You may have heard the hype about the various claimed benefits of the ketogenic diet but is it helpful when it comes to treating cancer in particular? Let’s take a look at what the research says.
The growth of human cells is tightly regulated to ensure that cells only grow and divide in a controlled fashion, and only when necessary. Cancer cells differ from normal cells by the fact that these regulatory mechanisms are affected which leads to rapid and uncontrolled growth of cells. An interesting fact about cancer cells and one which is hallmark to almost all tumours is that these cells rely solely on glucose as a source of fuel. In contrast to normal cells which can adapt to different nutritional conditions by using fat as an energy source when glucose (from carbohydrates) is not available, cancer cells are unable to do so and can only use glucose1.
The aim of using a ketogenic diet to manage cancer is to exploit the metabolic flexibility of normal cells at the expense of the metabolically disadvantaged cancer or tumour cells2. The ketogenic diet (KD) is a high fat, low carbohydrate diet that has been used for decades as an effective therapy for refractory seizures in children2.
Emphasis is placed on such a diet also being calorie-restricted because despite dietary carbohydrate intake being low, the body can still create glucose via a process called gluconeogenesis from protein. In this case cancer cells are also highly efficient at “stealing” glucose cells from the body2. It is therefore important to ensure the ketogenic diet is also calorie-restricted to prevent internal production of glucose which will promote cancer cell growth.
There are a few other potential mechanisms by which ketogenic diets may be beneficial in treating cancer. Firstly a low carbohydrate diet leads to lower levels of the hormones insulin and IGF-1 circulating which may result in fewer divide and grow signals being sent to cancer cells. Secondly, ketone bodies (formed when fat is being used as an energy source) have been shown to inhibit the growth of cancerous cells2.
WHAT DOES THE RESEARCH SAY?
- The first study using the ketogenic diet for human malignant brain cancer was conducted in 19953. The aim was to shift the prime substrate for energy metabolism from glucose to ketone bodies in order to disrupt tumour growth. They studied two girls with non-resectable advanced brain tumours. Within 7 days of beginning the ketogenic diet, blood glucose levels were lower, blood ketones were twenty to thirty folds higher and there was a 21.8% decrease in glucose uptake at the tumour sight. One of the patients showed significant clinical improvements and remained free of disease progression while continuing the ketogenic diet for an additional twelve months.
- In a pilot trial of 16 people with advanced stage cancer, 5 patients completed the 3 month intervention of a ketogenic diet4. These 5 reported improvement in emotional functioning, less insomnia and several other parameters of quality of life remained stable. Temporary constipation and fatigue were the only side-effects found.
- In another pilot study published in 2012, ten subjects with advanced cancer completed 26 to 28 days of the ketogenic diet without associated unsafe adverse effects5. Four of the patients continued to see disease progression; five remained stable or had partial remission. The extent of ketosis, but not calorie deficit or weight loss, correlated with stable disease or partial remission.
There is hope for using a ketogenic diet in cancer prevention and treatment which involves drastically reducing carbohydrate intake and replacing it with healthy fats (particularly Medium-chain triglyceride [MCT] fat such as coconut oil) and moderate amounts of high-quality protein. However this area needs far more research before it can become a first line treatment for cancer or before any recommendation on this topic can be made. It is also far too premature to say that it can be used to treat cancer without the use of other cancer treatments and it is crucial to discuss all the options with an oncologist.