Natto is an ancient Japanese food made from the Natto soybeans. Natto is soaked and fermented, which makes the soybeans quite sticky, and produces a springy or web effect between each bean. It can be an acquired taste because the fermenting process makes the smell of natto very strong, and to some not used to the dish, unpleasant. It also tends to produce bad breath, though a vigorous tooth brushing using removes the traces that one has been snacking on natto.

In certain parts of Japan natto holds great popularity. It may be eaten as a breakfast food, sometimes with a little sugar, or may be served over rice. Some prefer to add sauces to natto and rice, and may use different hot mustards, soy sauce, quail eggs or grated radishes as a topping. It is quite nutritious and low in calories. It has about 7-8 grams of protein per serving, and each serving only has about 90 calories.

Natto is also celebrated for its high amounts of vitamin K, which makes it an outlaw food for those taking warfarin (brand name Coumadin®). It also is high in a number of anti-oxidants, particularly selenium. Natto also contains a protein called nattokinase, which may be a natural blood thinner. Since natto allows the soybeans to ferment and grow bacteria, it is also a probiotic food.

The traditional method for preparing natto dates back at least 3000 years, and some food historians suggest natto may have been prepared 10,000 years ago. Some suggest Natto may first have been Chinese in origin, but it is now considered a primarily Japanese food. Stories about the origins suggest that natto may have been discovered accidentally when soldiers in a hurry packed leftover cooked soybeans and didn’t open them again for several days.

Today one doesn’t have to carry cooked soybeans around in order to make natto. In fact most purchase premade natto and do not make their own. It is usually prepared by adding the bacteria bacillus natto, which quickly produces the sticky soybeans and the strong smell.

Many who try natto for the first time find the flavor to be nutty and a bit sharp, better tasting than smelling. Others feel most natto is bland and think it needs additional flavoring. For those who can’t get past the smell, there are some companies that have produced low odor natto, and these might be more palatable.

Not every person in Japan enjoys natto either. It is most popular in Eastern Japan. It’s also hard to find natto outside of Japan, though occasionally Asian markets will stock it in the frozen section. One might also find natto ice cream or dried natto, which is eaten like nuts or chips. In Korea, a similar dish to natto includes fermented soybeans and is called cheongguikjang. The Chinese also make a fermented black bean dish called douchi.