It is not recommended to follow any restrictive diet if you have been diagnosed with cancer or while undergoing treatment.
Should I follow a Ketogenic diet?
No, neither the National Cancer Control Programme (NCCP) here in Ireland nor any other major cancer organisation recommends the ketogenic diet for cancer patients. It is also not advised for cancer prevention.
What is the theory behind the ketogenic diet in cancer?
All our cells need energy for us to be able to breathe, move and survive. The fuel for energy comes from food. The preferred fuel for most of the body’s cells is glucose (sugar). Sugar is delivered to the cells from carbohydrates.
In the 1920s, a scientist called Warburg found that cancer cells fuel their growth by using large amounts of sugar. He saw cancer cells break down sugar for fuel in a different way than healthy cells. Cancer cells are less effective at making energy from sugar than healthy cells. This is called the Warburg effect (2).
If our body doesn’t have access to sugar, it will start to produce ketones from fat stored in our body. Healthy cells can use ketones for energy but cancer cells may not be able to use them as easily. The theory of the ketogenic diet attempts to deprive cancer cells of sugar.
Is there evidence for using a ketogenic diet in cancer?
Most claims about the benefit of the ketogenic diet and cancer are from studies on cells in test tubes (in-vitro) or animal studies (3). These types of studies are not considered good forms of research. The effects found in animals or cell studies are rarely reproduced in studies of humans (3).
The bottom line is that while good nutrition is important in cancer (and indeed to health in general), the reality is that no diet can cure cancer.
It is not advised to exclude whole food groups, such as carbohydrates from your diet during cancer treatment. Exchanging food groups or multi foods can increase your risk of nutritional deficiencies. It may also affect your ability to maintain weight during cancer treatment. This may have a negative impact on your treatment plan.
We recommend you maintain a stable weight during cancer treatment, even if you are overweight (5). This is because weight loss during cancer treatment can affect your body’s ability to cope with the treatment and the possible side effects (6).
Dr. Aoife Ryan is a Senior Lecturer in Nutrition & Dietetics at University College Cork. For the past 20 years, she has focused her dietetic practice and research in oncology. She is a CORU Registered Dietitian and completed her PhD at the Dept of Surgery, Trinity College Dublin on the topic of nutrition on upper gastrointestinal cancer. She has been awarded INDI Research Dietitian of the Year (2009) and both the Julie Wallace (2015) and Cuthbertson medals (2019) from the Nutrition Society.
Dr. Aoife Ryan