Vitamin D supplementation has a beneficial effect on cancerous patients, although it can influence the redox- and metal homeostasis. The aim of our investigation was to demonstrate the effect of vitamin D consumption on the redox- and metal homeostasis in prostate cancer, because of the recommended daily dose increased from 200 IU to 2000 IU in recent years in Hungary. Forty-three volunteers were involved in the study. The grouping was applied according to the clinical routine laboratory parameters (vitamin D) and the tumor markers (PSA, fPFA). Patients were divided into 5 groups: (A) patient control (N = 8), (B) patient control with vitamin D treatment (N = 9), (C) high-risk prostate cancer group (N = 6), (D) high-risk prostate cancer group with vitamin D treatment (N = 8) and (E) vitamin D treated cancerous group with androgen deprivation therapy (N = 11). The element concentrations were determined with ICP-OES. Among the redox parameters, free radical scavenging capacity and H-donating ability were determined with luminometry and spectrometry. Vitamin D treatment caused differences in the metal- and redox homeostasis in either patient control and cancerous groups. The concentration of Fe, Cr, and Pb significantly increased in the erythrocytes of prostate cancer patients. According to the higher scavenging capacity by vitamin D treatment, it seems that vitamin D helps to equilibrate the redox homeostasis that could affect the outcome of cancer positively. However, the tendency in the metal element status does not give a clear explanation of cancer's outcome, but the accumulation of Pb by vitamin D supplementation needs to be taken into more serious consideration in set terms of occupational diseases.