To obtain soluble, branched polysaccharides useful for food, drugs, cosmetics, etc., which comprises a main chain having specific repeating side chains, is used for inhibiting binding between β-galactoside lectin and its receptors and has good organoleptic receptivity and texture properties.

The polysaccharide contains a main chain having repeating side chains comprising optionally substituted lactose units only, such as sugars of the formula (wherein Gal is galactose; Glc is glucose; R1 is H or N-acetyl galactosamine; R2 is H, N-acetylneuraminic acid or HSO3; R3 is H or fucose; and n>1), etc. This polysaccharide is obtained, e.g. by fermenting a bacterial strain lactobacillus helveticus CNCM I-1449 using a heat-sterilized, regenerated nonfat milk as a growth medium in a fermented maintaining the pH at 5.5 and separating the polysaccharide through (ultra)centrifugation method, etc.