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Does Sugar Really Cause Cancer?


What causes cancer? Genetics? Pollution? Bad luck? A new study published in Cancer Research suggests that you might want to add sugar to that list. (Check out what the new USDA dietary guidelines say about the sweet stuff.)

For the study, researchers at the University of Texas MD Anderson Cancer Center fed infant mice (genetically pre-disposed to breast cancer) either low-sugar, starchy diets or high-sugar ones. Then, researchers looked at them at six months old. Of the mice that had eaten levels of sugar similar to those found in the average American diet, 60 percent had breast cancer. On the other hand, only 30 percent of mice on a low-sugar diet had breast cancer. What's more, breast cancer tumors were larger, grew more quickly, and had more often spread to the lungs in the sugar-loaded mice.

As if belly fat and cavities weren't bad enough, right? The study found that fructose, a simple sugar molecule contained in table sugar and high-fructose corn syrup, increased the body's expression of proteins and fatty acids that contribute to cancer growth.

"The take-home message is that everyone, particularly those who are at a high risk of cancer or already have cancer, should reduce their added sugar intake from processed foods, table sugar, and sugar-sweetened beverages," says Peiying Yang, Ph.D., an assistant professor of palliative, rehabilitation, and integrative medicine at MD Anderson, and co-author of the study.

This isn't the first study to link sugar to cancer. In one 2012 study from the National Cancer Institute, researchers followed 435,674 men and women for more than seven years and found that people who consumed more added sugar had higher rates of esophageal adenocarcinoma, small intestine cancer, and cancer in the lining of the lungs. 

While this new study suggests that sugar, in and of itself, is what causes cancer, sugar's pesky role in weight gain may be an even bigger issue. (Is sugar really a toxic substance?)

"Most oncologists will say that obesity is a risk factor for breast cancer," says Eugene J. Fine, M.D., clinical professor of radiology at the Albert Einstein College of Medicine in New York City. "Chronically increased carbohydrate consumption, which includes sugar, contributes to high blood glucose, high blood insulin levels, and obesity, all factors that have been linked to a variety of cancers, including breast cancer." Indeed, a 2013 review from Italian researchers blamed obesity for 20 percent of all cancer cases.

While Fine recommends cutting carbs—his research shows that when cancer patients do so, they up their chances of remission—he notes that maintaining a healthy weight is more important for cancer prevention than how many grams of sugar you do or don't eat per day. "The bottom line is that if you can find a way that works for you to lose weight and keep it off, then do it," he says.


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