Iron intake, body iron stores and colorectal cancer risk in women: a nested case-control study.
ABSTRACT Accumulated evidence suggests that increased body iron stores may increase the risk of colorectal cancer, possibly via catalyzing oxidation reactions. We examined the relationship between iron status and colorectal cancer in a case-control study nested within the New York University Women's Health Study cohort. For 105 incident cases of colorectal cancer with an average follow-up of 4.7 years and 523 individually matched controls, baseline levels of serum iron, ferritin, total iron binding capacity (TIBC) and transferrin saturation were determined as indicators of body iron stores, and total iron intake was assessed based on their diet and supplement intake. Overall, there were no associations between the risk of colorectal cancer and any of these indices except for serum ferritin, which showed a significant inverse association. When analyzed by subsite, there was an increasing trend in risk of cancer of the proximal colon with increasing total iron intake (p-value for trend = 0.04). In addition, a significantly increased risk of colorectal cancer associated with higher total iron intake [odds ratio (OR) = 2.50; 95% confidence interval (CI): 1.06-5.87] was observed among subjects with higher intake of total fat. Our results do not support a role of increased body iron stores in the development of colorectal cancer, but suggest that luminal exposure to excessive iron may possibly increase the risk in combination with a high fat diet.
- SourceAvailable from: Geoffrey C Kabat
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- "We did not have information on use of iron supplements, which represent an important contributor to total iron intake in users. In a cohort study of New York City women enrolled from 1985 to 1991 (Kato et al, 1999), 69% of participants reported use of vitamin/mineral supplements, which accounted for 38% of total iron intake. Other surveys carried out in the United States in the 1980s indicate that over 40% of women currently consumed one or more vitamin or mineral supplements, and fewer than half of users reported taking a preparation containing iron (Stewart et al, 1985). "
ABSTRACT: We used data from a large cohort study of Canadian women to assess the association of meat intake and dietary intake of iron and haem iron with risk of endometrial cancer. Among 34,148 women with an intact uterus at baseline and followed for a mean of 16.4 years, we identified 426 incident endometrial cancer cases. Data from a food frequency questionnaire administered at baseline were used to calculate intake of all meats, red meat, total dietary iron, iron from meat, haem iron, and non-haem iron. Analyses were carried out using Cox proportional hazards models with adjustment for known risk factors and covariates. We found no association of intake of meat or any of the dietary iron-related variables with risk of endometrial cancer.British Journal of Cancer 02/2008; 98(1):194-8. DOI:10.1038/sj.bjc.6604110 · 4.82 Impact Factor
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- "However, a number of limitations should also be pointed out. No information was available for iron derived from nutritional supplements, which, in a cohort study from New York (Kato et al, 1999), accounted for 38% of total iron intake. Additionally, zinc intake, which in two studies (Lee et al, 2004; Larsson et al, 2005) was inversely associated with risk of colon cancer, was not estimated from the original dietary database used in this study. "
ABSTRACT: In a cohort study of 49,654 Canadian women, we assessed the association of colorectal cancer with total iron and heme iron intake, excluding iron supplements. Among women aged 40-59 years, followed for an average of 16.4 years, we identified 617 incident colorectal cancer cases. Data from a food frequency questionnaire administered at baseline were used to calculate red meat intake and intake of total dietary iron, iron from meat, and heme iron. Analyses were carried out for all cases and for the proximal colon, distal colon, and rectum, using Cox proportional hazards models. We found no association of intake of iron, heme iron, or iron from meat with risk of colorectal cancer overall or with any of the subsites, nor was there effect modification by alcohol consumption or hormonal replacement therapy.British Journal of Cancer 08/2007; 97(1):118-22. DOI:10.1038/sj.bjc.6603837 · 4.82 Impact Factor
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- "Nelson also uses some US data to demonstrate how the use of iron supplements in women is greater than in men and how total pharmacological iron intake may exceed that from food sources of iron. Other studies reported either no association (Benito et al. 1991; Benito et al. 1993; Bird et al. 1996; Kato et al. 1999; Little et al. 1993) or an inverse association (Hoff et al. 1986; Tseng et al. 1997; Tuyns et al. 1987) between dietary iron intake and risk of CRC or adenoma . Moreover, the reported positive associations may be the result of early disease giving rise to symptoms of iron shortage, resulting in use of iron supplements. "
ABSTRACT: Summary It has been hypothesised that high iron stores increase the risk of diseases such as coronary heart disease and cancer. In summary, in spite of the theoretical possibilities that high exposure to either dietary or systemic iron might increase heart disease or cancer risk, the evidence suggests that this is not the case in healthy individuals. However, some questions remain unanswered including the risk of colon cancer in individuals with high dietary iron intakes (either via a high intake of red meat, fortified foods or frequent supplement use). It is probable that much of the non-haem iron will remain unabsorbed, which potentially may damage the colonic mucosa and increase the risk of large bowel cancer. Furthermore, the risk of cardiovascular disease and cancer in individuals who carry a mutation of HFE, the gene for haemochromatosis, many of whom may be asymptomatic, may be greater than the general population, particulary when dietary iron intake is high. This paper summarises the basis of iron metabolism and examines the theoretical reasons for an association between iron and cardiovascular disease (CVD; includes coronary disease, vascular disease & myocardial infarction) and cancer. It also revisits the studies designed to investigate the role of iron in CVD and cancer.Nutrition Bulletin 08/2002; 27(3):165 - 179. DOI:10.1046/j.1467-3010.2002.00253.x