White Bread, Other High Glycemic Foods, Linked To Lung Cancer: Study

Eating foods that have a high glycemic index — such as white bread, rice, oatmeal and bagels — could increase a person's risk of developing lung cancer, according to a new study.

The glycemic index, a common term to diabetics, measures how a food raises blood-sugar levels. Other foods that are considered to have a high glycemic index (GI), according to the American Cancer Society, include corn flakes, macaroni and popcorn.

Lung cancer is the second-most common form of cancer for both men and women, according to the society, and the deadliest cancer for men and women.

Tobacco use is the leading cause of lung cancer, but just what brings on lung cancer for non-smokers has been unclear. This new study suggests dietary habits could be a factor.

The study, published last week by scientists at the MD Anderson Cancer Center, used a survey of 1,905 MD Anderson patients who had recently been diagnosed with lung cancer and 2,413 healthy people.

“We observed a 49 percent increased risk of lung cancer among subjects with the highest daily GI compared to those with the lowest daily GI,” Xifeng Wu, an epidemiology professor at the University of Texas-Houston and senior author of the study, said in an MD Anderson release.

And the results were more pronounced among non-smokers, a finding that has intrigued some in the medical community.

Among people who had never smoked before, those in the highest GI group were more than twice as likely to develop lung cancer than in the lowest group. For smokers, the highest group was 31 percent more likely than the lowest.

Research linking high GI foods to lung cancer is sparse, according to Marjorie McCullough, a nutritional epidemiologist at the American Cancer Society.

But how non-smokers get lung cancer is a critical question, so the study's findings piqued McCullough's interest. Breathing dangerous chemicals such as radon or family genetics can be a factor, but they do not account for every case.

McCullough was skeptical of the study, which only included non-Hispanic whites and did not account for diabetes, hypertension or heart disease in the subjects, and said extensive follow-up research would be needed to determine a direct correlation.

And the design of the study — interviewing subjects who came down with lung cancer only after they've been diagnosed — could affect some of the responses, McCullough said.

"They might remember their diet before diagnosis differently based on the fact that they’ve been diagnosed," McCullough told Patch.

"In many other cases, results from case-controlled studies aren’t replicated when the subject is denied perspective — people are asked about their diet without cancer, and then they follow them for many years, and their diet before diagnosis is compared with people who get lung cancer and people who don’t."

And future researchers would need to include just that —conduct interviews with a large group of people over an extended period of time and compare the diets of people who eventually got lung cancer with those who didn't, especially among non-smokers.

"What was interesting was the association in people who were never-smokers," McCullough said. "We know smoking is a major cause of lung cancer. And there are many people who get lung cancer who are not smokers. So anything we can learn about the potential causes of lung cancer in non-smokers is important."

• Read the full MD Anderson press release on the study.

Image via ElinorD, Wikimedia Commons