Ketogenic and low-sugar diets for patients with cancer: perceptions and practices of medical oncologists in Canada

Many patients with cancer are interested in complementary therapies, including strategies such as reduced carbohydrate diets. Guidelines regarding the use of these diets during cancer treatment are lacking; therefore, we aimed to explore the perceptions and practices of medical oncologists in Canada regarding low-sugar and ketogenic diets. A cross-sectional, online multiple-choice survey was distributed to 206 Canadian medical oncologists. Questions explored frequency of patient interactions, oncologist perceptions of efficacy, advice given to patients, and concerns about side effects related to reduced carbohydrate diets. Responses were received from 57 medical oncologists in seven of thirteen provinces and territories, with an overall response rate of 28%. Forty-nine percent of respondents were asked at least weekly about a low-sugar diet, and 9% about the ketogenic diet. Eighty-five percent supported the use of a low–added sugar diet in patients with diabetes or hyperglycemia, while conversely 87% did not support the use of a ketogenic diet for any of their patients undergoing active cancer treatment. Respondents felt either that a ketogenic diet was not effective (31%) or that the effect on cancer outcomes was unknown (69%). Ninety-six percent of respondents had concerns about a ketogenic diet for patients receiving active cancer treatment. The role of reduced carbohydrate diets during cancer treatment is topical. Canadian oncologists are particularly reluctant to support a ketogenic diet for patients on active cancer treatment, with concerns about side effects and unknown efficacy. There may be a role for continuing medical education and institutional guidelines to inform these discussions with patients.