[1][2] He claimed "Nieper Therapy" could treat cancer, multiple sclerosis, and other serious diseases.

During his career, Nieper was director of the Department of Medicine at Silbersee Hospital in Hanover and for the German Society for Medical Tumour Treatment.

Nieper was also a president of the German Society of Oncology, which promoted alternative medicine.

[4] Nieper experimented with lithium orotate and patented, along with Franz Kohler, calcium 2-aminoethylphosphate (calcium AEP), which he believed could treat such diseases as juvenile diabetes, gastritis, ulcer, thyroiditis, myocarditis and Hodgkin's disease.

[8][9] With associates Dean Burk and Ernst T. Krebs, Nieper opposed fluoridation.