Natto (pronounced nat-oh) is a traditional Japanese food made by fermenting soybeans. Natto has been a popular and nutritious food in Japan for centuries and is known for its possible therapeutic effects on heart disease. A soybean based diet is thought to be one of the reasons for the low rate of heart disease in Japan.
Natto has a distinctive, powerful smell that has been described as musky and similar in pungency to ripe cheese. It often comes wrapped in rice and seaweed. Natto has a strong, nutty and salty flavor and a slippery texture. In Japan, it is often eaten at breakfast with rice and, sometimes, with mustard, soy sauce, broth, vegetables or a raw egg. In that country you’ll also find natto sushi, natto toast and in some areas, natto dusted with sugar, even natto ice cream.
Because of its pungent odor, odd texture and assertive flavor, it’s a challenging food for most westerners (and some Japanese as well) to enjoy. Personally, I’ve come to like it occasionally, especially with sushi.
To make natto, soybeans are soaked overnight and then steamed for about an hour. Next they’re sprinkled with powdered natto bacteria (Bacillus subtilis) and allowed to ferment for up to 24 hours. It then must be cooled and aged for at least a week to allow its characteristic flavor and texture to develop.
Like other fermented soy foods, natto contains vitamin K, which we need for normal blood clotting and regulation of calcium in the body, keeping it in the bones and out of the arteries. Adequate vitamin K intake also appears to reduce the risks of both heart disease and cancer. In addition, natto provides vitamin E and vitamin B2 and contains an enzyme called nattokinase, produced during the fermentation process, which is said to help prevent blood clots and which is being studied for it health benefits.