A composition containing Lactobacillus paracasei , a culture or fermentation thereof, or a polysaccharide produced by it as an active ingredient is very effective for preventing or improving type IV allergies, and is particularly useful Foods, medicines, feeds, and cosmetics that act to prevent or improve contact dermatitis.含有屬於副乾酪乳酸桿菌(Lactobacillus paracasei)之乳酸菌菌體、其培養物或發酵物或者其所產生之多醣類作為有效成分之組成物對於預防或改善第IV型過敏甚是有效，尤其可供用作用以預防或改善接觸性皮膚炎之飲食品、醫藥品、飼料及化妝品。
