Vitamin
Japanese: ビタミン
Organic compounds that regulate body functions in small amounts. Many increase during fermentation, enhancing the nutritional value of fermented foods.
Vitamins are organic compounds that regulate metabolism and body functions in trace amounts. Since the human body cannot synthesize most of them sufficiently, they must come from food.
What makes fermentation fascinating is that microorganisms 'create' vitamins. Bacillus subtilis var. natto produces vitamin K2; koji mold generates B vitamins like biotin and niacin. Nutrients absent in raw ingredients appear after fermentation.
Part of why miso and natto are considered healthful lies in this microbial vitamin production. Fermentation doesn't just change flavor—it transforms nutritional quality itself.