The Codex Alimentarius Regional Standard for Asia is a collection of international food standards and codes of practice. These standards specify the safety requirements for every process in food production, from farm to table, in order to ensure the safety of the food that is distributed throughout the world. To ensure quality, the Codex General Standard also establishes the necessary standards for the ingredients that should be included in food products, including quantities, manufacturing methods, inspection methods and so on.

In the Codex Alimentarius Regional Standard for Asia, natto is classified as a "bacillus fermented soybean product." To distinguish it from other traditional Asian fermented soybean products, it is defined as follows.

"Soybeans (including cracked soybeans; the same hereafter) that are steeped in water or a weak salt solution and then steamed and subsequently fermented with natto bacillus (Bacillus subtilis var. natto.), producing viscous soybeans (with no arbitrary raw materials added following fermentation)."The meaning of "no arbitrary raw materials added following fermentation" means "no salt or other additives added following fermentation for the purpose of flavoring or preservation."

In addition, the unique viscosity of natto (the fine threads that are produced when you lift it with your chopsticks) is also defined: "When the natto soybeans are lifted, visible thread-like elements should be produced.
REGIONAL STANDARD FOR SOYBEAN PRODUCTS FERMENTED WITH BACILLUS SPECIES