A study published on March 7, 2013 in the journal BMC Medicine found that consumption of processed meat is linked to an increase in all-cause mortality. Interestingly, red meat and poultry were not associated with increased risk. The lowest rates of mortality were to individuals who consumed a low to moderate amounts of meat.
The epidemiological study tracked the diets and health of 448,568 Europeans for about a decade. Participants were between the ages of 35 and 69 at recruitment.
Compared to the group with low processed meat consumption, the group with the highest processed meat consumption had a 44% increase in all-cause mortality. Processed meat eaters were also more likely to be current or former smokers and smoking status was associated with increased mortality risk. Non-smokers who consumed the highest amount of processed meat had a lower, but still significant 24% increase in all-cause mortality.
Besides smoking, there were other confounding factors in the study. Individuals that consumed the most processed meat also consumed the fewest fruits and vegetables. As you might expect, those individuals who consumed the highest amount of processed meat and lowest amount of fruits and vegetables had higher rates of all-cause mortality.
Neither red meat nor poultry consumption was significantly associated with cancer, cardiovascular disease, respiratory disease, diseases of the digestive tract, or any other cause of death.
Interestingly, individuals with no processed meat consumption had a higher mortality rate than individuals with low to moderate consumption. Authors point to the benefits of meat consumption as a possible explanation, “Meat is rich in protein, iron, zinc and B-vitamins, as well as vitamin A. The bioavailability of iron and folate from meat is higher than from plant products such as grains and leafy green vegetables.” The authors speculate that nutritional deficiencies from poorly designed vegetarian diets might cause the increased mortality compared to low to moderate processed meat eaters. Furthermore, they consider the possibility that individuals consuming low to moderate amounts of processed meat may be doing in an effort to live a generally healthy lifestyle.
The authors question why processed meat, but not red meat, consumption is associated with increased mortality. One possibility they mention is the higher saturated fat and cholesterol content of processed meats. However, the other foods high in saturated fat and cholesterol, like eggs, have not been linked to increased mortality. Reduction in saturated fat intake has not been shown to significantly reduce all-cause mortality.
Another possibility the authors mention is that processed meats are generally salted, cured or smoked. These processes can increase the amount of carcinogens in the meat. It’s also possible that processed meats are charred to a greater extent than non-processed meats. A recent study showed an association between the “well-doneness” of meat and cancer risk.
As always with epidemiological studies, there is the possibility that the processed meat does not actually cause the increase in mortality, but is simply correlated. While the authors attempted to correct for potential causes of increased mortality in the high processed-meat consumption group, other factors might still confound the study. Nonetheless, the sample size is very large and the results should be taken seriously. Further studies should attempt to identify whether processed meat consumption causes increased mortality. In the mean time, it might be safe to switch out the Slim Jims for steak or chicken.