Dietary Iron Source and Lung Cancer Risk: A Case-Control Study in Uruguayan Men

Iron metabolism was found to be implicated in several cancers. Few epidemiologic studies; focusing on iron intake and lung cancer (LC), reported positive associations between heme iron and red meat. Based on estimates of iron contents in representative foods, we conducted the present study with the aim of analyzing dietary iron and its role on the incidence of LC in Uruguayan men, since this population has the highest meat intake worldwide.
A case-control study was performed on 843 LC cases and 1466 controls; using a specific multi-topic questionnaire including a food frequency questionnaire. This matched case-control study was designed according to age-frequency, urban/rural residence, and country region. Food-derived nutrients were calculated from available databases. Total dietary iron was calculated according to its animal, plant, heme and non-heme source after being adjusted by energy. Odds Ratios (ORs) were estimated by logistic regression; being adjusted for potential confounders.
Iron intake was associated with LC risk. Total (OR=3.26), animal (OR=3.73), heme (OR=2.94), and animal non-heme (OR=3.15) iron were positively associated with LC; whereas plant (OR=0.66) and non-heme fraction in total iron (OR=0.56) were inversely associated with LC incidence. Risks were very similar for all histological types of tumors. In addition, stratified analyses showed higher ORs for intense smokers and intense “maté” drinkers.
The source and proportions of dietary iron might be of importance as a link to lung carcinogenesis; suggesting that low intakes of animal sources and high consumption of plant sources could be healthier. Further studies are needed to clarify this point.