It’s Not Just Meat: Carbs Can Raise Cancer Risk, Too

But we still don't know how

There's no denying that hamburgers are delicious. But according to a new study, men who ate them often were much more likely to develop prostate cancer. chichacha via Flickr, CC by 2.0

Scientists have long known that foods can raise or lower a person’s risk for developing cancer. But unraveling which foods can lead to which cancers—and for what kinds of patients—has been anything but easy. The most obvious example was the World Health Organization’s recent declaration that eating processed meats can increase a person’s risk of colorectal cancer. Now it seems that some types of carbohydrates and sugars might also increase a person’s cancer risk; people who regularly consumed sugary drinks were three times more likely to develop prostate cancer, and processed carbohydrates like those found in pizza and hamburgers doubled their risk. The researchers presented their work yesterday at this year’s Experimental Biology meeting.

The researchers have tracked the diets of over 3,000 volunteers since 1991. Periodically, they gave participants questionnaires about the types of foods they usually ate, then ranked their foods based on whether the carbohydrates were “good” (legumes, non-starchy vegetables, fruit, whole grains) or “bad” (processed meats, sugary soft drinks, fruit juices). Then they compared the participants’ food sources to their cancer rates, controlling for a number of factors.

They found that people who ate more “bad” carbs were 88 percent more likely to develop prostate cancer. For those who consumed a lot of processed meats and sugary beverages, that risk was even higher. On the other hand, women who ate more “good” carbs were 67 percent less likely to develop breast cancer. In particular, legumes like beans and lentils lowered patients’ overall risk of developing cancer by 32 percent.

“Our study showed very strong associations between certain foods and cancer, in particular with prostate cancer,” Nour Makarem, a doctoral student at New York University and the lead author on the study, said in a press release. “There had not been very many studies on food sources and prostate cancer previously.”

There are some big caveats here, though. Because of the study design, the researchers don’t know the mechanism that connects sugar and cancer development—that would require much more technical studies in the future. They also note that 99 percent of their study participants were Caucasian. That would have almost certainly thrown off their conclusions, especially since black men are much more likely to develop prostate cancer. It’s also difficult to separate patients’ eating habits from their body mass index, which is important because obesity is a known risk factor for a number of types of cancer, though its link to prostate cancer is more tenuous. What’s more, even foods that have been repeatedly shown to increase cancer risk, like processed meats, are not as carcinogenic as other factors like smoking.

At this early stage, it’s impossible to know just what this association means. Nonetheless, it’s a robust one, the researchers say. Future studies will likely look into the mechanism that might make sugars and carbohydrates increase a patient’s cancer risk.