PURPOSE: To prepare a health food having hypoglycemic effect and useful as a food for the patient of hypertension or diabetes, by drying the filter cake of KUROZU or FUROZU (unrefined natural vinegar).

CONSTITUTION: Rice malt, steamed rice, water, etc. are charged into a fermentation vessel, the vessels are placed in the open air, and the content is subjected to fermentation under natural conditions for several months or several years. The saccharification, alcoholic fermentation and acetic acid fermentation take place successively during the fermentation process. The fermentation product is filtered and sterilized to obtain KUROZU or FUROZU. The filter cake obtained as a by-product is freeze-dried in vacuum or dried in the shade at about ≤20°C to obtain the objective health food.