American College of Nutrition Certified Nutrition Specialist | Author | Professor of Nutrition


Cancer and Sugar

Wonder what cancer cells eat? Glucose, or sugar. And pretty much only glucose. Cancer cells have lost most of the functionality of the normal cells they came from, including the ability to burn fat as fuel.

Most cancer cells lack mitochondria, which is the part of the cell that takes fat and breaks it down into usable fuel (Remember the Kreb’s Cycle from chemistry class?). They can only use glucose, which gives much less energy per molecule.  So they need a lot of glucose to keep dividing and wreaking havoc. Kind of like teenagers. And they get hungry just as fast.

So, how do we get the fuel we need and starve cancer cells at the same time? We can’t avoid all carbohydrates – our brain and blood cells use glucose for fuel too.  We don’t want to starve our blood and nerve cells – it makes them really cranky. There is a solution, and here’s how it works:

Cancer cells have glucose transport (GLUT) channels in their cell membranes, like most cells. Theirs are very sensitive to insulin, which means that to become active they first need to be stimulated by insulin entering the cell. In fact, cancer GLUTs are more insulin-sensitive than in other tissues, and have a lot of GLUTs just waiting for the signal. In contrast, our cells that only use glucose for fuel, like red blood cells and our brain tissue, have GLUTs that do not rely on insulin to become active. They take in glucose in a regular stream, to maintain healthy function and keep us alive.

Insulin stimulating glucose receptors inside a cell.

Muscle and fat, the main storage sites for glucose, have GLUTs that are sensitive to insulin so they can take up extra glucose and store it for future use. When our blood sugar is high, it gets channeled into these cells to keep our blood glucose level healthy and not waste energy. Brilliant, isn’t it? And we can use this to our advantage.

By keeping our blood sugar levels at the lower end of normal, we can literally starve any cancer cells in our bodies. By eating in a way that releases glucose into our bloodstream slowly, only a little insulin is released, and cancer cells only get a little of the glucose. Glucose only provides a little bit of energy per molecule, and gets used up fast. So the cancer cell is left with GLUTs that need insulin to work and very little insulin in your bloodstream. Which all means less fuel for cancer cells to use to divide and grow.

How do you keep blood sugar at the low end of normal? See this blood sugar post for a good start. Eating whole foods, plenty of vegetables, legumes, nuts, fruits and whole grains. It is very important to not avoid all carbohydrates – hypoglycemia (too-low blood sugar) doesn’t help anyone. Our brain tissue, nerve cells, and blood cells need glucose to function properly. Just avoid the white flour and sugar: white bread, cookies, cakes, crackers, pretzels, candy, chips, french fries, you know – the junk. Does is surprise you that cancer cells thrive on junk food? I am guessing not so much.

On an interesting side note, cancer researchers are studying the use of insulin to make chemotherapy more successful. The theory is to link chemo to glucose, flood the body with insulin, and get more of the chemo into the cancer cells. Yes, some will go into the muscle and fat tissue, but since they are not quickly dividing cells they will be less damaged. A good portion of this research is being done at MD Anderson in Houston.

Please remember that fighting cancer with nutrition is most effective when it is done along with your medical treatment. Eating well in incredibly important but is no substitute for the treatment recommended by your physician.

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