Find more information with regards to cancer and nutrition here - Roots Issue 1
As we have learned, most cancer cells seem to have a sweet tooth. Cancer cells predominantly use glucose as a fuel to form ATP (the building blocks of energy)—the Warburg effect. Furthermore, by reducing blood glucose levels, levels of insulin, insulin-like growth factor, and vascular endothelial growth factor (VEGF), which help drive certain cancers (colorectal, pancreatic, and breast cancer, among others), fall.
PET (Positron emission tomography) scans are a functional imaging technique that is commonly used to detect cancer cells in the body. Individuals are given a radioactive glucose analogue, and the scanner detects areas where this is taken up. Rapidly growing cancer cells utilise this radioactive glucose more readily than other tissue, and thus these areas light up, revealing the tumor(s).
Most experiments studying the effects of the ketogenic diet on tumour growth have occurred in animal studies. I have read through many studies and reviews, and around 60% of preclinical studies show antitumor effects of the keto diet, but around 10% report adverse or pro-cancer effects. Yep, you read that right. This is because certain cancers are sneaky little things that are able to use all sorts of macronutrients other than pure sugar to fuel their growth.
First, let’s go through the “good”. The use of ketogenic diets in these studies has been shown to positively affect (slow or reduce) the growth of cancers in mice with neuroblastomas, adenocarcinomas of the colon, gliomas, astrocytomas, prostate cancer, gastric cancer, non-small cell lung cancer, and metastases (along with hyperbaric oxygen therapy).
However, the ketogenic diet may not be the silver bullet we all hoped for. Ketone bodies, breakdown products of fatty acids, and the predominant fuel source for those on the ketogenic diet, may fuel tumour growth in certain cancers. One study even went as far as stating that ketone-inhibitors should be designed as novel therapeutics to effectively treat advanced cancer patients with tumour recurrence and metastatic disease.
A 2017 study noted that a genetic mutation called BRAFV600E in mice with melanoma was positively associated with tumour growth on a ketogenic diet.
A 2018 study showed that using PI3K-inhibiting drugs with the ketogenetic diet slowed tumour growth in mice, but the ketogenic diet alone accelerated the progression of acute myeloid leukaemia.
Mice bearing renal cell carcinoma xenografts and with signs of Stauffer’s syndrome (a syndrome associated with kidney cancer) experienced dramatic weight loss and liver dysfunction when treated with a ketogenic diet.
A study investigating the effect of long-term ketogenic diet treatment on kidney cancer described a pro-tumour effect of the ketogenic diet in a rat model of tuberous sclerosis complex.
Clinical human trials are severely lacking; most are case studies or pilot reports. Of the studies that exist, most show a reduction in body weight, and some show improved lipid markers. The ketogenic diet reduced total fat mass but was sufficient to preserve lean mass. Interestingly, in those who were cachectic (underweight), the ketogenic diet has shown to increase weight.
Most people on a ketogenic diet tolerate it; however, common side effects include fatigue, constipation, diarrhoea, electrolyte disturbances, and vomiting.
Potential long-term side effects include: kidney stones, gout, and symptomatic hypoglycemia
Those with cancer who a keto diet may be contraindicated, include those who have: tuberous sclerosis complex, tumours containing the BRAFV600E mutation like melenomas, Stauffer’s syndrome, genetic disorders of fatty acid oxidation, carnitine deficiency disorders, and porphyria.
In conclusion and In theory, the ketogenic diet seems like a logical treatment strategy or adjunct for those with cancer. But it is not a silver bullet. Even though the majority of science points towards the benefits of the ketogenic diet and cancer treatment, these studies have been done on mice. Human trials are inadequate, and other trials on mice have also shown the diet causes increased tumour growth. If you still wish to carry on with a ketogenic diet, make sure it is a healthy version of it, and let the medical team looking after you know too.
All in all remember to eat well. Nutritional oncology is not a well-established science yet. The best approach is to be risk-averse and thus aim to reduce consumption of ultra-processed foods and refined sugars. I would stick with nutrient-dense foods that are highly filling. A lower-carb approach may be beneficial for some and may prove to be a useful adjunct to traditional therapies. More studies are needed.