Compositions, optionally heat-activated, methods and kits for protecting keratinous fibers from extrinsic damage or repairing keratinous fibers damaged by extrinsic conditions by applying to keratinous fibers a composition comprising at least one compound comprising at least one C.sub.5 to C.sub.7 saccharide unit substituted with at least one amino group and derivatives thereof, and heating the keratinous fibers.