HOME
Does Eating Red Meat Really Increase Colon Cancer?
On Wednesday, 15 June 2005, the British media were full of the latest food scare. A study of nearly half a million people was clear that eating red meat, they said, dramatically increased the chance of getting colon cancer.
But does it? Here is the abstract of that study and a table from it. See for yourself.
|
Teresa Norat, Sheila Bingham, Pietro Ferrari, et al. Meat, Fish, and Colorectal Cancer Risk: The European
Prospective Investigation into Cancer and Nutrition. J Natl Cancer Inst 2005;97:906-16. ABSTRACT Background: Current evidence suggests that high red meat intake is associated with increased colorectal cancer risk. High fish intake may be associated with a decreased risk, but the existing evidence is less convincing. Methods: We prospectively followed 478 040 men and women from 10 European countries who were free of cancer at enrollment between 1992 and 1998. Information on diet and lifestyle was collected at baseline. After a mean follow-up of 4.8 years, 1329 incident colorectal cancers were documented. We examined the relationship between intakes of red and processed meat, poultry, and fish and colorectal cancer risk using a proportional hazards model adjusted for age, sex, energy (nonfat and fat sources), height, weight, work-related physical activity, smoking status, dietary fiber and folate, and alcohol consumption, stratified by center. A calibration substudy based on 36 994 subjects was used to correct hazard ratios (HRs) and 95% confidence intervals (CIs) for diet measurement errors. All statistical tests were two-sided. Results: Colorectal cancer risk was positively associated with intake of red and processed meat (highest [>160 g/day] versus lowest [<20 g/day] intake, HR = 1.35, 95% CI = 0.96 to 1.88; P trend = .03) and inversely associated with intake of fish (>80 g/day versus <10 g/day, HR = 0.69, 95 % CI = 0.54 to 0.88; P trend <.001), but was not related to poultry intake. Correcting for measurement error strengthened the associations between colorectal cancer and red and processed meat intake (per 100-g increase HR = 1.25, 95% CI =1.09 to 1.41, P trend = .001 and HR = 1.55, 95% CI = 1.19 to 2.02, P trend = .001 before and after calibration, respectively) and for fish (per 100 g increase HR = 0.70, 95% CI = 0.57 to 0.87, P trend <.001 and HR = 0.46, 95% CI = 0.27 to 0.77, P trend = .003; before and after correction, respectively). In this study population, the absolute risk of development of colorectal cancer within 10 years for a study subject aged 50 years was 1.71% for the highest category of red and processed meat intake and 1.28% for the lowest category of intake and was 1.86% for subjects in the lowest category of fish intake and 1.28% for subjects in the highest category of fish intake. Conclusions: Our data confirm that colorectal cancer risk is positively associated with high consumption of red and processed meat and support an inverse association with fish intake. |
COMMENT:
There are a number of points that this study raises which it doesn't answer.
For this analysis, meats were grouped into red meat, processed meat, and poultry. Red meat included all fresh, minced, and frozen beef, veal, pork, and lamb.
Processed meats were mostly pork and beef that were preserved by methods other than freezing, such as salting (with and without nitrites), smoking, marinating,
air drying, or heating (i.e., ham, bacon, sausages, blood sausages, meat cuts, "liver paté", salami, bologna, tinned meat, luncheon meat, corned beef, and others). Lamb and poultry are rarely processed into these types of meats in Europe.
Apart from the processed meats, we have been eating all of these meats for several thousands of years – without any history of colon cancer. Many peoples in the world still do. So why should they be carcinogenic now?
You will notice from the table below that red meat intake does not increase the risk in Aarhus and Potsdam (1.00 means no effect) and it is protective in Italy (0.96 means 4% lower cancer risk in relative terms). In the other countries, there is a slight increase (1.01 means a 1% increase). So in some countries eating red meat seems to be harmful, in another it is beneficial, and in yet more it has no effect one way or the other
You will also notice that the confidence interval figures all cross 1.00, so some of the subjects in all centres used in this trial benefitted from eating red meat even in those countries where it appeared to increase the risk.
So what is going on?
All these countries have different dietary cultures and even people within them eat different foods and combinations of foods. They also will prepare, store and process them in different ways.
As the numbers are all pretty close to 1.00 (which would indicate no effect one way or the other), I suspect that they are merely artifacts which have little if any practical meaning, particularly as lumping fresh meats and processed meats together makes a nonsense of the whole exercise.
And the authors do admit that:
"Our study has several limitations. Most important, methods used in nutritional epidemiology are known to provide imprecise estimates of food intake. Random measurement errors of food intake lead to the attenuation of the disease risk estimates"
So any or all of those could be the answer.
Will I cut down on red meat? No! Although, having said that, I tend not to eat processed foods
And here is one other confounding factor: It has been shown for over a century that lean meat is not as healthy as fat meat. The Italians might have benefitted because they eat a lot more animal fat than do we.
So, the real message might actually be that we should eat fat meat to prevent colon cancer. Just a thought.
| Center |
Number of cases |
Hazard Ratio |
| Aarhus | 56 | 1.00 (0.93-1.07) |
| Copenhagen | 121 | 1.01 (0.97-1.05) |
| France | 174 | 1.02 (0.98-1.05) |
| Heidelberg | 48 | 1.04 (0.99-1.10) |
| Postdam (sic) | 66 | 1.00 (0.95-1.06) |
| Italy | 101 | 0.96 (0.91-1.02) |
| Utrecht | 75 | 1.03 (0.97-1.10) |
| Spain | 110 | 1.02 (0.98-1.06) |
| Malmo | 194 | 1.02 (0.99-1.06) |
| Umea | 78 | 1.01 (0.94-1.08) |
| UK | 172 | 1.03 (1.00-1.07) |
| UK Health conscious | 68 | 1.03 (0.97-1.09) |
| All EPIC | 1389 | 1.02 (0.99-1.06) |
(Table from the study)
Multivariable hazard ratios and 95% confidence intervals from calibrated analyses of colorectal cancer for individual center in the European Prospective Investigation into Cancer and Nutrition (EPIC) Cohort. Hazard ratios (HRs) per 100-g increase in intake and 95% confidence intervals (CIs) were calculated for calibrated intakes of red and processed meat . Hazard ratios were calculated from beta coefficients from Cox regression models adjusted for age, sex, energy from nonfat sources (continuous variable), energy from fat sources (continuous variable), height (tertiles defined for each sex and center), weight (tertiles defined for each sex and center), work-related physical activity (no activity, sedentary, standing, manual, or heavy manual) smoking status (never, former, or current smoker), fiber intake (grams per day) and alcohol consumption (grams of day). Centers with fewer than 50 case patients with colorectal cancer are not included. The hazard ratio figures correspond to the centerspecific hazard ratios (per 100-g increase in intake) and 95% confidence intervals.
Last updated 16 June 2005
Related Articles
