Cancer Cells are Sugar Addicts

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The science is undeniable: preventing and even reversing cancer could be as simple as altering your diet and depriving the cancer of its favorite food - sugar

In 1924, Otto Warburg, Ph.D., a Nobel Prize winning biochemist, proposed the hypothesis that cancer is a metabolic disease, that affects the way cells use food to make energy. Warburg believed that cancer cells exhibit a preference for using sugar to fuel themselves, even when the oxygen needed for normal cellular energy processes is available.1,2,3,4 He wrote:

"Cancer, above all other diseases, has countless secondary causes. But, even for cancer, there is only one prime cause. Summarized in a few words, the prime cause of cancer is the replacement of the respiration of oxygen in normal body cells by a fermentation of sugar."1

Until recently, Warburg's hypothesis had been marginalized by the persistent belief in the oncology world that cancer is a genetic disease. However, in his book, Cancer as a Metabolic Disease: On the Origin, Management, and Prevention of Cancer, Thomas Seyfried, Ph.D., has put Warburg's work back in the medical limelight.5

In his book, Seyfried argues that cancer is not a genetic disorder, but is, indeed, a metabolic disease. He suggests that the focus on genetic causes is why so little progress in curing or even treating cancer has been made. This is evident when we look at the milestones for cancer research. For the last forty years, the oncology research community has been focusing on genetic causes and drug-based treatments, and the results for the patients have been dismal.

What does it mean to say that cancer is a metabolic disease? Metabolic diseases are conditions in which the metabolism, or the making of energy from the food we eat, is dysfunctional or abnormal in some way.

Normal body cells are able to efficiently use the food we eat and the oxygen we inhale to complete normal cellular respiration and make adenosine triphosphate (ATP), our main cellular energy source. Most of this energy-making process happens in the mitochondria, tiny organelles that are the "powerhouses" of the cell. There are two types of primary food-based fuels that our cells can use to produce energy.

The first cellular fuel is glucose, which is also called blood sugar. Glucose mostly comes from carbohydrates in our diet, and is converted into energy in our cells via a process called glycolysis. In normal cells, glycolysis is a source of other molecules that flow into the mitochondria to complete normal cellular respiration.

The second type of cellular fuel, ketone bodies, come from fatty acids. There are various kinds, and they come from fats we eat or from the metabolism of fats that have been stored in our fat cells. This fat metabolism process is called ketogenesis, and the shift in metabolism that favors fats as the primary source of energy is called ketosis.

Ketone bodies, or ketones, are an important part of human metabolism. They act as a backup system when blood glucose levels fall, through either starvation or carbohydrate restriction. Ketones allow normal cells to be metabolically flexible, so to speak. When glucose levels are low, most normal cells will switch to using ketone bodies for fuel. Even the brain and nerve cells, which are highly dependent on glucose, can use some ketone bodies if there are enough of them circulating in the blood. This ability of a normal cell to use ketones when glucose is unavailable is a sign of good cellular health. It indicates the cell's mitochondria are working correctly.

In contrast, cancer cells are unable to utilize ketones when glucose is low. Cancer cells have damaged mitochondria, and they lack metabolic flexibility. Since they can't use ketones, cancer cells must have glucose to stay alive and grow.

In other words, most cancer cells are vulnerable to any metabolic change that denies them blood sugar or a source of sugar for fuel.

What Does the Scientific Evidence Say?

The general direction of cancer research in the last forty years has been overwhelmingly biased toward genetic factors, and little progress has been made toward a cure or even effective care. Thomas Seyfried has shown in his studies that cancer can be treated with metabolic dietary therapy with good results.

The types of cancers that are most vulnerable to a restricted ketogenic diet are generally those which are more visible on a FDG-PET scan. FDG stands for 18F-fluorodeoxyglucose, which is a drug used to detect cancers. The drug is a metabolically neutral glucose analog (it can't be broken down like normal glucose) to which a radioactive isotope has been added. Since cancer cells have an affinity for glucose, the glucose analog in the injected drug accumulates in the tumor and the radioactive signal can then be easily seen on a PET (positron emission tomography) scan. The more sugar the particular type of cancer uses, the more likely that a restricted ketogenic diet will put metabolic pressure on it and slow or stop its growth.

