blood pressure, thus minimizing the risk of heart and kidney issues. 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 isoflavonesⁱ  XCompounds produced by plants (mostly found in the bean family), which emulate the estrogen hormone. 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 anticarcinogenicⁱ  XA chemical substance that works to delay the progress and development of cancer. 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

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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?

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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

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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

Directions

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.

Frequently Asked Questions

Is it okay to eat natto everyday?

Yes, it is okay to eat natto everyday. However, natto should be consumed in moderate quantities to avoid side effects such as weight gain, cardiovascular issues and issues with blood clotting.

What is the best time to eat natto?

Opinion is divided with regards to the best time to eat natto. Traditionally, it is served as part of a breakfast meal. When consumed in the morning, it can increase your metabolism and give you energy for going through the day. When consumed at night, its blood pressure lowering effects are less likely to cause problems and it may facilitate the breakdown of blood clots in the body (29), (30).

Is natto anti-aging?

Yes, research shows that natto exhibits antiaging effects on the cells of the body (31). However, more human studies are warranted in this regard.

Does natto increase estrogen?

Natto contains phytoestrogens, which mimic the action of estrogen, and may cause an apparent increase of estrogen in the body (32), (33).

Does natto make you gassy?

Being a fermented food, natto generally does not cause gas and bloating. However, overconsumption of natto may cause gastrointestinal discomfort.

References

1. “The gut microbiota and inflammatory…” The Journal of Allergy and Clinical Immunology, US National Library of Medicine.
2. “Effect of bacillus subtilis…” Indian Journal of Biochemistry & Biophysics, US National Library of Medicine.
3. “Reduction in antinutritional and toxic components…” Food Research International, ScienceDirect.
4. “Probiotics for the prevention and treatment of…” JAMA, US National Library of Medicine.
5. “Promotion of bone formation by…” Journal of Nutritional Science and Vitaminology, US National Library of Medicine.
6. “Intake of fermented soybeans, natto, is associated…” The Journal of Nutrition, Oxford Academic.
7. “Menaquinone-7” Open Chemistry Database, US National Library of Medicine.
8. “Probiotic strain Bacillus subtilis…” Immunity & Ageing, US National Library of Medicine.
9. “Effects of bacillus subtilis natto on performance…” Journal of Dairy Science.
10. “Immunomodulatory effects of bacillus subtilis…” Microbiology and Immunology, Wiley Online Library.
11. “Cholesterol-lowering probiotics as potential…” Experimental Diabetes Research, US National Library of Medicine.
12. “A single-dose of oral nattokinase potentiates…” Scientific Reports, US National Library of Medicine.
13. “Nattokinase: a promising alternative in prevention…” Biomarker Insights, US National Library of Medicine.
14. “Anti-hypertensive substances in fermented…” Plant Foods for Human Nutrition, US National Library of Medicine.
15. “Vitamin K dependent proteins and the role of…” Oman Medical Journal, US National Library of Medicine.
16. “Dietary soy and natto intake and cardiovascular…” The American Journal of Clinical Nutrition.
17. “Soy and isoflavone consumption and risk of…” European Journal of Nutrition, US National Library of Medicine.
18. “Isoflavones and prostate cancer…” Chinese Medical Journal, US National Library of Medicine.
19. “Soy and its isoflavones…” Anticancer Agents in Medicinal Chemistry, US National Library of Medicine.
20. “Effect of menatetrenone, a vitamin K2 analog…” International Journal of Cancer Research and Treatment.
21. “Re: soy, isoflavones , and…” Journal of the National Cancer Institute.
22. “A prospective cohort study of soy product…” British Journal of Cancer, US National Library of Medicine.
23. “Probiotic supplementation attenuates increases…” Obesity, US National Library of Medicine.
24. “Lactobacillus fermentum and…” Journal of Functional Foods, ScienceDirect.
25. “A review of fermented foods with beneficial…” Preventive Nutrition and Food Science, US National Library of Medicine.
26. “Role of fermentation in improving…” Asian-Australasian Journal of Animal Sciences, US National Library of Medicine.
27. “Nattokinase: a promising alternative in prevention…” Biomarker Insights, US National Library of Medicine.
28. “Effects of nattokinase on blood pressure…” Hypertension Research, US National Library of Medicine.
29. “Consumption of nattokinase is associated with reduced blood pressure and von Willebrand factor, a cardiovascular risk marker: results from a randomized, double-blind, placebo-controlled, multicenter North American clinical trial…” Integrated Blood Pressure Control, US National Library of Medicine.
30. “Nattokinase: An Oral Antithrombotic Agent for the Prevention of Cardiovascular Disease…” International Journal Of Molecular Sciences, US National Library of Medicine.
31. “Natto (fermented soybean) extract extends the adult lifespan of Caenorhabditis elegans…” Biosci Biotechnol Biochem, US National Library of Medicine.
32. “The pros and cons of phytoestrogens…” Front Neuroendocrinol, US National Library of Medicine.
33. “Soy and Health Update: Evaluation of the Clinical and Epidemiologic Literature…” International Journal Of Molecular Sciences, US National Library of Medicine.

