Have you ever wondered about the unfortunate people who get lung cancer but never smoked a day in their life? Scientists may be closer to an explanation for that seeming conundrum—and it has to do with white bread.
Researchers at MD Anderson Cancer Center at the University of Texas say that if you eat a diet that ranks high on the glycemic index—in other words, a diet full of refined sugars and white flour—you have an increased risk of developing lung cancer. The study, published this week in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research, found that even if you are a non-smoker, a diet high in bagels, breakfast cereal, and birthday cake might indeed be your demise—thanks to lung cancer, of all things.
Lung cancer is the second most common cancer in both men and women in the United States. It's also the most deadly, causing "by far" the most cancer deaths, according to the researchers. Over 150,000 people are expected to die of the disease in the US in 2016, says the American Cancer Society. And even though smoking is the most common cause of lung cancer, plenty of people die from it having never smoked at all.
The researchers got to thinking about the relationship between the glycemic index—which tells you how quickly your blood sugar levels go up after you eat a particular food—and lung cancer because previous research suggested a link between increased levels of insulin-like growth factors and increased lung cancer risk. Stephanie Melkonian, a postdoctoral fellow at MD Anderson and lead author of the study, explains that "Diets high in glycemic index result in higher levels of blood glucose and insulin, which promote perturbations in the insulin-like growth factors (IGFs)."
The study looked at the diet of almost 2,000 patients recently diagnosed with lung cancer, along with 2,413 healthy individuals. Participants self-reported what they ate and the researchers calculated where their eating fell in terms of the glycemic index. Foods high on the glycemic index include corn flakes, popcorn, pretzels, croissants, white rice, white pasta, and white potatoes.
Bottom line: "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," said Xifeng Wu, professor of epidemiology at MD Anderson and a senior author of the study. For those who never smoked, the risk of lung cancer was double for those in the highest GI group. Among smokers, the risk of a high-GI diet elevated the risk 31 percent.
The authors say the lesson of the study is this: limit your intake of foods high on the glycemic index. Instead, choose foods with a low GI, like whole-wheat or pumpernickel bread, rolled or steel-cut oatmeal, and pasta. (And, of course, vegetables and lean proteins.)
You might just want to cut down on the late-night fluffernutters if you want to keep your lungs intact.