This has been proven in several studies. In 1995, Linda Nebeling, Ph.D., and her research team put two young girls with brain cancer on a ketogenic diet with the idea that reducing glucose availability should slow the growth of the cancer. The results were very positive. There was a 21.8 percent decrease in glucose uptake at the tumor sites in both girls, indicating that tumor growth was slowing.6

Recently, Eugene Fine, M.D., completed a trial study using a ketogenic diet to treat ten people with advanced, so-called incurable cancer. His results were also promising. At least five of the patients were able to achieve very high ketone levels, which resulted in disease stabilization or remission. Patients also reported that when their ketones were elevated, the side effects of standard radiation therapy and chemotherapy weren't as debilitating.7

Several studies have shown that ketone bodies help diminish the side effects and increase the efficacy of more mainstream cancer treatments such as radiation and chemotherapy. In short, the presence of high levels of ketones make cancer cells more vulnerable to the standard cancer treatments. And there is compelling evidence that ketone bodies are protective of normal cells because they help reduce the inflammation caused by mitochondrial oxidative stress.8,9

Thomas Seyfried's team has shown in several studies that calorie restriction in conjunction with a restricted ketogenic diet improves cancer outcomes because the diet can reduce tumor blood vessel growth; promote cancer cell suicide factors (apoptosis), destabilize the tumor DNA, reduce tumor size, reduce cancer-growth-stimulating IGF-1 hormone, and reduce inflammation.10-14

That's a good track record for a dietary treatment. And a big, big plus for the patient because the diet is inexpensive, as cancer treatments go, and there are no toxic side effects associated with the diet as there are with mainstream treatments.

Treatment Goals of a Restricted Ketogenic Diet

The first and most important fact to know about using a restricted ketogenic diet is that it is very powerful, metabolically speaking. It is advisable, before implementing the diet, to make arrangements to have a health care professional who is knowledgeable about ketogenic diets monitor patient progress.

The successful implementation of a restricted ketogenic diet has three goals:

The primary goal is to reduce circulating blood sugar and insulin levels and, at the same time, increase ketone levels significantly. When blood sugar levels fall low enough and blood ketones are high, cancer cell metabolism and growth can be slowed or stopped. The purpose of higher levels of circulating ketones is to make it possible for the patient to tolerate the very low blood sugar levels that will starve the cancer. Normally, when blood sugar is very low, the brain triggers a hormonal cascade to tell the liver to break down glycogen, a form of stored glucose, to increase blood sugar. This results in the uncomfortable symptoms of low blood sugar, or hypoglycemia. But when ketones are available at high levels in the blood, the brain switches over to using ketones for about half of the fuel it needs, which reduces the likelihood of a hypoglycemic warning. This is metabolic flexibility in action.

The second goal is to use caloric restriction and targeted fasting to minimize any "after meal" blood sugar and insulin spikes that can fuel the cancer. Caloric restriction and intermittent fasting help reduce baseline glucose and insulin levels, and boost ketone production. The ketogenic diet is an excellent tool for this purpose because high-fat foods are very satiating, and elevated ketone levels have the metabolic effect of reducing hunger.

The third goal is to provide treatment for any side effects associated with the diet. This could include introduction of medications to support dietary goals, or changes to medications as the diet progresses. This is another reason why a doctor or a qualified nutritionist or dietitian should be involved to monitor progress when the diet is implemented.

Given the successful use of a restricted ketogenic diet to treat cancer in controlled studies, one would think that mainstream medicine would at least be curious about metabolic dietary therapy. But, so far, little has been disseminated in the media, and many of the big cancer organizations have not embraced the idea.

Last December, The 700 Club, a news program on CBN, ran a story on using a ketogenic diet to treat cancer.15 On the day that show aired, my Ketogenic Diet Resource website ( received over 10,000 visitors, and it continued to receive several thousand visitors each day for weeks afterward.

