Purpose: Diets with a high glycemic load (GL) or glycemic index (GI) may increase cancer risk. Findings from prior studies on the relationship between GL, GI, and lung cancer risk are inconsistent. We investigated this relationship in a large prospective cohort.
Methods: We analyzed data from the Southern Community Cohort Study, a prospective cohort that includes diverse racial groups predominantly low-income adults aged 40-79 in 12 southeastern states of the USA. We estimated dietary GL and GI values using data collected from food frequency questionnaires at baseline. Dietary GL and GI were energy adjusted by residual method and categorized into sex-specific quintiles. Cox proportional hazard regression was used to assess the associations between dietary GL, GI, and lung cancer risk. We further performed stratified analyses by various factors.
Results: Intakes of individual food items or food groups that commonly contribute to GL were similar between blacks and whites in the cohort. After excluding the first two years of follow-up, 947 incident lung cancers were ascertained among 55,068 participants. Neither dietary GL nor GI was significantly associated with incident lung cancer risk in the overall population (GL: Q5 vs. Q1, HR = 0.88, 95% CI 0.72-1.07, ptrend = 0.29; GI: Q5 vs. Q1, HR = 1.06, 95% CI 0.86-1.30, ptrend = 0.71), nor in subgroups of populations (ptrend > 0.05), in multivariable-adjusted analyses.
Conclusion: Dietary GL and GI were not independently associated with incident lung cancer risk in a large understudied population.
Keywords: Blacks; Glycemic index; Glycemic load; Lung cancer risk; Socioeconomic status.