Iron and colorectal cancer: evidence from in vitro and animal studies | Nutrition Reviews

Iron and colorectal cancer: evidence from in vitro and animal studies | Nutrition Reviews

...There is evidence to support the hypothesis that excess iron is associated with increased risk of colorectal cancer, implying that both dietary iron and body iron status increase cancer risk.7–9 There are two distinct routes of exposure of colonic tissue to iron: 1) excess dietary iron (exogenous) passing through the gastrointestinal tract, which may have a local colonic effect directly from the lumen, and 2) excess body iron stores and elevated serum iron (endogenous), which may have deleterious effects on target organs and cells. In a normal individual, the amount of iron absorbed is usually no more than 10% of the amount of iron ingested. Consequently, a significant fraction of dietary iron remains unabsorbed in the small intestine and may enter the colon.10 A number of human and animal studies have demonstrated an association between dietary and total body iron stores, with both being risk factors for the development of colorectal cancer.7,11–13 These studies have been reviewed elsewhere in the literature and will not be covered in detail here.13 Collectively, they support the belief that excess iron is associated with an increased risk of colorectal cancer; however, the source of excess iron (i.e., exogenous or endogenous) is still not clear....