Heme iron from meat and risk of colorectal cancer: a meta-analysis and a review of the mechanisms involved

Red meat and processed meat intake is associated with a risk of colorectal cancer, a major cause of death in affluent countries. Epidemiological and experimental evidence supports the hypothesis that heme iron present in meat promotes colorectal cancer. This meta-analysis of prospective cohort studies of colon cancer reporting heme intake included 566,607 individuals and 4,734 cases of colon cancer. The summary relative risk of colon cancer was 1.18 [95%C.I.: 1.06-1.32] for subjects in the highest category of heme iron intake compared with those in the lowest category. Epidemiological data thus show a suggestive association between dietary heme and risk of colon cancer. The analysis of experimental studies in rats with chemically-induced colon cancer showed that dietary hemoglobin and red meat consistently promote aberrant crypt foci, a putative pre-cancer lesion. The mechanism is not known, but heme iron has a catalytic effect on (i) the endogenous formation of carcinogenic N-nitroso compounds and (ii) the formation of cytotoxic and genotoxic aldehydes by lipoperoxidation. A review of evidence supporting these hypotheses suggests that both pathways are involved in heme iron toxicit

Prediagnostic intake of dairy products and dietary calcium and colorectal cancer survival - results from the EPIC cohort study.

Background We investigated whether prediagnostic reported intake of dairy products and dietary calcium are associated with colorectal cancer (CRC) survival. Methods Data from 3,859 subjects with CRC (42.1% male, mean age at diagnosis 64.2 ± 8.1 years) in the European Investigation into Cancer and Nutrition (EPIC) cohort were analyzed. Intake of dairy products and dietary calcium was assessed at baseline (1992-2000) using validated, country-specific dietary questionnaires. Multivariable Cox regression models were used to calculate hazard ratios (HR) and corresponding 95% confidence intervals (95%-CI) for CRC specific death (n=1,028) and all-cause death (n=1,525) for different quartiles of intake. Results The consumption of total dairy products was not statistically significantly associated with risk of CRC-specific death (adjusted HR Q4 vs. Q1: 1.17 95%-CI 0.97-1.43) nor of all-cause death (Q4 vs. Q1: 1.16 95%-CI 0.98-1.36). Multivariable adjusted HRs for CRC-specific death (Q4 vs. Q1) were 1.21 (95%-CI 0.99-1.48) for milk, 1.09 (95%-CI 0.88-1.34) for yoghurt and 0.93 (95%-CI 0.76-1.14) for cheese. The intake of dietary calcium was not associated with the risk of CRC-specific (adjusted HR Q4 vs. Q1: 1.01 95%-CI 0.81-1.26) nor of all-cause death (Q4 vs. Q1: 1.01 95%-CI 0.84-1.21). Conclusions The prediagnostic reported intake of dairy products and dietary calcium are not associated with disease-specific or all-cause risk of death in patients diagnosed with CRC. Impact The impact of diet on cancer survival is largely unknown. This study shows that despite it's inverse association with CRC risk, the prediagnostic intake of dairy and dietary calcium do not affect CRC survival

Subtypes of fruit and vegetables, variety in consumption and risk of colon and rectal cancer in the European Prospective Investigation into Cancer and Nutrition

Previously, a lower risk of colorectal cancer was observed with fruit and vegetable consumption in the European Prospective Investigation into Cancer and Nutrition within a follow-up period of 9 years which was not fully supported by a recent meta-analysis. Therefore, we were interested in the relation with extended follow-up, also focusing on single subtypes and a variety of intake of fruit and vegetables. Fruit and vegetable consumption was assessed at baseline. After an average of 13 years of follow-up, 3,370 participants were diagnosed with colon or rectal cancer. Diet diversity scores were constructed to quantify variety in fruit and vegetable consumption. A lower risk of colon cancer was observed with higher self-reported consumption of fruit and vegetable combined (HR Q4 vs. Q1 0.87, 95% CI 0.75-1.01, p for trend 0.02), but no consistent association was observed for separate consumption of fruits and vegetables. No associations with risk of rectal cancer were observed. The few observed associations for some fruit and vegetable subtypes with colon cancer risk may have been due to chance. Variety in consumption of fruits and vegetables was not associated with a lower risk of colon or rectal cancer. Although a lower risk of colon cancer is suggested with high consumption of fruit and vegetables, this study does not support a clear inverse association between fruit and vegetable consumption and colon or rectal cancer beyond a follow-up of more than 10 years. Attenuation of the risk estimates from dietary changes over time cannot be excluded, but appears unlikely. What's new? Eating a healthy diet loaded with fruits and vegetables will help you stave off cancer - that's the conventional wisdom. But the relationship between diet and cancer is complex. This study probed the effects of fruits and vegetables on colorectal cancer risk. The authors combed through data from the European Prospective Investigation into Cancer and Nutrition (EPIC) and analyzed total fruit and vegetable consumption as well as individual subtypes. Contrary to earlier results, they found no correlation between fruit and vegetable intake and colorectal cancer risk over a period of more than ten years

Meat and fish consumption and the risk of renal cell carcinoma in the European prospective investigation into cancer and nutrition

