Lung cancer is the leading cause of cancer death in the US and smoking is by far the largest risk factor – linked to about 90% of these cancers, according to the CDC. Among other lifestyle factors, researchers are looking at how diet may play a role and this week, a new study found an association between glycemic index and lung cancer.
Glycemic index (GI) is a measure of how much a food with carbohydrates increases your blood sugar. Foods like sugary beverages and cereals made with refined grains are examples of foods high in GI. Previous studies have found associations of GI with other cancers, including colorectal and stomach cancers. AICR’s CUP report on endometrial cancer in 2013 found that that a high glycemic load (related to GI) diet increases risk for this cancer.
In this study, researchers matched patients with lung cancer treated at MD Anderson to healthy patients in the Houston area and found that those reporting the highest GI diet had a greater risk for developing lung cancer than those with the lowest GI diet. It was most pronounced in the people who had never smoked.The increase in blood sugar after eating high glycemic foods leads to high insulin levels and that can promote an environment in the body that promotes cancer cell growth.
Some limitations of the study are that patients were asked about their diet after cancer diagnosis and it did not include information on whether they had chronic diseases like diabetes or heart disease.
This is an interesting finding and may provide clues as to one way diet can influence cancer risk. Glycemic index is a useful tool for research, but for individuals it represents only one aspect of your diet. The index is based on eating that food by itself. When you eat a meal or snack, you typically eat foods that contain protein and fat and that blunts the increase in blood sugar. Your best bet for cancer and other chronic disease prevention is to focus on your overall diet, not just on one measure of specific foods.
We know that an overall cancer preventive diet is one with mostly plant foods that includes leafy greens and non-starchy vegetables with few calories per bite, beans and legumes packed with fiber and protein, and nuts and seeds with healthy fats. They happen to be low in glycemic index, but they also contain nutrients and phytochemicals that promote health in many ways in the body.
A great way to move toward a healthy plant-based diet is to sign up for AICR’s free 12-week program, the New American Plate Challenge that just started this week.