Vitamins K2, B6 and B2
This section covers some of the nutritious components produced in the course of soybean fermentation by the natto bacillus.
* The following information is based on the 2020 Standard Tables of Food Composition in Japan, 8th revision.
Natto is known to be a food that is particularly rich in vitamin K2, containing 600 µg per 100g. This quantity of vitamin K2 in natto is an astonishing 85 times that contained in boiled soybeans.
In terms of human health, the most important of the functions of vitamin K2 is its role in bone formation. Vitamin K2 strengthens the binding of calcium, the primary component in bones, and acts to stop its elution from bones. There are data showing that people who suffer from osteoporosis have a lower concentration of vitamin K2 in their blood. Vitamin K2 formulations are used in therapeutic medications that have the potential to increase bone density and prevent bone fractures.
On other function of vitamin K2 is increasing blood coagulation. In Japan, newborn infants are fed a syrup into which vitamin K2 has been dissolved. This is done to prevent neonatal bleeding disorders. In the field of perinatal medicine, it is known that an infant's blood coagulation can be increased by having the breastfeeding mother eat natto.
* Journal of the Japan Society of Home Economics "Water Soluble Vitamin K2 Complexes in Natto"
Natto contains approximately 2.4 times the quantity of vitamin B6 per 100g as compared to boiled soybeans.
In the human body, vitamin B6 is related to the metabolism of more than 100 proteins and amino acids. It is also involved in cerebral development in the womb and during infancy, as well as immune functions. A vitamin B6 deficiency can cause anemia, eczema and chapping of the lips and mouth, as well as a weakening of immune functions.
Ministry of Health, Labor and Welfare eJIM Vitamin B6 Supplements / Vitamins / Minerals For the general public "Integrative Medicine" Information Site (ncgg.go.jp)
Natto is one of the leading foods in terms of vitamin B2 content. Natto contains approximately seven times the quantity of vitamin B2 per 100g as compared to boiled soybeans.
In the human body, vitamin B2 is related to energy metabolism, and in addition it protects and preserves the health of skin and mucous membranes. For this reason, it is used in therapeutic medications for angular cheilitis, dermatitis, conjunctivites and so on.
"Information on the Safety and Efficacy of 'Health Foods'" National Institute of Health and Nutrition (nibiohn.go.jp)