Renal cell cancer (RCC) incidence varies worldwide with a higher incidence in developed countries and lifestyle is likely to contribute to the development of this disease. We examined whether meat and fish consumption were related to the risk of RCC in the European Prospective Investigation into Cancer and Nutrition (EPIC). The analysis included 493,179 EPIC participants, recruited between 1992 and 2000. Until December 2008, 691 RCC cases have been identified. Meat and fish consumption was assessed at baseline using country-specific dietary assessment instruments; 24-hour recalls were applied in an 8% subsample for calibration purposes. Cox proportional hazards regression was used to calculate multivariable-adjusted hazard ratios (HR) and 95% confidence intervals (CI). Women with a high consumption of red meat (HR=1.36, 95% CI 1.14-1.62; calibrated, per 50 g/day) and processed meat (HR=1.78, 95% CI 1.05-3.03; calibrated, per 50 g/day) had a higher risk of RCC, while no association existed in men. For processed meat, the association with RCC incidence was prominent in premenopausal women and was lacking in postmenopausal women (p interaction=0.02). Neither poultry nor fish consumption were statistically significantly associated with the risk of RCC. The results show a distinct association of red and processed meat consumption with incident RCC in women but not in men. A biological explanation for these findings remains unclear. What's new? Kidney cancer strikes different populations with different frequency, with developed nations seeing more cases. In this paper, the authors investigate whether certain elements of diet might correlate with increased incidence of renal cell carcinoma. Using data from the European Prospective Investigation into Cancer and Nutrition (EPIC), they assessed the amount of meat and fish consumed in populations representing a wide range of dietary habits. They then correlated this data with renal cell carcinoma incidence. They found no effect from eating fish; consuming red and processed meats did increase risk in women, but not in men

Subtypes of fruit and vegetables, variety in consumption and risk of colon and rectal cancer in the European Prospective Investigation into Cancer and Nutrition

Previously, a lower risk of colorectal cancer was observed with fruit and vegetable consumption in the European Prospective Investigation into Cancer and Nutrition within a follow-up period of 9 years which was not fully supported by a recent meta-analysis. Therefore, we were interested in the relation with extended follow-up, also focusing on single subtypes and a variety of intake of fruit and vegetables. Fruit and vegetable consumption was assessed at baseline. After an average of 13 years of follow-up, 3,370 participants were diagnosed with colon or rectal cancer. Diet diversity scores were constructed to quantify variety in fruit and vegetable consumption. A lower risk of colon cancer was observed with higher self-reported consumption of fruit and vegetable combined (HR Q4 vs. Q1 0.87, 95% CI 0.75-1.01, p for trend 0.02), but no consistent association was observed for separate consumption of fruits and vegetables. No associations with risk of rectal cancer were observed. The few observed associations for some fruit and vegetable subtypes with colon cancer risk may have been due to chance. Variety in consumption of fruits and vegetables was not associated with a lower risk of colon or rectal cancer. Although a lower risk of colon cancer is suggested with high consumption of fruit and vegetables, this study does not support a clear inverse association between fruit and vegetable consumption and colon or rectal cancer beyond a follow-up of more than 10 years. Attenuation of the risk estimates from dietary changes over time cannot be excluded, but appears unlikely

A Prospective Diet-Wide Association Study for Risk of Colorectal Cancer in EPIC

Background & Aims - Evidence regarding the association of dietary exposures with colorectal cancer (CRC) risk is not consistent with a few exceptions. Therefore, we conducted a diet-wide association study (DWAS) in the European Prospective Investigation into Cancer and Nutrition (EPIC) to evaluate the associations between several dietary exposures with CRC risk. Methods - The association of 92 food and nutrient intakes with CRC risk was assessed in 386,792 participants, 5069 of whom developed incident CRC. Correction for multiple comparisons was performed using the false discovery rate, and emerging associations were examined in the Netherlands Cohort Study (NLCS). Multiplicative gene-nutrient interactions were also tested in EPIC based on known CRC-associated loci. Results - In EPIC, alcohol, liquor/spirits, wine, beer/cider, soft drinks, and pork were positively associated with CRC, whereas milk, cheese, calcium, phosphorus, magnesium, potassium, riboflavin, vitamin B6, beta carotene, fruit, fiber, nonwhite bread, banana, and total protein intakes were inversely associated. Of these 20 associations, 13 were replicated in the NLCS, for which a meta-analysis was performed, namely alcohol (summary hazard ratio [HR] per 1-SD increment in intake: 1.07; 95% confidence interval [CI], 1.04–1.09), liquor/spirits (HR per 1-SD increment in intake, 1.04; 95% CI, 1.02–1.06), wine (HR per 1-SD increment in intake, 1.04; 95% CI, 1.02–1.07), beer/cider (HR per 1-SD increment in intake, 1.06; 95% CI, 1.04–1.08), milk (HR per 1-SD increment in intake, 0.95; 95% CI, 0.93–0.98), cheese (HR per 1-SD increment in intake, 0.96; 95% CI, 0.94–0.99), calcium (HR per 1-SD increment in intake, 0.93; 95% CI, 0.90–0.95), phosphorus (HR per 1-SD increment in intake, 0.92; 95% CI, 0.90–0.95), magnesium (HR per 1-SD increment in intake, 0.95; 95% CI, 0.92–0.98), potassium (HR per 1-SD increment in intake, 0.96; 95% CI, 0.94–0.99), riboflavin (HR per 1-SD increment in intake, 0.94; 95% CI, 0.92–0.97), beta carotene (HR per 1-SD increment in intake, 0.96; 95% CI, 0.93–0.98), and total protein (HR per 1-SD increment in intake, 0.94; 95% CI, 0.92–0.97). None of the gene-nutrient interactions were significant after adjustment for multiple comparisons. Conclusions - Our findings confirm a positive association for alcohol and an inverse association for dairy products and calcium with CRC risk, and also suggest a lower risk at higher dietary intakes of phosphorus, magnesium, potassium, riboflavin, beta carotene, and total protein