Clearly, people were interested. I began to get emails from people all over the world, wanting to know how to implement a restricted ketogenic diet for cancer treatment. The emails were hopeful, and many people wrote and said they had asked their physician or a local dietitian for help, only to be refused because of either a lack of knowledge or an unwillingness to step outside the "standard of care."

Quite a bit of information about ketogenic eating has been available on my website for some time, and Well Being Journal has published two of my articles on ketogenic diets (November/December 2012, Vol. 21, No. 6, and July/August 2012, Vol. 21, No. 4); however, after several months of trying to cobble together bits and pieces of information to send back to the people who wrote, it became clear to me an ebook was needed so that a more comprehensive guide could be offered.

I contacted Thomas Seyfried, Ph.D., to ask for permission to reference material and studies from his book, and wrote to Dominic D'Agostino, Ph.D., a ketogenic diet expert at the University of South Florida to ask for assistance in writing the book. I'm happy to say the response was overwhelmingly positive from both gentlemen, and after several months of hard work, the book is now available on my website at:

If you have cancer or know someone who does, I invite you to explore the possibility that a change in diet might help in the fight against that cancer. At the very least, it can offer some relief from the side effects of standard treatments. 

To learn more about natural, evidence-based interventions for Cancer, use the Research Dashboard:


1. Warburg O. The Prime Cause and Prevention of Cancer, March 7, 2013.

2. Warburg O. On the origin of cancer cells. Science 1956;123:309–314.

3. Warburg O. The chemical constitution of respiration ferment. Science. 1928;68:437–443.

4. Warburg OH. The classic: The chemical constitution of respiration ferment. Clin Orthop Relat Res. 2010 Nov;468(11):2833-9. Reprint.

5. Seyfried TN. Cancer as Metabolic Disease: On the Origin, Management, and Prevention of Cancer. Wiley: 2012.

6. Nebeling LC, Miraldi F, Shurin SB, Lerner E. Effects of a ketogenic diet on tumor metabolism and nutritional status in pediatric oncology patients: two case reports. J Am Coll Nutr 1995;14:202–208.

7. Fine EJ, Segal-Isaacson CJ, Feinman RD, Herszkopf S, Romano M, Tomuta N, Bontempo A, Sparano JA. A pilot safety and feasibility trial of a reduced carbohydrate diet in patients with advanced cancer. J Clin Oncol 2011, 29 (suppl; abstr e13573).

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9. Stafford P, Abdelwahab M, Kim D, Preul M, Rho J, Scheck A. The ketogenic diet reverses gene expression patterns and reduces reactive oxygen species levels when used as an adjuvant therapy for glioma. Nutr Metab 2010, 7:74.

10. Seyfried TN, Sanderson TM, El-Abbadi MM, McGowan R, Mukherjee P. Role of glucose and ketone bodies in the metabolic control of experimental brain cancer. Br J Cancer. 2003 Oct 6;89(7):1375-82.

11. Seyfried TN, Sanderson TM, El-Abbadi MM, McGowan R, Mukherjee P. Role of glucose and ketone bodies in the metabolic control of experimental brain cancer. Br J Cancer. 2003 Oct 6;89(7):1375-82.

12. Seyfried TN, Mukherjee P. Anti-Angiogenic and Pro-Apoptotic Effects of Dietary Restriction in Experimental Brain Cancer: Role of Glucose and Ketone Bodies. In: Meadows GG, editor. Integration/Interaction of Oncologic Growth. 2nd ed. New York: Kluwer Academic; 2005.

13. Zhou W, Mukherjee P, Kiebish MA, Markis WT, Mantis JG, Seyfried TN. The calorically restricted ketogenic diet, an effective alternative therapy for malignant brain cancer. Nutr Metab (Lond) 2007;4:5.

14. Zuccoli G, Marcello N, Pisanello A, Servadei F, Vaccaro S, Mukherjee P, Seyfried TN. Metabolic management of glioblastoma multiforme using standard therapy together with a restricted ketogenic diet: Case Report. Nutr Metab (Lond). 2010 Apr 22;7:33.

15. CBN Network. Starving-Cancer-Ketogenic-Diet-a-Key-to-Recovery/ May 18, 2013.

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