An orally ingestible preparation consisting essentially of Mistletoe lectin I (ML-I), Mistletoe lectin II (ML-II), and Mistletoe lectin III (ML-III), which specifically excludes the nausea-inducing compounds present in mistletoe extracts. The invention also provides for a method of producing said preparation, a method of using said preparation to produce pharmaceutical preparations, and a method for using said preparation in the treatment of patients suffering from cancer and auto immune diseases.