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Q: The question of sugar and white flour always comes up. Does sugar feed cancer cells? Am I harming myself and encouraging a recurrence if I eat sugar?
Kathy, Ludington, Michigan
A: The notion that sugar feeds cancer is widespread in the public press. To cut to the chase: it's not that simple. There is not a 1:1 ratio or direct link between eating a bite of sugar and the resulting growth of a certain number of cancer cells. "Sugar" is a term often used to represent dozens of important, natural chemical structures that exist in our bodies. However, most of us hear the word sugar and think of the white form of table sugar.
The typical American diet is high in many processed and refined foods, including sugar and white flour. Replacing these foods with healthy forms of carbohydrates, such as fruits and whole grains, is advised for people who have had cancer. However, being fearful of or restricting intake of certain foods that contain natural sugars is not necessary or healthful.
Here's an example: Should cancer survivors avoid eating oranges because they have natural sugar? For comparison's sake, let's consider that one medium orange contains 12 grams of sugar and a small donut contains 10 grams of sugar. The difference is that the orange also contains fiber and phytonutrients, both of which may play a role in fighting cancer, whereas the donut is just 200 empty calories, devoid of any potential nutritional benefit. Eliminating foods that contain sugar, such as fruits, is not wise for cancer survivors as this limits intake of cancer-fighting nutrients that are important for energy and overall health.
In fact, many cancer patients are led to believe they must follow a restricted sugar diet for fear of causing cancer growth in themselves if they do not adhere. This fear and rigidity often promotes a very stressful experience. The stress will actually lead to an increase in blood sugar as well as compromised immunity. These negative health effects are actually the exact opposite of the purported benefit of such a plan.
There may be a connection, however, between a diet high in refined, processed foods combined with a sedentary lifestyle that may lead a person to become overweight and eventually experience insulin resistance. Insulin resistance can cause an increase in blood levels of insulin and related compounds that may act as growth factors. The connection between body weight, insulin levels and cancer survivorship is currently being researched. In the meantime, becoming more physically active, striving to maintain a healthy weight and eating a plant-based diet including substituting refined sugars and white flour with whole grains and other unprocessed carbohydrates can all help to keep insulin levels in check and promote cancer survivorship.
Read more from our nutritionists about sugar and cancer