A fermented food containing an extract of at least one plant material selected from the group consisting of turmeric, Houttuynia cordata Thunb., Eucommia ulmoides Oliv., rice bran, persimmon leaves, perilla, clove, cinnamon and Rubus suavissimus S. Lee (Rosaceae) and bacteria of the genus Bifidobacterium. The fermented food contains an excellent and novel material with which the viability of the bacteria of the genus Bifidobacterium can be improved in storage of the product, and even when used in products such as beverages or foods, does not deteriorate the flavor of the product, thereby the bacteria of the genus Bifidobacterium can be contained at high concentration which provides various physiological effects.本發明係以含有1種或2種以上選自薑黃、魚腥草、杜仲、米糠、柿葉、紫蘇、丁香、肉桂及甜茶所成群之植物素材之萃取物，與雙叉乳酸桿菌屬細菌為特徵之醱酵食品。此醱酵食品係由含有可提高活的雙叉乳酸桿菌屬細菌之保存存活性，即使使用於飲食品等，亦不影響風味之優異的新穎素材，含有高濃度之可期待各種生理效果之活的雙叉乳酸桿菌屬細菌。
