An improvedfilamentous fungi is disclosed that hasan enhanced nutritional profile by utilizingpulsed ultraviolet irradiation. Accordingto the invention, the vitamin Dcomponent of mushrooms and otherfilamentous fungi may be drasticallyincreased with no deleterious affects onappearance with the use of pulsed UVradiation. Mushrooms so treated had upto 1800% DV in one serving of freshmushrooms.