The present invention provides a novel lactic acid bacterium having antioxidant and anti-aging functions and a dementia alleviation effect, and more specifically, provides Lactobacillus pentosus var. plantarum C29 KCCM11291P and Lactobacillus curvatus C3 KCCM430009. In addition, the present invention provides an antioxidant and anti-aging pharmaceutical composition and a dietary supplement containing the Lactobacillus pentosus var. plantarum C29 KCCM11291P or Lactobacillus curvatus C3 KCCM430009 of the present invention as an active ingredient, and a composition for preventing or treating dementia and a dietary supplement for preventing or alleviating dementia, containing Lactobacillus pentosus var. plantarum C29 KCCM11291P or Lactobacillus curvatus C3 KCCM430009 as an active ingredient. Additionally, the present invention provides a composition for preventing or treating dementia, containg a fermentation composition, as an active ingredient, fermented by Lactobacullus pentosus var. plantarum C29 KCCM11291P or Lactobacillus curvatus C3 KCCM430009.
