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Cancer & Nutrition: Does Sugar Feed Cancer?
Posted: Nov 27, 2015
Cancer & Nutrition: Does Sugar Feed Cancer? image


One question I hear often from cancer patients and survivors is does sugar feed cancer? I believe it’s important to understand the role sugar plays in cancer so you can make the best choices about:

  • if you will include sugar in your diet,
  • what type of sugar you consume, and
  • how much sugar you consume.

Understanding the relationship between sugar and cancer can help you to reduce the fear that can come up when you think about sugar feeding your cancer.

(Understanding the relationship between sugar and cancer and making changes to your diet and lifestyle as a result, are just a couple of the things you can do to start thriving after cancer. Want more?. There are a ton of small changes you can begin to make today to move from surviving to thriving!)

What is the Connection Between Sugar and Cancer?

A German physiologist and medical doctor named Otto Warburg was the recipient of the Nobel Prize in Physiology in 1931 for his discovery of the unique way cancer cells use fuel and generate energy.

In his research, he documented the two common ways a cell can create energy for its needs. One, which takes place in the presence of oxygen, is called Oxidative Phosphorylation. A second, which produces much less ATP (energy) and is predominate when oxygen is limited, is called Anaerobic Glycolysis.

Cancer cells are different though in that they have their own unique energy pathway, which is a hybrid of these two common ways. It is called Aerobic Glycolysis. In other words, despite oxygen being available and the cancer cell having functioning mitochondria, which could use the more efficient system of phosphorylation, the cancer cell prefers to use glycolysis. In microorganisms, this energy pathway is called glucose fermentation.

Why Should a Cancer Thriver Care About This?

Since cancer cells prefer to use glucose (sugar) as its energy source, could this mean that by removing sugar from your diet you could starve a cancer cell? This suggestion is certainly being touted on the Internet and is recommended by many alternative cancer practitioners. However, it is also beginning to be tested through clinical trials in conventional cancer treatment settings as well.

does sugar feed cancerShould I Eliminate Sugar from My Diet?

Like most nutrition questions I answer, I like to look at this situation like a cost-benefit question. Let’s examine the costs and benefits of cutting out sugar from your diet.

What are the Costs to Cutting Sugar Out of My Diet?

If you think of sugar as “added sugar” like cane sugar, beet sugar, honey, molasses, syrup, sweets and candy, then there isn’t really any downside to cutting sugar out of your diet. You will likely lose some body fat, reduce your triglycerides and your dentist will be happy too. But, if you know anything about nutrition, you know that even healthy whole grains, fruits, certain vegetables and legumes are also eventually converted to sugar by digestion. Avoiding these healthy foods could certainly come at a cost.

Healthy carbohydrate foods, although they are eventually converted to sugar, ALSO contain fibre including prebiotics, beneficial phytonutrients, and important vitamins and minerals. These foods have been shown to help support the immune system, reduce chronic inflammation and act on cancer cells directly. Eliminating these healthy foods could certainly be detrimental to a cancer thrivers risk reduction strategy.

What are the Benefits to Cutting Sugar Out of My Diet?

There is preliminary evidence that some cancers (particularly brain cancers) benefit from a very strict reduction of all sugars from the diet (from healthy and unhealthy sources). This is called a ketogenic diet.

Should I Get Rid of ALL Sources of Sugar?

Beginning a ketogenic diet (very low carbohydrate and high fat diet) for the purposes of treating your cancer is a decision that requires thoughtful consideration. I don’t believe there is a clear answer on this question yet. There are several clinical trials underway, which you may want to investigate if you find yourself drawn to the ketogenic diet as a treatment option.

Clinical Trials of Ketogenic Diets
Cancer Type Being Studied www.clinicaltrials.govReference Number



Pancreatic Cancer NCT01419843
Lung Cancer NCT01419587
Metastatic disease of solid tumors NCT0176468
Recurrent glioblastoma NCT00575146
Head and Neck Cancer NCT01975766

Go to to and type in the number in the right column to find out more, or simply search “ketogenic diet and cancer” to see what trials are available.

