Lung cancer is one of the leading causes of cancer death worldwide, and it is often linked to smoking. However, scientists are learning that smoking is not the only factor that influences risk.
Diet and everyday eating habits may also play a role in how cancer develops over time. A large long-term study has now found that the types of carbohydrates people eat could affect their chances of developing lung cancer.
The research, published in The Annals of Family Medicine, examined more than 100,000 adults who participated in a major U.S. health project known as the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial.
When these participants joined the study in the 1990s, they filled out detailed questionnaires about their diets. Researchers then followed them for about 12 years to see who developed lung cancer.
Scientists focused on two important measures related to carbohydrates: the glycemic index and the glycemic load. The glycemic index measures how quickly a food raises blood sugar levels after eating.
Foods with a high glycemic index, such as white bread, sugary snacks, and refined grains, cause blood sugar to rise rapidly. Foods with a lower glycemic index, such as whole grains, vegetables, and most fruits, lead to slower and steadier increases.
Glycemic load takes into account both how quickly a food raises blood sugar and how much carbohydrate it contains. This measure reflects the overall effect of a person’s diet on blood sugar levels throughout the day.
After tracking participants for many years, researchers found a clear pattern. People whose diets were highest in glycemic index had a higher risk of developing lung cancer compared to those whose diets had the lowest glycemic index.
Overall, the risk was about 13 percent higher. This increased risk was seen for both major types of lung cancer, including non–small cell lung cancer, which is the most common form, and small cell lung cancer, which tends to be more aggressive.
Surprisingly, the results for glycemic load were different. People with diets highest in glycemic load had about a 28 percent lower risk of lung cancer than those with the lowest glycemic load. The protective pattern was strongest for non–small cell lung cancer.
Researchers are still trying to understand why these two measures show different effects, but the findings suggest that the quality of carbohydrates may be more important than the total amount consumed.
High-glycemic foods can cause repeated spikes in blood sugar and insulin, a hormone that helps control glucose levels. Over time, these spikes may lead to inflammation and other changes in the body that could encourage cancer growth.
Diets rich in high-quality carbohydrates, such as vegetables, fruits, and whole grains, provide fiber, vitamins, and protective compounds that support overall health and may help reduce cancer risk.
Importantly, the researchers adjusted their analysis for smoking and other lifestyle factors, which are major influences on lung cancer risk. This means the observed associations were not simply due to differences in smoking habits between participants.
The study suggests that choosing healthier carbohydrate sources could be one way to lower lung cancer risk. Instead of relying heavily on refined grains and sugary foods, people may benefit from eating more plant-based foods that digest slowly and keep blood sugar levels stable.
In reviewing these findings, it is important to remember that the study shows an association rather than direct cause and effect. Diet is only one part of a complex picture that includes genetics, environment, and lifestyle. However, the large number of participants and long follow-up period make the results meaningful and worthy of further research.
Overall, this study adds to growing evidence that everyday food choices can influence long-term health in ways people may not expect. While avoiding smoking remains the most important step in preventing lung cancer, adopting a balanced diet rich in whole foods may also help protect the lungs and reduce risk over time.
If you care about your lungs, please read studies about a review of COPD-friendly foods for lung health, and can Vitamin C and E help fight lung cancer.
For more health information, please see recent studies about how diet influences lung health, and these vegetables could benefit your lung health.
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