Mythbusters: Complementary and Alternative Treatments in Cancer

Victoria Stern, MA


September 02, 2014

In This Article

Sugar-Free Diet

Proposition: Cutting sugar out of one's diet will stop a tumor from growing.

What the science says: After a cancer diagnosis, patients frequently ask their oncologist about the foods they should and shouldn't eat. A particularly common query is whether eliminating sugar will help starve tumor growth.

At a glance, the evidence appears quite compelling. Consuming copious amounts of sugar is associated with a slew of poor health outcomes, including diabetes, obesity, and cardiovascular disease. And studies have consistently shown a link between excess consumption of refined sugars and greater cancer risk as well as a rather robust relationship between being overweight or obese and an increased likelihood of developing cancer.[5,23]

One comprehensive review published in 2011 looked at whether reducing glucose consumption could help prevent or treat cancer.[24] Studies showed that when starved of glucose, tumor cells commit cell suicide in vitro, and that high glucose concentrations may alter gene expression in ways that promote cell growth in tumor cells studied in vitro. Still, there are no RCTs in humans that have evaluated whether sugar fuels cancer growth.

"It is true that when a cell becomes a cancer cell, it changes its cellular metabolism, and in a cell culture dish, a cancer cell prefers sugar," said Dr. Rock. "But in the context of the human body, cancer cells don't behave the same way, so we can't extrapolate from the cell culture to humans."

According to the 2012 ACS guidelines on nutrition and physical activity for cancer prevention, the best diet advice is to consume mostly fruits, vegetables, lean meats, low-fat dairy products, and whole grains and to limit the consumption of red and processed meats and alcohol as well as high-fat, high-calorie foods that may promote weight gain.[5] One study found that adhering to the ACS dietary guidelines was associated with lower mortality from cancer, cardiovascular diseases, and any cause.[25] This prospective study evaluated the effects of dietary patterns on the risk for cardiovascular, cancer, and all-cause mortality among 72,113 healthy women. After following these women for 18 years, the researchers determined that those who consumed a diet high in red and processed meats, refined grains, and desserts had a 16% greater risk of dying from cancer and a 21% greater risk of dying from any cause compared with those who followed a healthful diet of mostly vegetables, fruit, fish, poultry, and whole grains. Although the study did not separate out the effects of different foods on cancer mortality, it contributes to a growing body of literature that demonstrates that maintaining a generally healthy diet can decrease the risk of developing and dying from cancer.

What the experts say: "The sugar in your diet won't promote cancer growth, and there are no studies to date that show that avoiding sugar will shrink a tumor," said Dr. Rock. "Still, no oncologist or nutritionist would recommend a high-sugar diet because patients would be missing out on the beneficial nutrients."

But, Dr. Rock added, "When patients go through chemo- or radiation therapy, their tastes often change and they may lose weight. If putting sugar in food helps some patients get the vitamins and minerals they need, then eating sugar is not such a bad thing. Overall, though, it's best not to consume foods with added sugar or fat."

According to Dr. Deng, eating too much sugar is bad for us -- not just from a cancer standpoint but for many other health reasons. "Although we don't have evidence that eliminating refined sugar will shrink tumor and prolong survival, doing so is a low-risk lifestyle change and will certainly not harm patients. We are not talking about giving people a toxic drug, so there is very little downside." Still, Dr. Deng cautioned, "None of the radical anticancer diets that employ restrictive regimens have been shown to improve survival. The downside to such restrictive diets is that patients run the risk of depriving themselves of essential nutrients."

Verdict: Unconfirmed for a potential anticancer effect of eliminating sugar, but it's important to minimize excess sugar intake as part of maintaining a generally healthy diet.


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