Counseling patients on cancer diets: a review of the literature and recommendations for clinical practice.

BACKGROUND Many cancer patients use cancer diets. MATERIALS AND METHODS We listed 13 cancer diets simulating an internet search for which we systematically reviewed clinical data. In the next step we derived recommendations on counseling patients using a Delphi process. RESULTS We evaluated the following diets: raw vegetables and fruits, alkaline diet, macrobiotics, Gerson's regime, Budwig's and low carbohydrate or ketogenic diet. We did not find clinical evidence supporting any of the diets. Furthermore, case reports and pre-clinical data point to the potential harm of some of these diets. From published recommendations on counseling on complementary and alternative medicine, we were able to derive 14 recommendations for counseling on cancer diets. CONCLUSION Considering the lack of evidence of benefits from cancer diets and potential harm by malnutrition, oncologists should engage more in counseling cancer patients on such diets. Our recommendations could be helpful in this process.