Vitamin K and Natto - What's the Connection?

Natto is one of the richest sources of vitamin K2, which is important for bone and heart health. Here's what you need to know about this little-known nutrient and even lesser-known food source. 

Monica Reinagel, MS, LD/N, CNS
4-minute read
Episode #273

What Is Natto?


Natto is made from fermented soybeans.  Although it's a daily staple for many Japanese, most Westerners have never heard of it, much less tried it. Like many fermented foods, natto has a somewhat strong flavor and aroma. Some might even describe it as "funky."  Let's just call it an acquired taste.

If you want to try it, I suggest first preparing it in the traditional Japanese way. Here's how a friend who grew up with a Japanese mom once made it for me: 

Whisk together 1 raw egg, 4 tablespoons low sodium soy sauce, 1 teaspoon sesame oil, 1 teaspoon prepared mustard or wasabi, and 1 finely chopped green onion. Combine natto with the sauce mixture and spoon over hot white rice. The result is a flavorful, savory dish that you can enjoy as a light lunch, snack, or appetizer. 

In addition to being a potent source of vitamin K2, natto is also a good source of protein, fiber, and isoflavones.

See also: All About Soy


In addition to being a potent source of vitamin K2, natto is also a good source of protein, fiber, and isoflavones.

You can vary the proportions of soy sauce, sesame, and mustard to suit your taste. Although the raw egg is traditional (and does a lot to mellow the flavor of the raw natto), you can omit this if you have any concerns about eating raw eggs -- or use eggs that have been pasteurized in the shell.

See also: Foods to Avoid During Pregnancy


Where to Find Natto?

You'll find natto at Asian grocers or health food stores. It's usually sold frozen or in vacuum-sealed pouches. If you can't find it locally, there are several online Japanese and Asian grocers who can ship it to you. Natto is very inexpensive, about $1 per serving.  Serious do-it-yourself-ers can even make natto at home, using dried soybeans and natto spores.  Natto spores and instructions are available from www.culturesforhealth.com

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About the Author

Monica Reinagel, MS, LD/N, CNS

Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes' most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation's leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show.