Thanks to a concerted public awareness campaign over the years, people realize that smoking increases the risk of lung cancer. This cancer is the second most prevalent form in the United States and also the deadliest. However, many are surprised to learn that lifestyle factors -- such as diet – can also play a role in the development of this kind of cancer. For instance, some studies have found that diets high in fruits and vegetables may lower the risk of lung cancer; in comparison, the risk increases when a person eats more red meat, saturated fats and dairy products.
Now a study out of the University of Texas MD Anderson Cancer Center — which is the largest of its kind — links eating a diet rich in high glycemic foods with an increased risk of developing lung cancer. It follows in the wake of other studies on the glycemic index that suggest that diets rich high glycemic index foods may contribute to type 2 diabetes and coronary heart disease.
What is glycemic index?
According to the University of Sydney’s Human Nutrition Unit of the School of Molecular Bioscience (which is the self-proclaimed home of this rating system), the glycemic index (GI) ranks carbohydrates on a scale of 0-100 based on the extent that blood sugar increases after eating the specific food. Foods that have a high GI are rapidly digested and absorbed, leading to large fluctuations in blood sugar levels. In contrast, foods that have low GI ratings are slowly digested and absorbed, thus leading to a gradual increase in both blood sugar and insulin levels.
Examples of foods with a high GI index include white bread, bagels, corn flakes, puffed rice, bran flakes, instant oatmeal, short-grain white rice, rice pasta, macaroni and cheese from a mix, russet potatoes, pumpkins, pretzels, rice cakes, popcorn, saltine crackers, melons, and pineapple. Medium GI foods include whole wheat, quick oats, brown rice, wild or basmati rice, and couscous. Examples of low GI foods are 100-percent stone-ground whole wheat or pumpernickel bread, rolled or steel-cut oatmeal, oat bran, muesli, pasta, converted rice, barley, bulgar, sweet potatoes, yams, lima/butter beans, peas, legumes, lentils, most fruits, non-starchy vegetables, and carrots.
Glyxemic index and lung cancer
For this study, the MD Anderson researchers sent surveys to 1,905 patients who were newly diagnosed with lung cancer and to 2,413 healthy individuals. The survey asked participants to describe their past dietary habits and health histories.
Researchers then took the data and analyzed the foods that participants consumed. Dietary glycemic index as well as glycemic load (a related measure of carbohydrate quantity) were calculated using published GI values of specific foods. Participants were then grouped based on their GI and GL values.
Interestingly, the researchers’ analysis uncovered a 49 percent increased risk of developing lung cancer among subjects whose diet consisted of foods with the highest daily GI index. Furthermore, researchers found that people who had never smoked and who consumed the highest GI diet were more than 50 percent more likely to develop lung cancer than non-smokers who ate a low-GI diet. The analysis also suggested that among smokers, the risk for lung cancer between those eating a high-GI diet and a low-GI diet differed by 31 percent.
Furthermore, a high GI diet also was significantly associated with participants who were diagnosed with squamous cell carcinoma, a type of lung cancer.
This study suggests that attending to daily lifestyle decisions really does matter when considering lung cancer.
“The results from this study suggest that, besides maintaining healthy lifestyles, such as avoiding tobacco, limiting alcohol consumption and being physically active, reducing the consumption of foods and beverages with high glycemic index may serve as a means to lower the risk of lung cancer,” said Xifeng Wu, M.D., Ph.D., an MD Anderson professor of epidemiology and senior author of the study.
Ackerman, T. What’s In Your Lungs? Diet, Not Just Smoking, Can Cause Common Cancer Form. Houston Chronicle. 2015.
American Index and Diabetes. Glycemic Index and Diabetes. 2014.
MD Anderson. Dietary Glycemic Index Linked to Lung Cancer Risk in Select Populations. 2016.
The University of Sydney. About Glycemic Index. 2015.
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