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— Update: 17-03-2023 — cohaitungchi.com found an additional article Natto Nutrition Facts and Health Benefits from the website www.verywellfit.com for the keyword health benefits of natto.

Natto is fermented soybeans. Often consumed as a breakfast food, the brown, sticky, concoction has a distinctive smell that can be compared to a pungent cheese. The powerful flavor is often described as earthy or nutty and somewhat bitter. While the food is most commonly consumed in Japan, it is slowly making its way into markets in the U.S. and other western countries due to its health benefits.

Natto is considered a superfood for several reasons, including its potential effects on the digestive system. Soybeans provide well-documented nutritional benefits. Studies are ongoing about the impact that natto has on overall health and wellbeing.

Nutrition Facts

The following nutrition information is provided by the USDA for one cup (175 grams) of natto.

Carbs

There are different types of carbohydrates in natto. Each type provides different benefits.

You'll get about 6 grams of naturally-occurring sugar if you consume one cup of natto. Sugar that occurs naturally in foods is less of a concern than sugars that are added to food as part of processing (called “added sugars”). Sugar provides the body with energy for daily activities.

Another form of carbohydrates in natto is fiber. You’ll get over nine grams when you consume a full cup of the fermented food. The USDA recommends that adults consume 28 grams of fiber per day. Consuming fiber not only improves digestion and regularity, but it also provides many other health benefits, including decreased risk of some types of cancer, obesity, cardiovascular disease, and diabetes.

The remaining carbohydrate in natto is starch, which is broken down to provide fuel for your brain and muscles.

The glycemic load (GI) of natto is estimated to be nine when one cup is consumed. Glycemic load takes portion size into account when estimating a food's impact on blood sugar. However, natto is often consumed with rice—a higher glycemic food. The University of Sydney estimates the glycemic load of a 150-gram serving of white rice and natto to be 24. Foods with a glycemic load of 20 or higher are considered to be high glycemic foods.

Fats

Natto provides just over 19 grams of fat in a one-cup serving. Most of that fat is polyunsaturated. Polyunsaturated fats help reduce low-density lipoprotein (LDL) cholesterol and can help lower your risk of heart disease and stroke. Natto also provides about four grams of monounsaturated fat—also considered a “good” fat. And there are just under three grams of saturated fat in natto.

Protein

Natto is a high-protein food. You'll boost your intake of plant-based protein by 34 grams when you consume a full cup.

Vitamins and Minerals

Natto is packed with micronutrients. A serving of natto provides 2.7mg of manganese, a whopping 134% of your daily recommended intake. Manganese is important for enzyme function in the body and other functions including blood clotting and metabolism.

You'll also get about 15 grams of iron (84% of your daily needs), 1.2 mg of copper (58% of your daily needs), 201 mg of magnesium (50%), 1,276 mg of potassium (36%), 5.3 mg of zinc (35%), 305 mg of phosphorus (30%), and 15.4 mcg of selenium (22%).

You'll also benefit from the vitamins that natto supplies. The food is high in vitamin C, providing almost 23 mg or about 38% of your daily needs. Vitamin C helps to boost your body's immune system, build collagen, and improve the absorption of iron from plant-based foods. It is also an antioxidant that can help your body repair the damage from free radicals.

Natto contains 0.3 mg of thiamin (19% of your daily needs), 0.3 mg of riboflavin (20%), vitamin B6, folate, and choline.

Lastly, natto is often cited as one of the best sources of vitamin K, particularly vitamin K2. Your body uses vitamin K to form bone and prevent blood clotting. The National Institutes of Health recommends that adult women get at least 90 mcg of the vitamin per day and men get at least 120 of vitamin K per day. A one-cup serving supplies over 40 micrograms of vitamin K.

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Health Benefits

Natto has been studied for a wide range of benefits that the food may provide. These are some of the most significant findings.

Provides Gastrointestinal Benefits

Natto is fermented with a specific type of bacteria called Bacillus subtilis. Researchers are studying the potential of this and other Bacillus strains to improve gut health in humans. They do know that this bacteria provides probiotic benefits.

There is some limited evidence that consuming natto and other fermented foods may positively influence stool frequency, especially in those managing constipation. More trials need to be conducted to further understand the benefit.

Might Improve Bone Density

Vitamin K2, found in natto, is showing promise in the management of several conditions including diabetes, cancer, and particularly osteoarthritis.

One study published in Osteoporosis International examined the impact of natto intake on the bone health of elderly Japanese men. After studying over 1,600 men, researchers found that those who consumed more natto experienced increased bone health as a result of the vitamin K content. However, researchers noted that more studies are needed to understand the association.

