Background: The International Agency for Research on Cancer classified processed meats (PMs) as "carcinogenic" and red meat as "probably carcinogenic" for humans. The possible relationship between colorectal cancer (CRC) risk and the mechanisms involved in the carcinogenesis of PMs have not been established yet. Nitrosyl-heme and heme iron have been proposed as potential-related compounds. The aim of this study was to determine the association between nitrosyl-heme and heme iron intake and CRC risk among participants from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Spain study.
Methods: This prospective study included 38,262 men and women from the EPIC-Spain study. Food consumption was assessed using diet history and composition tables, with heme iron and nitrosyl-heme intake calculated from estimated PM item intakes and laboratory analyses. HR estimates were obtained by proportional hazard models, stratified by age at recruitment and study centre and adjusted for sex, total energy intake, education, smoking, body mass index, waist size, physical activity, lifetime alcohol, fibre, calcium and familiar CRC history.
Results: During a mean follow-up of 16.7years, 577 participants were diagnosed with CRC. We found no overall association between nitrosyl-heme (HRT3vsT1: 0.98 (95%IC: 0.79-1.21)) or heme iron intakes (HRT3vsT1: 0.88 (95%IC: 0.70-1.10)) with CRC risk, nor according to tumour subtypes.
Conclusions: Our study found no evidence supporting a link between nitrosyl-heme or heme iron intake and CRC risk in Spanish subjects.
Impact: As research on nitrosyl-heme is preliminary, more heterogeneous studies are necessary to provide more convincing evidence on their role in CRC carcinogenesis.