I would not suggest a ketogenic diet without proper monitoring by your physician and diet planning with your registered dietitian. If you want to know how a ketogenic diet might help you specifically, begin the conversation with your cancer care team.

The Ketogenic Diet is Too Extreme, Are There Other Changes I Could Make?

If you find yourself shying away from the extreme prospect of a ketogenic diet, or its lack of definitive answers, you are not alone. Sticking to these types of diets are a challenge and only due to sheer determination and strength of will are people able to stick to them. Because this diet does not yet have good scientific evidence to support it, it’s difficult for me to recommend it at this time.

However, until the clinical trials finish, are published and we have a better idea of the benefits of a ketogenic diet, there are still changes you can make and actions that can be taken!

Cut way back on the amount of nutrient-poor added sugars in your diet. This includes candy, soda pop and other sources of sugar that don’t provide a nutritional benefit to the diet.

What is the PET Scan? Did You Know it uses Sugar to Find Cancer?

PET stands for positron emission tomography (PET). This is an imaging procedure a medical team will use to find exactly where cancer is in your body. Active cells such as malignant cancer cells will use sugar as an energy source at a more rapid rate than normal cells. Inactive cells such as benign cells and scar tissue will not use sugar at the same rate.

Prior to the scan a patient is injected with Fluorodeoxyglucose (FDG). This is made by combining a special type of sugar with a safe radioactive component to produce what is called a radioactive tracer. Once injected into a vein, the FDG travels throughout the body. Because of their rapid rate of glucose uptake, cancer cells absorb a greater amount of FDG than normal cells. The FDG is then trapped inside the cell. An image is taken of the body and because of its radioactive tracer the FDG appears on the image. The radiologist reading the scan will see the size and location of the cancer.

Does This Mean Sugar Feeds Cancer?

The mechanism of the PET scan is often sighted by proponents of the Sugar Feeds Cancer theory to demonstrate their belief. BUT, the fact is, sugar feeds every cell in the body. However, cancer cells multiply at a much faster rate and therefore, gobble up sugar faster to fuel their growth. This faster uptake of sugar and FDG is what allows radiologists to see cancer on the PET scan.

What Does This Mean For Me as a Cancer Survivor?

One way I can help you as a cancer survivor become a cancer thriver is by helping you reduce your fear. Fear is powerful but it is something you can conquer. If you are afraid of every carbohydrate food—including healthy whole grains, fruits, and legumes—because they convert to sugar, then you are not choosing the best anti-cancer diet, not to mention creating stress hormones because of your fear.

But you can become a cancer thriver by taking action!

Take action to change your diet and lifestyle in a way that will help to reduce your risk of cancer recurrence AND reduce your fear!

To this end, you need to reduce unhealthy sources of sugar in the diet. Cut back on added sugars like table sugar, syrups, soda pop and other sweetened beverages, candies and sweets.

What Stakeholders Say

“Eating sugar does not make cancer cells grow faster.” – Canadian Cancer Society

“Sugar does not directly cause cancer nor do sugary foods preferentially “feed” cancer cells.” – BC Cancer Agency

More on the Sugar and Cancer Connection

PET Scans


Understanding the Warburg effect: the metabolic requirements of cell proliferation. Vander Heiden MG, Cantley LC, Thompson CB. Science. 2009 May 22;324(5930):1029-33
Selectively starving cancer cells through dietary manipulation: methods and clinical implications. Simone BA1, Champ CE, et al. Future Oncol. 2013 Jul;9(7):959-76.

Jean LaMantia is a registered dietician, cancer survivor, and best selling author of The Essential Cancer Treatment Nutrition Guide and Cookbook. She can be found at

The author Lizzy Smith

about the author
Lizzy Smith

Lizzy Smith was diagnosed with myeloma in 2012 at age 44. Within days, she left her job, ended her marriage, moved, and entered treatment. "To the extent I'm able, I want to prove that despite life's biggest challenges, it is possible to survive and come out stronger than ever," she says.

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