Interesting analysis of traditional Japanese food natto from Fujisawa, Shinohara et all (2006).
Natto is an original and traditional Japanese food, and consists of soybean products fermented by Bacillus subtilis (‘Bacillus natto’). Various nutrients are present in the soybean, such as saponins, proteins, oligosaccharides including raffinose and stachyose, vitamin B1, vitamin E, vitamin K2 and dietary fibres. Thus, various beneficial effects of natto as a functional food are known and many medical benefits are reported. A previous study (Terada et all 1999) has indicated that natto consumption contributes to improvement of both the composition and the metabolites of the intestinal flora.
Natto is mostly prepared raw and is usually eaten with rice, but there are various ways of cooking natto, and many dishes can be prepared. One of them is miso soup containing natto (natto miso soup). Miso soup is also a traditional Japanese food, and soybean is a main ingredient. Miso is made from soybean paste fermented with yeast, mould and bacteria and then combined with salt and water.
A traditional Japanese diet not only contains little animal fat but also employs many soy foods, such as miso, natto, shouyu (soy sauce) and tofu (soy curd). There are no reports of investigations into the effects of intake of miso on faecal metabolic activities and the composition of faecal microflora, therefore in this direction further investigation is needed. But the influence of foods other than natto and miso made from soybeans on human faecal properties is also an interesting starting point of study.