Another study examined natto consumption in older women. For the study, 944 postmenopausal Japanese women were studied over the course of three years.

Interestingly, the researchers did not see this benefit with increased intake of tofu or other soybean products.

Improves Cardiovascular Health

Nattokinase is an enzyme produced in natto during the fermentation process. It acts as a natural blood thinner and assists in the prevention of arterial plaque formation.

Researchers have found that nattokinase may provide cardiovascular benefits including a reduction in the risk of cardiovascular disease. More specifically the enzyme has demonstrated antihypertensive, anti-atherosclerotic, and lipid-lowering, anti-platelet, and neuroprotective effects, according to several research studies.

May Improve Longevity

Because nattokinase has been linked to substantial reduction in the risk for cardiovascular disease, researchers have also linked it to improved longevity. Cardiovascular disease is the leading cause of death in the world.

According to the authors of a 2018 study, “natto consumption is believed to be a significant contributor to the longevity of the Japanese population. Recent studies demonstrated that a high natto intake was associated with decreased risk of total cardiovascular disease mortality and, in particular, a decreased risk of mortality from ischaemic heart diseases.

May Lower Blood Pressure

Many studies involving natto are conducted on people living in Japan, where the food is more commonly consumed. But one study involved 79 participants with elevated blood pressure, all living in North America. Researchers found that consumption of nattokinase was associated with a reduction in both systolic and diastolic blood pressure in both men and women. The data collected from women suggested a possible reduction of risk for stroke.

Allergies

The Centers of Disease Control and Prevention has identified eight major food allergies in the United States. Soy is one of them. The others are milk, egg, peanut, tree nuts, wheat, fish, and crustacean shellfish. Those with a soy allergy should avoid natto.

The Cleveland Clinic also identifies symptoms in adults including itching, hives, eczema, swelling of the lips, tongue, or throat, chest tightness or difficulty breathing, wheezing, dizziness, fainting and in severe cases, anaphylaxis. Children with soy allergies may experience chronic vomiting, diarrhea, and failure to gain weight or height, according to the National Institute of Allergy and Infectious Disease.

Adverse Events

Soy may interact with certain medications. Memorial Sloan Kettering Cancer Center identifies several medications and classes of medication that may interact with soy. They include:

• Aromatase inhibitors
• Cytochrome P450 substrate drugs
• P-Glycoprotein substrate drugs
• Tamoxifen
• Uridine 5’-diphospho-glucuronosyltransferase (UGT) substrate drugs

If you are not sure if your medication falls into one of these categories, speak to your healthcare provider to get personalized advice.

There has also been some concern about the impact of soy on women's health. Specifically, some are concerned that soy consumption may increase the risk of endometrial hyperplasia. However, the National Institutes of Health advises that soy foods do not appear to increase the risk of the condition. Furthermore, the agency states that it is safe for women who have had breast cancer or who are at risk for breast cancer to eat soy foods.

Lastly, some people are concerned about antinutrients in soybeans. Antinutrients are compounds that interfere with nutrient absorption. Antinutrients can also and cause gastrointestinal discomforts such as bloating and gas. The term “antinutrient” is misleading as they have an effect only when consumed in extremely large quantities. Additionally, the fermentation process reduces antinutrients in food.

Varieties

There are different varieties of natto, each distinguished by the fermentation process, the variety of soybean, and the soybean size. At an Asian market, you might see large, medium, and small natto for sale. Hikiwari natto is another variety that is widely known. Hikiwari is natto that has been pulverized before the fermentation process.

When It’s Best

Natto is available year round.

Storage and Food Safety

Natto can be stored for months in the refrigerator, where it continues to ferment. It should be covered with cheesecloth and stored in an airtight contain to maintain the food's moisture level. Natto can also be frozen. While natto can last a long time, there is a point when the beans start to go bad. When natto accumulates tiny white dots, it is time to throw it away.

How to Prepare

Natto lovers say that the flavor is an acquired taste. But those that enjoy this food say the extra effort is worth it. The food contains glutamate which the tongue perceives as umami. Umami is considered to be the fifth basic taste and is described as both satisfying and savory.

Most people don't eat natto alone. It is usually consumed on white rice. But some also eat the food on top of toast or pasta. It can also be added to foods including miso soup, salads, or other Japanese dishes such as tamagoyaki (omelet) or okonomiyaki (savory pancake).

Try adding ingredients to natto to enhance the flavor. When sold in Asian convenience stores, mustard and a special Japanese sauce are usually included. You can also add soy sauce, raw egg yolk, chives, green onion, sliced dry bonito, kimchi, wasabi, cheese, mayonnaise, seaweed, peppers, or tuna.

Natto aficionados recommend that you mix the beans thoroughly before eating. When it develops a sticky texture then it is ready to eat.