The idea that a ketogenic diet might have utility in the treatment of cancer is becoming increasing popular. A ketogenic diet, for those unfamiliar, is a diet which is low enough in insulin stimulating macronutrients (I.E. carbohydrates and protein) to lead to he production of “ketone bodies”, specifically 3-hydroxybutyrate, acetoacetate, and acetone.
The idea that a ketogenic diet will benefit cancer derives largely from the observation, first popularized by Otto Warburg (1), that cancer cells largely use glucose for energy perhaps due to their impaired mitochondria. This led some to speculate that avoiding glucose (carbohydrates) would reduce energy available to the cancerous tissue, limiting its growth.
Unfortunately, a common interpretation of this theory among layman is often along the lines of this:
“Cancer can only use glucose for energy so don’t eat carbs and you’ll starve those stupid cancer cells!”
This view ignores or discounts the fact that ketones can often be used for energy by cancer cells, albeit generally at a lower rate than glucose (3). Additionally, ketones can be used for lipid synthesis by these cells, meaning they can use them as building blocks for their replication (3). Additionally, the ketone acetone can be used to make glucose (4), so the idea of starving cancer cells is clearly less black and white then some assume. However, perhaps a ketogenic diet could still limit cancer growth to some extent, so it may yet be helpful.
Perhaps the type of cancer most commonly researched when examining the therapeutic value of a ketogenic diet is brain cancer. The evidence for this will be examined herein.
In 2007 Thomas Seyfred, perhaps the most prominent researcher of the role of a ketogenic diet on brain cancer, published a study which is often cited as evidence that a ketogenic diet retards brain cancer (5). However, in reality the evidence it provides to this end is highly limited.
While it was found that a calorie restricted ketogenic diet had beneficial effects on two different types of surgically transplanted brain tumors compared to a non-calorie restricted higher carbohydrate control diet, among mice on a non-calorically ketogenic diet had no such beneficial effects were observed.
The unrestricted ketogenic diet (KC-UR), compared to the unrestricted standard diet (SD-UR), produced no benefits in either tumor group on indices of tumor vascularity, survival, or tumor growth:
While the calorie restricted ketogenic diet benefited all these parameters, it can hardly be assumed to be a result of the ketogenic diet itself. Dr. Seyfred’s own research has previously that a restricting the calories from a typical, higher carbohydrate rodent diet benefits brain cancer as much as a calorie restricted ketogenic diet (6,7). Thus, without controlling for variables this study should not be used as evidence that a ketogenic diet benefits brain cancer.
In 2011 a similar study (8) was conducted and again concluded that a ketogenic diet showed no signs of benefiting brain cancer in mice:
In contrast to the previous experiments, one study reported a beneficial effect of a ketogenic diet on brain tumor growth in mice (9). Mice fed the ketogenic diet survived longer andwhen combined with radiation therapy, 9 of the 11 mice on the ketogenic diet seemed cured of their cancer:
Looking over the study, based on the weight gain of the animals, it does appear neither was calorically restricted relative to the other which suggests the effects of the ketogenic diet may have been due to the macronutrient content itself. However, this study used a diet known as Ketocure (registered trademark). Looking up the constituents of the diet suggest to me other elements of this diet could have been beneficial. The following is a list of nutrient information on Ketocure:
Although many elements of this diet are similar to the typical standard diets, this diet used whey as a protein source which some evidence suggests has greater cancer opposing properties than the types of protein sources (like casein and soybeans) commonly used in laboratory rodent diets (10,11). Additionally, this Ketocure diet included several nutrients not typically found in lab rat food, like carnitine and taurine. Preliminary evidence suggests these nutrients may be helpful in treating cancer (12-15). Given all this, one should be hesitant to conclude this diet was exceptional because it of its lack of carbohydrates as opposed to its other unique constituents.
In a better controlled study, researcher Adrienne Scheck and team conducted an experiment comparing the effects of a ketogenic diet with a higher carbohydrate rodent diet on brain cancer in mice (16). Both diets were fairly similar with respect to nutrients. This study reported a beneficial effect of the ketogenic diet on tumor growth and survival:
So while this study suggests a ketogenic diet is beneficial to brain cancer, the application of one study on mice with tumors surgically transplanted into their brain is perhaps limited with respect to humans.
As far as human studies go there have yet to be controlled trials. There have been a few case reports of people with brain cancer eating a ketogenic diet as a dietary adjunct to their treatment. In one of these studies (18) an older woman with glioblastoma multiforme saw an apparent, though temporary remission of her cancer while following a calorie restricted ketone if diet. However, due to the restriction of calories, which evidence suggests often helps limit cancer growth, the apparent positive findings of this study mean little in this context.
The other case report was on two young children being treated for advanced stage astrocytoma brain tumors (17). Both responded with no apparent negative effects, one of these children even seeming to have gone into complete remission. According to the lead researcher this child remains alive more than 15 years later. While this observational is impressive, it’s not unheard of for children with high grade astrocytomes (18). This remission could have been the result of the child’s ketogenic diet or a freak coincidence. That’s the problem with case studies; we can make inferences based on what is expected, but can hardly show strong evidence of cause and effect.
Ketosis, or limiting carbohydrates, is increasingly thought to be a viable way of improving one’s chances of winning the fight against brain cancer. However, with the available evidence I think it’s clear the benefit of ketosis to brain is far from proven. Some interesting data exists which I hope inspire a randomized, controlled clinical trial on this subject, but until such time it seems those using a ketogenic diet to treat brain cancer are entering mostly uncharted waters.
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