Due to unproven rumors that he had treated famous celebrities and world leaders, his clinic speciliazing in fresh cell therapy became popular.

[2] There is no medical evidence to suggest his fresh cell therapy is useful for any health problem,[3][4][5] and it has not been approved in several countries for safety reasons.

[7] Niehans promoted it as a cure for many diseases and ailments, such as cancer, homosexuality, anemia, diabetes, heart issues, impotence, and sexual disfunction.

[3] Fresh cell therapy is considered an unproven method of cancer treatment and quackery by medical experts.

[8] In the United States and Switzerland, it is not legally available because of safety concerns and lack of proof of its effectiveness.