SULEN® is a special dietary supplement with lichen extract (Usnea longissima Ach., Usneaceae) which contains sodium usniate. Lichens are unusual combinations of algae and fungi work together as a single organization. They grow on old trees, in cool dampness of the forest and belong to the category of epiphytes, which grow abundantly on trees without taking nutrients from the tree but from surrounding air and moisture of rain or the surface of the host tree. Latest research characterizes sodium usniate as an active ingredient which acts antiinflammatory, antibacterial and astringently. Usnea helps immune system and is especial for throat and respiratory infections. It is an ideal choice for enhancing mouth and throat mucosae of as well as for resistance to colds and flu. It forms a membrane that protects the damaged mucosa. It is not absorbed and acts locally to the mouth and pharynx mucosae. It acts by selective inhibition of infectious agents without damaging the healthy microflora.