More Iron Equals Less Colorectal Cancer
By Michael Mooney
Surprised? Some people who are considered to be "experts," like Dr. Joseph Mercola and Dr. Andrew Weil have said, "Don't take iron. It's toxic."
No wonder people are misinformed - they've heard this notion about toxicity talked about as if it is a fact. It is not.
The study below, by AJ Cross, looked at several measures of iron in the body and found that more iron was associated with less colorectal cancer. Iron has an important role in supporting immune function, so much that the first large study of HIV-positive men by Abrams, at the University of California, Berkeley showed that 54 mg of daily iron from food plus supplements was twice as strongly associated with reducing the progression of HIV to an AIDS diagnosis as 36 mg or 18 mg of daily iron intake.
Cross AJ, et al. Iron and colorectal cancer risk in the alpha-tocopherol, beta-carotene cancer prevention study. International Journal of Cancer. 2006 Jun 15;118(12):3147-52.
In vitro and in vivo studies have associated iron with both the initiation and promotional stages of carcinogenesis. We investigated whether iron was associated with colorectal cancer in a nested case-control study within the alpha-tocopherol, beta-carotene cancer prevention study cohort. Exposure was assessed at baseline, using a 276-item food frequency questionnaire and a fasting serum sample. The study included 130 colorectal cancer cases (73 colon cancers and 57 rectal cancers) and 260 controls. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Supplemental iron intake was only reported for 4 cases and 18 controls; therefore, we were unable to obtain meaningful results for this variable. Comparing the highest to the lowest quartiles, there was an inverse association between serum ferritin and colorectal cancer risk (OR = 0.4, 95% CI = 0.2-0.9) and a suggestion of an inverse association between dietary iron and colorectal cancer risk (OR = 0.4, 95% CI = 0.1-1.1). In addition, serum ferritin, serum iron and transferrin saturation were all inversely associated with colon cancer risk specifically (OR = 0.2, 95% CI = 0.1-0.7, p trend = 0.02; OR = 0.2, 95% CI = 0.1-0.9, p trend = 0.05; OR = 0.1, 95% CI = 0.02-0.5, p trend = 0.003, respectively), whereas serum unsaturated iron binding capacity was positively associated with colon cancer risk (OR = 4.7, 95% CI = 1.4-15.1, p trend = 0.009). In summary, we found a significant inverse association between several serum iron indices and colon cancer risk.
Another study said that higher ferritin was associated with less colorectal cancer. Ferritin is a blood test that tells us how much iron we have stored in our bodies.
Karo I, et al. Iron intake, body iron stores and colorectal cancer risk in women: a nested case-control study. International Journal of Cancer. 1999 Mar 1;80(5):693-8.
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.