Fresh, Homemade Natto Recipe

Recipe From Dr. Mercola

Natto, which is essentially fermented soybeans, is one of Japan’s most unique health foods that has a history going back to more than 1,000 years ago. Records are unclear how natto was created, but there are several theories. One popular story involves Hachiman Taro Yoshiie, a general during the Heian period (794 to 11851).

One night, Hachiman’s soldiers were cooking soybeans to feed their horses, but they were suddenly attacked. In a panic, they hurriedly packed the food in a tawara (rice straw sack) tied to the back of a horse. A couple of days later, they discovered that the warmth of the horse’s body fermented the beans. They gave it a try and liked it — from there, natto was born.2 Today, this dish is enjoyed all over Japan, and it’s estimated that a whopping 700,000 tons of it are produced annually.3

As you know, I don’t generally advise eating soy products since they are related to various health problems. However, natto is one of the few soy dishes I recommend. The fermentation process removes the disadvantages associated with eating raw or cooked soy, so you’re left with a dish that is filled with probiotics and nutrients that can help optimize your health. If you haven’t tried natto before, I urge you to give this recipe a try.

Fresh, Homemade Natto Recipe


  • 1 pound of organic soybeans
  • 0.1 grams of Bacillus natto bacteria powder or substitute 1 package of store-bought natto


  1. Wash the soybeans and soak them for about 24 hours.
  2. Steam the soybeans for three to six hours, until you can easily crush them. Drain.
  3. Just before the soybeans are done cooking, sterilize all of your utensils, bowls and natto containers (large, flat casserole dishes work well) by dipping them into a pot of boiling water. Also make sure your hands are clean.
  4. Pour the soybeans into a sterilized bowl.
  5. Mix the bacteria powder with 2 tablespoons boiled water (that you have then allowed to cool) until it’s dissolved. Pour the mixture over the soybeans and stir well.
  6. If you are using store-bought natto, add it to a small amount of pre-boiled, then cooled, water and stir until it forms a paste. Pour the paste over the soybeans and stir well. You want a ratio of about 5 to 10 percent natto to 90 to 95 percent cooked soybeans.
  7. Transfer the beans into your sterilized dishes. Place them in a thin layer, no more than 1 inch high.
  8. Place a sterilized linen cloth or cheesecloth over the dishes, then secure in place with clips or a large rubber band around the edge.
  9. Put the dishes into your oven (turned off) with the light on. The light should heat the oven just enough to keep the temperature between 99 or 108 degrees Fahrenheit. This is the temperature you need for proper fermentation.
  10. Place a thermometer in the oven to monitor the temperature. If it’s too cool, add a work lamp to the bottom of the oven fitted with a 40- or 60-watt bulb, depending on how much heat you need.
  11. Keep the beans between 99 to 108 degrees Fahrenheit for 22 to 24 hours.
  12. Remove the clips or rubber band (but leave the cloth) and place the dishes into your refrigerator. Refrigerate it overnight before eating.

Note: Natto can be kept in your refrigerator for up to one week. You can also freeze it for up to two months.

The Pitfalls of Consuming Unfermented Soy

For a long time, soy manufacturers have spent big bucks promoting their products, backing up the ads by citing paid studies that omitted any possible harms. But despite what they say, consuming soy, especially in large amounts, can be bad for your health because it contains:

Antinutrients that can block trypsin, an enzyme essential for protein digestion4

Hemagglutinin that can promote unwanted blood clotting. Too much of it can make your red blood cells clump together and inhibit oxygen uptake and growth5

Phytates that can prevent the proper absorption of crucial minerals such as calcium, magnesium, zinc and iron6

Goitrogens that can block your body’s ability to synthesize thyroid hormones and interfere with iodine metabolism7

Phytoestrogens that can disrupt endocrine function, and may even increase your risk of infertility8

Genetically modified traits that can interfere with your digestive health9

While this list may turn you away from soy, you should know that it can actually be healthy for you, but only if it is fermented. The fermentation process reduces soy’s phytate and antinutrient levels, making it beneficial for your health.

Fermenting Brings Out Soybeans’ Health Benefits

Soybeans are turned into natto by fermenting them in Bacillus natto, the probiotic at the center of this dish. Take note that you cannot create natto without a starter culture. If you don’t have it, you will end up with just boiled soybeans. That being said, research has discovered that natto can benefit your:

  • Heart Health

    Natto contains a special enzyme called nattokinase, which was discovered by Dr. Hiroyuki Sumi at the University of Chicago. It has been found to help lower the risk of blood clots forming in your vessels because it mimics the function of plasmin, a natural enzyme in your body that counteracts fibrin. Too much fibrin in your blood can cause your body to form unnecessary blood clots, increasing your risk of stroke or a heart attack.
  • Blood Clotting Function and Bone Health

    Vitamin K2 is a naturally occurring nutrient produced during the fermentation of soybeans, and is essential in helping your immune system develop proper blood clotting, as well as helping to prevent atherosclerosis (aka hardening of your arteries). This vitamin is also essential in the formation of healthy bones, because it helps produce osteocalcin, a special protein that acts as a glue to incorporate calcium into your bones.
  • Antioxidant Capabilities

    Natto is rich in PQQ (pyrroloquinoline quinone), a special vitamin that helps produce additional mitochondria, as well as protecting them from free radicals. As a result, you produce more energy for your day-to-day needs.10
  • Weight Management

    If you’re trying to keep your weight within a healthy range, natto is a good choice for you. It’s high in fiber, which can help you feel full longer and promote a healthier digestive tract. It is also low in calories, making it a great dish for those who monitor their calorie intake.11

The Different Ways You Can Enjoy Natto

Natto is an acquired taste because of its pungent flavor and aroma, which sometimes has been compared to dirty socks. It also doesn’t have an appealing appearance. These two factors make it quite hard for most people outside Japan to enjoy the dish.

Even I had difficulties when I was just starting to eat natto. Through experimentation, I was able to find a combination that worked well to my taste. I mix organic yellow mustard, chopped raw onions, grapeseed mayonnaise and a dash of Himalayan salt to my homemade natto. Now, I enjoy it and look forward to the next time I eat it.

If you tried plain natto and do not like the flavor, there are ways to help improve the taste. I recommend using organic soy sauce or hot mustard to modify the flavor. You can try my combination above or you can mix natto with other foods such as:12

  • Kimchi
  • Raw egg
  • Green onions
  • Japanese ginger

Japanese travel magazine MATCHA also recommends adding natto to other dishes such as Japanese curry and tempura.13 However you choose to eat natto, adding it to your diet can optimize your health, because the benefits are just too good to ignore. It might take some time to get used to the taste, but you will eventually enjoy it like I do.

+ Sources and References