Abstract: The invention concerns an orally administered composition, i.e. a medically active agent for alleviation of uremic symptoms and a method for its preparation. The invention is based on the surprising observation that non-protein nitrogen compounds which accumulate in the body of uremic patients herein referred to as (NPN compounds: in the literature often designated as "uremia toxines") may be biodegraded and biosynthetized to harmless metabolites by utilizing selected non-pathogenic soil microorganisms, as a result of the action of these microorganisms in the intestine of the patient. In this way, at least part of the NPN compounds may be non-toxified, i.e., utilized by the organism. It is also observed that the NPN compounds, as such, do not represent any worthless "waste products" which necessarily have to be excreted. Instead only an excess of NPN not required and not utilized is excreted under normal circumstances.