I wouldn't let him start taking supplements or making major dietary changes until he has finished with all the diagnostic tests. With the exception perhaps of Pomi-T, it is generally better to change diet than to take more synthesised or modified items. Once the results are all in and he knows which treatment he is going for, you could read Jane Plant's book about possible diet links with breast & prostate cancer, or buy Prostate Cancer Research UK's cookbook (available from Amazon) which is similar to Plant's theories but not as extreme. Briefly, men with PCa are advised to reduce red meat & dairy, and increase garlic, onions, tomatoes (cooked, braised, processed), broccoli and soya. Cranberry juice helps reduce bladder irritation if he has radiotherapy or while the catheter is in post-op.