High glycemic index diets may raise lung cancer risk, study finds - Video

A surprising new study published in the Annals of Family Medicine reveals an unexpected link between dietary carbohydrates and lung cancer risk, focusing on two key measures: glycemic index (GI) and glycemic load (GL).

The glycemic index (GI) rates how fast a carbohydrate food raises blood sugar on a scale from 0 to 100. Glycemic load (GL) goes a step further by also considering the amount of carbs eaten, showing how much the food actually affects blood sugar.

The study analyzed data from over 101,000 adults enrolled in the U.S. National Cancer Institute’s Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial starting in the 1990s. Participants completed detailed diet questionnaires and were followed for roughly 12 years to monitor lung cancer incidence. Researchers classified participants by their dietary GI and GL, carefully adjusting for smoking and other risk factors to isolate the diet-cancer relationship.

Findings revealed a paradox: people consuming diets with the highest glycemic index had a 13% increased risk of lung cancer compared to those with the lowest GI. This elevated lung cancer risk was observed for both non–small cell and small cell lung cancers. Surprisingly, however, those with the highest glycemic load diets had about a 28% lower risk of lung cancer overall, mainly driven by reduced non–small cell lung cancer risk, with no clear association for small cell types.

These results suggest that not all carbs impact lung cancer risk equally. Diets rich in low-GI, high-quality carbohydrates—such as fruits, vegetables, and whole grains—may help reduce lung cancer risk, while frequent consumption of high-GI foods like refined sugars could elevate it.

While further research is warranted to understand underlying mechanisms, this study encourages thoughtful carbohydrate choices as part of lung cancer prevention strategies, reinforcing a diet emphasizing nutrient-rich, low-GI foods for long-term health.

REFERENCE: Wang, J., et al. (2025) Dietary Glycemic Index, Glycemic Load, and Risk of Lung Cancer: A Population-Based Cohort Study. Annals of Family Medicine. DOI: 10.1370/afm.250132. https://www.annfammed.org/content/23/6/524